专利摘要:
The present invention relates to a detecting device for detecting NH3 in a gaseous sample, the detecting device comprising a detecting element comprising: a first region comprising a p-type metal / oxide / semiconductor material (MOS) comprising NiO; and a second region comprising n-type MOS material comprising In2O3; the first region being adjacent to and in contact with the second region.
公开号:FR3044769A1
申请号:FR1654458
申请日:2016-05-19
公开日:2017-06-09
发明作者:Prabir K Dutta；Chenhu Sun
申请人:Ohio State Innovation Foundation；
IPC主号:

专利说明:

SENSORS USING SEMICONDUCTOR OXIDE P-N HETEROSTRUCTURE AND METHODS OF USING SAME
BACKGROUND OF THE INVENTION The gaseous ammonia present in the atmosphere at levels of the order of ppb comes mainly from various anthropogenic sources, such as the combustion of fossil fuels, the use of fertilizers and metabolic activities. As exposure to ammonia can have health effects, the detection of ammonia in the environment is necessary. Ammonia is also produced in the human body and the monitoring of ammonia in human exhaled air can be correlated with several physiological conditions for the purpose of diagnosing a disease. The normal physiological range of ammonia in exhaled air is in the region of 50 to 2000 ppb. Each human exhalation contains more than 1,000 trace organic compounds, which makeshaline a highly complex substance. The development of sensors to detect low levels of ammonia in the environment and human haine is a complex problem because the sensitivity required is of the order of ppb and a discrimination compared to other gases present at concentrations much higher. higher must be possible. Summary of the invention
P-n systems and sensors based on metal / oxide / semiconductor heterostructure (MOS) are provided herein. The sensors and systems can be used to detect and / or quantify the ammonia in a gas sample, such as a breath sample, an environmental sample or a flue gas sample. In some cases, the sensors and systems described herein may be used to detect and / or quantify ammonia at concentrations up to 5,000 ppb (for example, at concentrations of 50 ppb to 2,000 ppb , at concentrations of 50 ppb at 1000 ppb, or at concentrations of 50 ppb at 500 ppb). Sensors and systems can be used to detect and / or quantify ammonia in the presence of other gases, such as carbon monoxide and nitric oxide.
In some cases, sensors and systems can be used to detect and / or quantify ammonia in the presence of one or more hydrocarbons, such as an aromatic hydrocarbon (eg, toluene, o-xylene, or combination thereof), an aliphatic hydrocarbon (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), a functional organic compound (e.g., acetone , Acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methyl furan, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof ), or a combination thereof. In some embodiments, the sensors and systems can be used to detect and / or quantify ammonia at concentrations of less than or equal to 5,000 ppb (for example, at concentrations of 50 ppb to 2,000 ppb, at concentrations of 50 ppb at 1000 ppb, or at concentrations of 50 ppb at 500 ppb) in the presence of one or more hydrocarbons (for example, one or more hydrocarbons at a concentration of 50 ppb at 5 ppm), such as or more aromatic hydrocarbons (e.g., toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, isoprene, 3-methyl or a combination thereof), one or more functional organic compounds (e.g., acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methyl furane, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination of e), or a combination of these).
The ammonia detection devices in a gas sample may include a sensing element that includes a first region comprising a p-type metal / oxide / semiconductor (MOS) material and a second region comprising an n-type MOS material. The first region is adjacent to and in contact with the second region (for example, at a diffuse p-n heterojunction formed at an interface between the first and second regions). The p-type MOS material may comprise NiO. In some embodiments, the p-type MOS material may be NiO. The n-type MOS material may comprise 1'Ιη2θ3. In some embodiments, the n-type MOS material may be In2O3.
In other embodiments, the p-type MOS material may be selected from CO 3 O 4, Cr 2 O 3, Mn 3 O 4 or a combination thereof; and the n-type MOS material may be selected from ZnO, WO 3, SnO 2, TiO 2, Fe 2 O 3 or a combination thereof. In other embodiments, the p-type MOS material does not include NiO and the n-type MOS material does not include In203.
The detection device may further comprise one or more electrodes established and separated from each other within the first region and one or more electrodes established and separated from each other within the second region. In some embodiments, the sensing device may include a first electrode within the first region, a second electrode within the second region, and wiring interconnecting the first and second electrodes. Resistance measured along the wiring may indicate the presence of NH3 in a gas interfacing with the sensing element.
In some embodiments, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the measured resistance is not affected by the presence of a gas other than ammonia (e.g., a disruptive gas such as CO, NO, a hydrocarbon or a combination thereof) which is also present in the gas sample interfacing with the sensing element.
In some cases, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are chosen so that the measured resistance is not affected by the presence of a of several hydrocarbons, such as one or more aromatic hydrocarbons (e.g., toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), one or more functional organic compounds (e.g., acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, methylfuran, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof), or a combination thereof. In some embodiments, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the measured resistance is not affected by the presence of 50 ppb at 5 ppm of one or more hydrocarbons, such as one or more aromatic hydrocarbons (eg, toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g. hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), one or more functional organic compounds (eg, acetone, acetonitrile, ethyl acetate, methylvinylketone, ethanol, 2-methylfuran, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof), or a combination thereof. .
In some embodiments, the sensing element defines a length from a first side to a second opposite side, the first side being defined by an edge of the first region opposite the second region, the second side being defined by an edge of the second region opposite the first region, and the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the wiring includes a combined amount of the p-type MOS material and n-type MOS material in the length direction which is predetermined to generate a measured resistance indicating the presence of NH3 in a gaseous sample interfaced with the sensing element. The predetermined combined amount can be chosen such that the measured resistance is not affected by the presence of a gas other than ammonia (for example, a disruptive gas such as CO, NO, a hydrocarbon or a combination of these) which is also present in the gaseous sample interfaced with the detection element. In some cases, the predetermined combined amount may be chosen such that the measured resistance is not affected by the presence of one or more hydrocarbons, such as one or more aromatic hydrocarbons (eg, toluene, o-xylene or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), one or more functional organic compounds (For example, acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methyl furane, hexanal, methacrolein, 1-propanol, 2-propanol, or combination thereof), or a combination thereof. In some embodiments, the predetermined combined amount may be selected such that the measured resistance is not affected by the presence of 50 ppb at 5 ppm of one or more hydrocarbons, such as one or more aromatic hydrocarbons (e.g. toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof ), one or more functional organic compounds (for example, acetone, acetonitrile, ethyl acetate, methylvinylketone, ethanol, 2-methylfuran, hexanal, methacrolein, 1-propanol , 2-propanol, or a combination thereof), or a combination thereof.
In some embodiments, the detection device may further include a third electrode within the first region, a fourth electrode within the second region, and wiring interconnecting the third and fourth electrodes. A resistance measured along the wiring interconnecting the third and fourth electrodes in comparison with the resistance measured along the wiring interconnecting the first and second electrodes indicates a concentration of NH3 in a gas interfacing with the sensing element.
In some embodiments, the device may further include a platform assembly holding the first and second electrode in an array of electrode wires selectively in contact with the sensing element. The platform assembly may be adapted to selectively modify a contact location of the first electrode within the first region and selectively modify a contact location of the second electrode within the second region. The platform assembly may be adapted to selectively change a distance between the first electrode and the second electrode.
Detection systems are also provided for detecting ammonia in a gas sample. The detection system may include a sensing device that includes a sensing element, a first electrode established within the first region, a second electrode established within the second region, and a database. The sensing element may comprise a first region comprising a p-type MOS material and a second region comprising an n-type MOS material. The first region is adjacent to and in contact with the second region (for example, at a diffuse p-n heterojunction formed at an interface between the first and second regions). The p-type MOS material may comprise NiO. In some embodiments, the p-type MOS material may be NiO. The n-type MOS material may comprise In203. In some embodiments, the n-type MOS material may be In203. In other embodiments, the p-type MOS material may be selected from CO 3 O 4, Cr 2 O 3, Mn 3 O 4 or a combination thereof; and the n-type MOS material may be selected from ZnO, WO 3, SnO 2, TiO 2, Fe 2 O 3 or a combination thereof. In other embodiments, the p-type MOS material does not include NiO and the n-type MOS material does not include In203.
In some embodiments, the system may be designed to estimate the concentration of NH3 in a biological sample, such as human breath. For example, the system may be designed to detect and / or quantify ammonia at concentrations up to 5,000 ppb (for example, at concentrations of 50 ppb to 2,000 ppb, at concentrations of 50 ppb to 1 000 ppb, or at concentrations of 50 ppb to 500 ppb) in a human breath sample. In other embodiments, the system may be designed to estimate the concentration of NH3 in a flue gas. In other embodiments, the system may be designed to estimate the NH3 concentration in an environmental sample.
The database may correlate the resistance measured along the wiring between the first electrode and the second electrode with the presence of NH3 in a gaseous sample interfaced with the sensing element. In some embodiments, the database may further correlate an estimate of an NH3 concentration in the gas sample based on the measured resistance. In some embodiments, the database may include a calibration curve for NH3.
In some embodiments, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the measured resistance is not affected by the presence. a gas other than ammonia (eg a disruptive gas such as CO, NO, a hydrocarbon or a combination thereof) that is also present in the gaseous sample interfaced with the detection. In some cases, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected so that the measured resistance is not affected by the presence of one or more hydrocarbons, such as one or more aromatic hydrocarbons (e.g., toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, Isoprene, 3-methylpentane, or a combination thereof), one or more functional organic compounds (for example, acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methylfuran, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof), or a combination thereof. In some embodiments, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the measured resistance is not affected by the presence. from 50 ppb to 5 ppm of one or more hydrocarbons, such as one or more aromatic hydrocarbons (e.g., toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g. , hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), one or more functional organic compounds (eg, acetone, acetonitrile, ethyl acetate , methylvinylketone, ethanol, 2-methylfuran, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof), or a combination thereof.
In some embodiments, the sensing element defines a length from a first side to a second opposite side, the first side being defined by an edge of the first region opposite the second region, the second side being defined by an edge. of the second region opposite to the first region, and the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the wiring includes a combined amount of p-type MOS material and n-type MOS material in the length direction which is predetermined to generate a measured resistance indicating the presence of NH3 in a gaseous sample interfaced with the sensing element. The predetermined combined amount can be chosen such that the measured resistance is not affected by the presence of a gas other than ammonia (for example, a disruptive gas such as CO, NO, a hydrocarbon or a combination of these) or a combination thereof, which is also present in the gaseous sample interfaced with the sensing element. In some cases, the predetermined combined amount can be selected so that the measured resistance is not affected by the presence of one or more hydrocarbons, such as one or more aromatic hydrocarbons (eg, toluene, -xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), one or more compounds organic functional (eg, acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methyl furane, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof), or a combination thereof. In some embodiments, the predetermined combined amount may be selected such that the measured resistance is not affected by the presence of 50 ppb at 5 ppm of one or more hydrocarbons, such as one or more aromatic hydrocarbons (eg for example, toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (eg, hexane, pentane, isoprene, 3-methylpentane, or a combination of those one or more functional organic compounds (for example, acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methyl furane, hexanal, methacrolein, propanol, 2-propanol, or a combination thereof), or a combination thereof.
In some embodiments, the detection device may further include a third electrode within the first region, a fourth electrode within the second region, and wiring interconnecting the third and fourth electrodes. A resistance measured along the wiring interconnecting the third and fourth electrodes in comparison with the resistance measured along the wiring interconnecting the first and second electrodes indicates a concentration of NH3 in a gas interfacing with the sensing element.
In some embodiments, the detection system may further include a controller holding the database and electronically associated with the wiring. The controller may include a memory on which are stored: the database; instructions for receiving a plurality of measured resistance values generated by the detection device in the presence of the gas sample; and instructions for estimating an NH3 concentration in the gas sample based on the plurality of measured resistances. In some embodiments, a first measured one of the plurality of measured resistors may correspond to a first distance between corresponding electrodes in the first and second regions, respectively, and a second measured one of the plurality of measured resistors may correspond to a second distance between corresponding electrodes in the first and second regions, respectively, the first distance being different from the second distance. The controller may further include a memory on which are stored instructions for performing appropriate resistance measurements for detecting and / or quantifying NH3 in the gas sample. The controller may further include a memory on which are stored instructions for eliminating (for example, subtracting or otherwise correcting) the influence of a gas other than ammonia (for example, a disruptive gas such as CO, NO, a hydrocarbon or a combination thereof) or a combination thereof, which is also present in the gaseous sample interfaced with the sensing element. For example, this may include one or more calibration curves for possible disrupters (eg, CO, NO, and / or one or more hydrocarbons) in the gas sample.
Optionally, in the case of systems designed to estimate the concentration of NH3 in a biological sample, such as human elixin, the controller may include a memory on which are stored instructions for assigning a score for the progression of an illness. in a patient based on the estimated concentration of NH3 in the gas sample associated with the biological sample from the patient (eg, a breath sample from the patient). For example, the controller may include a memory on which are stored instructions for assigning a score for progression of liver disease in the patient, renal disease in the patient, infection with H. pylori in the patient or halitosis in the patient. The note may be a numerical score evaluating the progression or severity of the disease. Alternatively, the score may be a binary disease indicator (for example, a "positive" or "negative" indicator signifying the presence of an infection, such as H. pylori infection). Optionally, in the case of systems designed to estimate the concentration of NH3 in a biological sample, such as a breath sample, the controller may include a memory on which are stored instructions for selecting one or more processing instructions (e.g. , one or more treatment options) based on the estimated concentration of NH3 in the gas sample associated with the biological sample from the patient (eg, a breath sample from the patient). The controller may include a memory on which are stored instructions for outputting these results for a person administering the test (for example, the patient and / or a physician). In this way, the sensors can be used as place-of-care diagnostic systems to evaluate the incidence and / or progression of liver disease in a patient, renal disease in a patient, H. pylori infection in a patient and / or halitosis in a patient.
There is also provided an ammonia detection method using sensors and MOS p-n heterostructure based systems. The methods may include providing a detection system based on a p-n MOS heterostructure; contacting the detection element of the detection system with a gas sample; measuring a resistance along the wiring between the first electrode and the second electrode, and detecting the ammonia in the gas sample based on the measured resistance. The detection system may include a sensing device that includes a sensing element, a first electrode established within the first region, a second electrode established within the second region, and a database. The sensing element may comprise a first region comprising a p-type MOS material and a second region comprising an n-type MOS material. The first region is adjacent to and in contact with the second region (for example, at a diffuse p-n heterojunction formed at an interface between the first and second regions). The p-type MOS material may comprise any suitable p-type MOS. In some cases, the p-type MOS material may comprise NiO, CuO, CO 3 O 4, Cr 2 O 3, Mn 3 O 4 or a combination thereof. In some embodiments, the p-type MOS material may be selected from NiO, CoO 3 O 4, Cr 2 O 3, Mn 3 O 4, or a combination thereof. In some embodiments, the p-type MOS material may be selected from CO 3 O 4, Cr 2 O 3,
Mn3O4 or a combination thereof. In some embodiments, the p-type MOS material may be selected from NiO, CuO or a combination thereof. In some embodiments, the p-type MOS material may comprise NiO. In some embodiments, the p-type MOS material may be NiO. In other embodiments, the p-type MOS material does not include NiO. The n-type MOS material may comprise any suitable n-type MOS. In some cases, the n-type MOS material may comprise In 2 O 3, SnO 2, ZnO 2, TiO 2, WO 3, ZnO, Fe 2 O 3 or a combination thereof. In some cases, the n-type MOS material may comprise ln 2 O 3, ZnO, WO 3, SnO 2, TiO 2, Fe 2 O 3 or a combination thereof. In some cases, the n-type MOS material may comprise ZnO, WO 3, SnO 2, TiO 2, Fe 2 O 3 or a combination thereof. In some cases, the n-type MOS material may comprise In203, SnO2, ZnO2, TiO2, WO3 or a combination thereof. In some embodiments, the n-type MOS material may comprise In203. In some embodiments, the n-type MOS material may consist of ln203. In other embodiments, the n-type material does not include In203. In one embodiment, the p-type MOS material does not include NiO and the n-type material does not include In2O3.
The database may correlate the resistance measured along the wiring between the first electrode and the second electrode with the presence of NH3 in a gaseous sample interfaced with the sensing element. In some embodiments, the database may further correlate an estimate of an NH3 concentration in the gas sample based on the measured resistance. In some embodiments, the database may include a calibration curve.
In some embodiments, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the measured resistance is not affected by the presence. a gas other than ammonia (eg a disruptive gas such as CO, NO, a hydrocarbon or a combination thereof) that is also present in the gaseous sample interfaced with the detection.
In some embodiments, the sensing element defines a length from a first side to a second opposite side, the first side being defined by an edge of the first region opposite the second region, the second side being defined by an edge of the second region opposite the first region, and the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the cabling includes a quantity combined the p-type MOS material and the n-type MOS material in the length direction that is predetermined to generate a measured resistance indicating the presence of NH3 in a gaseous sample interfaced with the detection element. The predetermined combined amount can be chosen so that the measured resistance is not affected by the presence of a gas other than ammonia (for example, a disruptive gas such as CO, NO, hydrocarbon or combination thereof) which is also present in the gaseous sample interfaced with the sensing element.
In some embodiments, the device of. detection may further comprise a third electrode established within the first region, a fourth electrode established within the second region, and wiring interconnecting the third and fourth electrodes. A resistance measured along the wiring interconnecting the third and fourth electrodes in comparison with the resistance measured along the wiring interconnecting the first and second electrodes indicates a concentration of NH3 in a gas interfacing with the sensing element.
In some embodiments, the detection system may further include a controller holding the database and electronically associated with the wiring. The controller may include a memory on which are stored: the database; instructions for receiving a plurality of measured resistance values generated by the detection device in the presence of the gas sample; and instructions for estimating an NH3 concentration in the gas sample based on the plurality of measured resistances. In some embodiments, a first measured one of the plurality of measured resistors may correspond to a first distance between corresponding electrodes in the first and second regions, respectively, and a second measured one of the plurality of measured resistors may correspond to a second distance between corresponding electrodes in the first and second regions, respectively, the first distance being different from the second distance.
Contacting the sensing element with the gaseous sample may include exposing the sensing element to the gaseous sample for a period of time effective to induce a measured resistance change along the cabling between the sample. first electrode and the second electrode. In some embodiments, contacting the sensing element with the gaseous sample comprises exposing the sensing element to the gaseous sample for a period of time effective to induce a change in resistance in the gas sample. the same direction in both the p-type MOS material and the n-type MOS material. In some embodiments, contacting the sensing element with the gaseous sample comprises exposing the sensing element to the gaseous sample for a period of time effective to induce a decrease in the resistance of the sensing element. p-type MOS material and a decrease in the resistance of the n-type MOS material. For example, contacting the sensing element with the gaseous sample may include exposing the sensing element to the gaseous sample for 30 seconds to five minutes (for example, for 1 to 3 minutes) .
In some embodiments, the methods may further include heating the sensing element to a temperature of 250 ° C to 450 ° C. In some embodiments, the detection of ammonia in the gaseous sample based on the measured resistance includes estimating an NH3 concentration in the gaseous sample based on the measured resistance.
In some embodiments, the NH 3 concentration in the gas sample may be less than or equal to 5,000 ppb (for example, 50 ppb to 2,000 ppb, 50 ppb to 1,000 ppb, or 50 ppb to 500 ppb. ppb). In some embodiments, the gaseous sample may comprise a biological sample, such as a human breath sample. In some embodiments, the gas sample may include a sample of flue gas, such as a sample of a combustion gas from a diesel engine. In some embodiments, the gaseous sample may comprise an environmental sample. In some embodiments, the gaseous sample may comprise a sample from an industrial process.
Detection systems and methods for diagnosing H. pylori infection in a patient are also provided. The detection systems may include a sensing device that includes a sensing element, a first electrode established within the first region, a second electrode established within the second region, and a database. The sensing element may comprise a first region comprising a p-type MOS material and a second region comprising an n-type MOS material. The first region is adjacent to and in contact with the second region (for example, at a diffuse p-n heterojunction formed at an interface between the first and second regions). The p-type MOS material may comprise NiO. In some embodiments, the p-type MOS material may be NiO. The n-type MOS material may comprise In203. In some embodiments, the n-type MOS material may consist of ln203. In other embodiments, the p-type MOS material may be selected from Co304, Cr203, Mn304 or a combination thereof; and the n-type MOS material may be selected from ZnO, WO 3, SnO 2, TiO 2, Fe 2 O 3 or a combination thereof. In other embodiments, the p-type MOS material does not include NiO and the n-type MOS material does not include ln203.
In some embodiments, the system may be designed to estimate the NH3 concentration in a breath sample from a patient. For example, the system may be designed to detect and / or quantify ammonia at concentrations up to 5,000 ppb (for example, at concentrations of 50 ppb to 2,000 ppb, at concentrations of 50 ppb to 1 000 ppb, or at concentrations of 50 ppb to 500 ppb) in a breath sample. The system may further include a mouthpiece adapted to receive a breath sample exhaled by a patient and deliver the sample to the sensing device.
The database may correlate the resistance measured along the wiring between the first electrode and the second electrode with the presence of NH3 in a gaseous sample interfaced with the sensing element. In some embodiments, the database may further correlate an estimate of an NH3 concentration in the gas sample based on the measured resistance. In some embodiments, the database may include a calibration curve for NH3.
In some embodiments, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the measured resistance is not affected by the presence. a gas other than ammonia (for example, a disruptive gas such as CO, NO, a hydrocarbon or a combination thereof) that is also present in the breath sample interfacing with the detection element. In some cases, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are chosen so that the measured resistance is not affected by the presence of a of several hydrocarbons, such as one or more aromatic hydrocarbons (e.g., toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), one or more functional organic compounds (e.g., acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, methylfuran, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof), or a combination thereof. In some embodiments, the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the measured resistance is not affected by the presence. from 50 ppb to 5 ppm of one or more hydrocarbons, such as one or more aromatic hydrocarbons (e.g., toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g. , hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), one or more functional organic compounds (eg, acetone, acetonitrile, ethyl acetate , methylvinylketone, ethanol, 2-methylfuran, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof), or a combination thereof.
In some embodiments, the sensing element defines a length from a first side to a second opposite side, the first side being defined by an edge of the first region opposite the second region, the second side being defined by an edge of the second region opposite to the first region, and the location of the first electrode relative to the first region and the location of the second electrode relative to the second region are selected such that the wiring includes a combined amount of p-type MOS material and n-type MOS material in the length direction that is predetermined to generate a measured resistance indicating the presence of NH3 in a breath sample interfaced with the sensing element. The predetermined combined amount can be chosen so that the measured resistance is not affected by the presence of a gas other than ammonia (for example, a disruptive gas such as CO, NO, hydrocarbon or combination thereof) or a combination thereof, which is also present in the gaseous sample interfaced with the sensing element. In some cases, the predetermined combined amount may be chosen such that the measured resistance is not affected by the presence of one or more hydrocarbons, such as one or more aromatic hydrocarbons (eg, toluene, o-xylene or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), one or more functional organic compounds (For example, acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methyl furane, hexanal, methacrolein, 1-propanol, 2-propanol, or combination thereof), or a combination thereof. In some embodiments, the predetermined combined amount may be selected such that the measured resistance is not affected by the presence of 50 ppb at 5 ppm of one or more hydrocarbons, such as one or more aromatic hydrocarbons (e.g. toluene, o-xylene, or a combination thereof), one or more aliphatic hydrocarbons (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof ), one or more functional organic compounds (for example, acetone, acetonitrile, ethyl acetate, methylvinylketone, ethanol, 2-methylfuran, hexanal, methacrolein, 1-propanol , 2-propanol, or a combination thereof), or a combination thereof.
In some embodiments, the detection device may further include a third electrode within the first region, a fourth electrode within the second region, and wiring interconnecting the third and fourth electrodes. A resistance measured along the wiring interconnecting the third and fourth electrodes in comparison with the resistance measured along the wiring interconnecting the first and second electrodes indicates a concentration of NH3 in the breath sample interfacing with the electrode element. detection.
In some embodiments, the detection systems may further include a controller holding the database and electronically associated with the wiring. The controller may include a memory on which are stored: the database; instructions for receiving a plurality of measured resistance values generated by the detection device in the presence of the breath sample; and instructions for estimating an NH3 concentration in the breath sample based on the plurality of measured resistances. In some embodiments, a first measured one of the plurality of measured resistors may correspond to a first distance between corresponding electrodes in the first and second regions, respectively, and a second measured one of the plurality of measured resistors may correspond to a second distance between corresponding electrodes in the first and second regions, respectively, the first distance being different from the second distance. The controller may further include a memory on which are stored instructions for performing appropriate resistance measurements for detecting and / or quantifying NH3 in the breath sample.
The systems may further include a controller that includes a memory on which are stored instructions for assigning a score for the progression of H. pylori infection in the patient. The note may be a digital score evaluating the progression or severity of H. pylori infection in the patient. Alternatively, the score may be a binary indicator of H. pylori infection (e.g., a "positive" or "negative" indicator signifying the presence of H. pylori infection). In one embodiment, the instructions for assigning a score for progression of H. pylori infection may include instructions for providing a "positive" indicator for the presence of H. pylori infection in a patient. when the estimated NH3 concentration in the breath sample is 50 ppb to 400 ppb, and provide a "negative" indicator indicating the absence of H. pylori infection in a patient when the estimated NH3 concentration in the breath sample is 500 ppb at 600 ppb.
The systems may further include a controller that includes a memory on which are stored instructions for performing appropriate resistance measurements for detecting and / or quantifying NH3 in the breath sample, instructions for receiving a plurality of samples. measured resistance values generated by the detection device in the presence of the breath sample; and instructions for estimating an NH3 concentration in the breath control sample based on the plurality of measured resistances. The systems may further include a controller that includes a memory on which are stored instructions for subtracting the estimated NH3 concentration in the breath sample from the estimated NH3 concentration of the breath sample. This can be used to determine the net change in NH3 concentration in a breath sample of the patient when urea is administered.
In some cases, the systems may further include a controller that includes a memory on which are stored instructions for assigning a score for progression of H. pylori infection to the patient based on the net change in NH3 concentration in a breath sample of the patient during administration of urea. The note may be a digital score evaluating the progression or severity of H. pylori infection in the patient. Alternatively, the score may be a binary indicator of H. pylori infection (e.g., a "positive" or "negative" indicator signifying the presence of H. pylori infection). In one embodiment, the instructions for assigning a score for progression of H. pylori infection may include instructions for providing a "positive" indicator for the presence of H. pylori infection in a patient. when the net change in NH3 concentration in a patient's breath sample when administered with urea is 50 ppb to 400 ppb, and to provide a "negative" indicator indicating the absence of an infection by H. pylori in a patient when the net change in NH3 concentration in a patient's breath sample when administered urea is 500 ppb at 600 ppb.
Optionally, the controller may further include a memory on which are stored instructions for selecting one or more processing instructions (e.g., one or more processing options) based on the estimated NH3 concentration in the sample. Breath and / or net change in NH3 concentration in a breath sample of the patient when administering urea. The controller may include a memory on which are stored instructions for outputting these results to a person using the system to diagnose H. pylori infection in a patient (eg, the patient and / or a physician). In this way, the systems can be used as place-of-care diagnostic systems to evaluate the incidence and / or progression of H. pylori infection in a patient.
Methods for diagnosing H. pylori infection in a patient may include administering urea (eg, unlabeled urea) to a patient, collecting a breath sample from the patient and measuring the NH3 concentration in the breath sample using the sensors and systems described herein. In one example, the NH3 concentration in the breath sample can be measured using a system described herein that is specifically designed to evaluate the incidence and / or progression of H. pylori infection in a patient. The methods may further include collecting a breath sample sample from the patient prior to administration of urea (eg, unlabeled urea) to the patient, and measuring the concentration of NH3 in the patient. breath sample using the sensors and systems described in this document. In these situations, the methods may involve subtracting the estimated NH3 concentration in the breath sample from the estimated NH3 concentration in the breath sample to determine the net change in NH3 concentration in a sample. patient's breath when administering urea. The net change in NH3 concentration in a patient's breath sample during urea administration can be used to assess the incidence and / or progression of H. pylori infection in a patient. Description of the drawings
FIG. 1A is a plot of the X-ray diffraction pattern of an annealed NiO powder at 320 ° C.
Fig. 1B is a SEM micrograph taken from a NiO film on the sensor.
Figure 1C is a plot of the XPS spectra of the Ni 2p region (top) and the 0s region (bottom) for an annealed NiO powder at 320 ° C.
Fig. 2A is a plot of the X-ray diffraction pattern of an annulus of Ann203 annealed at 320 ° C.
Figure 2B is an SEM micrograph taken from an In203 film on the sensor.
Figure 2C is a plot of the XPS spectra of the Ni 2p region (top) and the O ls region (bottom) for an In203 powder annealed at 320 ° C.
Figure 3 is a schematic representation of the multi-step process used to make the sensors described herein.
Figure 4A is a schematic of the sensors described herein.
Figure 4B is a photograph of the uncoated sensor substrate having four gold wires (left) and an adjacent NiO and In203 sensor (right).
Figure 4C is an SEM image of a side view of the sensor.
Figure 4D is a plot of the I-V characteristics across the NiO and In203 interface at 20% O2 / N2 at 300 ° C, scan rate = 0.1 V / s.
Figure 5A is an SEM image of the interface between NiO (top) and In203 (bottom).
Figure 5B is a Raman spectrum of the NiO side.
FIG. 5C is a Raman spectrum on the Ιη2θ3 side.
Figure 5D is a plot of integrated Raman intensities obtained by mapping from the In203 side to the NiO side (In203: straight line with square markers, NiO: dashed line with circular markers).
Figure 6A is a plot of the gas detection characteristics of NiO when exposed to 1 ppm NH3 at 300 ° C with an exposure time of 10 minutes (20% O 2 / N 2 as background) .
Figure 6B is a plot of gas detection characteristics of NiO when exposed to 1 ppm NH3 at 300 ° C with an exposure time of 2 minutes (20% O 2 / N 2 as background) .
Figure 6C is a plot of the gas detection characteristics of NiO when exposed to 1 ppm NH3 at 500 ° C with an exposure time of 10 minutes (20% O 2 / N 2 as the background atmosphere) .
Figure 6D is a plot of the gas detection characteristics of NiO when exposed to 10 ppm NH3 at 300 ° C with an exposure time of 10 minutes (20% O 2 / N 2 as background) .
Figure 7A is an infrared in situ spectrum of NiO at 300 ° C exposed to 1 ppm NH3.
Figure 7B is an infrared in situ spectrum of NiO at 300 ° C exposed to 10 ppm NH3.
Figure 7C is a plot of the relative height of the peak of the band at 12 67 cm-1 for 1 ppm (straight line) and 10 ppm (dashed line) of NH3 as a function of time (in minutes).
Figure 8A is a plot showing gas detection characteristics of detection channel 1 (CH1, In2O3) for various concentrations of CO at 300 ° C (20% O2 / N2 as background).
Figure 8B is a plot showing gas detection characteristics of detection channel 2 (CH2, NiO) for various concentrations of CO at 300 ° C (20% O 2 / N 2 as background).
Figure 8C is a plot showing gas detection characteristics of detection channel 3 (CH3, In203-Ni0) for various concentrations of CO at 300 ° C (20% O 2 / N 2 as background).
Figure 9A is a plot showing gas detection characteristics of detection channel 1 (CH1, In203) for various concentrations of NO at 300 ° C (20% O 2 / N 2 as background).
Figure 9B is a plot showing gas detection characteristics of detection channel 2 (CH2, NiO) for various concentrations of NO at 300 ° C (20% O 2 / N 2 as background).
Figure 9C is a plot showing gas detection characteristics of detection channel 3 (CH3, In203-Ni0) for various concentrations of NO at 300 ° C (20% O 2 / N 2 as background).
Figure 10A is a plot showing gas detection characteristics of detection channel 1 (CH1, In203) for various concentrations of NH3 at 300 ° C (20% O2 / N2 as background). . Figure 10B is a plot showing gas detection characteristics of detection channel 2 (CH2, NiO) for various concentrations of NH3 at 300 ° C (20% C> 2 / N2 as background).
Figure 10C is a plot showing gas detection characteristics of detection channel 3 (CH3, In203-Ni0) for various concentrations of NH3 at 300 ° C (20% O2 / N2 as background).
Figure 11A is a plot showing gas detection characteristics of detection channel 1 (CH1, In203) for various concentrations of the NH3 / CO mixture at 300 ° C (20% O2 / N2 as background).
Figure 11B is a plot showing gas detection characteristics of detection channel 2 (CH2, NiO) for various concentrations of the NH3 / CO mixture at 300 ° C (20% O2 / N2 as background).
Fig. 11C is a plot showing gas detection characteristics of detection channel 3 (CH3, In203-Ni0) for various concentrations of the NH3 / CO mixture at 300 ° C (20% O2 / N2 as background) .
Figure 12A is a diagram illustrating a simulated breathing system using a steam bath at 37 ° C.
Figure 12B is a diagram illustrating a simulated breathing system using a moisture trap with respiration as the background atmosphere.
Figure 12C is a diagram illustrating a simulated breathing system using a moisture trap with air as the background atmosphere.
Fig. 13A is a plot showing gas detection characteristics of detection channel 3 (CH3, In203-Ni0) for a breath sample containing various concentrations of NH3 at 300 ° C obtained using a simulated breathing system equipped with a steam bath at 37 ° C.
Fig. 13B is a plot showing gas detection characteristics of detection channel 3 (CH3, In2C> 3-NiO) for a breath sample containing various concentrations of NH3 at 300 ° C obtained using a simulated respiration system equipped with an ice bath.
Fig. 13C is a plot showing gas detection characteristics of detection channel 3 (CH3, In203-Ni0) for a breath sample containing various concentrations of NH3 at 300 ° C obtained using a simulated breathing system equipped with a dry ice / acetonitrile moisture trap.
Figure 13D is a calibration curve for the relative changes in resistance (R0 / R) of detection channel 3 (CH3, In2C> 3-NiO) for various concentrations of NH3 added to a breath sample (sample of breath without added NH3 used as background atmosphere).
Figure 14A is a plot showing gas detection characteristics of detection channel 3 (CH3, In203-Ni0) initially for breath sample B, which is then supplemented with various concentrations of NH3 (10 to 1000 ppb ) at 300 ° C obtained using a simulated breathing system equipped with a dry ice / acetonitrile moisture trap.
Figure 14B is a calibration curve for the relative changes in resistance (R0 / R) of detection channel 3 (CH3, In2C> 3-NiO) for various concentrations of NH3 in the breath sample B (air as background atmosphere).
FIG. 15 is a plot showing the gas detection characteristics of all detection channels (CH1 (In203), CH2 (NiO), CH3 (In2O3-NiO)) for a breath sample containing various concentrations of NH3 at 300. ° C with a water bath at 37 ° C.
FIG. 16 is a plot showing the gas detection characteristics of all the detection channels (CH1 (In203), CH2 (NiO), CH3 (In2O3-NiO)) for a breath sample containing various concentrations of NH3 at 300 ° C with a moisture trap in an ice bath.
Fig. 17 is a plot showing gas detection characteristics of all detection channels (CH1 (In203), CH2 (NiO), CH3 (In2O3-NiO)) for a breath sample containing various concentrations of NH3 at 300 ° C with a dry ice / acetonitrile moisture trap.
Figure 18A is a plot of the infrared spectrum of exposed NH3 of NH3 at 300 ° C under oxygen background and then cooled to room temperature.
Figure 18B is a plot of the infrared spectrum of NiO exposed to NH3 at 300 ° C under background N2 and then cooled to room temperature.
Fig. 19 is a schematic illustration of a detection device and a detection system.
Fig. 20 is a schematic illustration of a detection device and a detection system containing electrodes.
Fig. 21 is a schematic illustration of a detection device and detection system containing NiO and In203.
detailed description
Detection devices and corresponding detection systems are provided herein that utilize a semiconductor oxide-based p-n heterojunction. The devices and systems described herein may be used to detect and / or quantify the amount of NH3 in a gas sample. In some cases, the devices and systems described herein may be used to detect and / or quantify the amount of NH3 in a gaseous sample in the presence of other gases, such as CO, NO, or a combination of those -this. The sensors described herein include n-type and n-type materials adjacent to one another to form the sensing element of the sensing device. In this respect, the techniques for obtaining data from the detection device thus constructed can help to distinguish between NH 3 and a mixture of gases, and make it possible to detect and / or quantify the NH 3 in the presence of a or several interfering gases, such as CO, NO, or a combination thereof.
In some cases, sensors and systems can be used to detect and / or quantify ammonia in the presence of one or more hydrocarbons, such as an aromatic hydrocarbon (e.g., toluene, o-xylene, or combination thereof), an aliphatic hydrocarbon (e.g., hexane, pentane, isoprene, 3-methylpentane, or a combination thereof), a functional organic compound (e.g., acetone , Acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methyl furan, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof ), or a combination thereof. In some embodiments, the sensors and systems can be used to detect and / or quantify ammonia at concentrations of less than or equal to 5,000 ppb (for example, at concentrations of 50 ppb to 2,000 ppb, at concentrations of 50 ppb at 1000 ppb, or at concentrations of 50 ppb at 500 ppb) in the presence of one or more hydrocarbons, such as an aromatic hydrocarbon (eg, toluene, o-xylene, or a combination thereof thereof), an aliphatic hydrocarbon (e.g., hexane, pentane, isoprene, 3-methyl-pentane, or a combination thereof), a functional organic compound (e.g. acetone, acetonitrile, ethyl acetate, methyl vinyl ketone, ethanol, 2-methyl furane, hexanal, methacrolein, 1-propanol, 2-propanol, or a combination thereof) , or a combination of these).
An exemplary detection device (10) is schematically illustrated in Fig. 19. The detection device (10) may comprise a detection element (11) similar to a detection MOS element, but formed by at least two discrete MOS materials . That is, the sensing element (11) comprises a first n-type MOS material region (12) and a second p-type MOS material region (14). A diffuse p-n junction (16) may be established between the n-type region (12) and the p-type region (14). The n-type and p-type regions (12, 14) are formed immediately adjacent one another and can contact each other at the p-n junction (16). Electrodes or other electrical wire bodies (generally identified by 17) are, or may be, selectively or permanently established at nodes within each of regions 12, 14 (eg, gold electrodes). equipped with a network of gold microressorts (not shown)). Electrical connections (e.g., wires) may be established between selected pairs of electrodes or nodes (17) thus established, with Figure 19 illustrating three possible connections as measured resistors RP, RN and RPN. RP represents a resistance measured between two nodes (17) only in the p-type region (12). RN represents a resistance measured between two nodes (17) only within the n-type region (14). RPN represents a measured resistance across both p and n-type regions 12, 14 (e.g., electrodes 17a and 17b of Fig. 19). In one embodiment, a platform (not shown) supports the sensing element (11) and can be maintained at a temperature optimized for the analyte.
The detection device (10) can be provided as part of a detection system (18) as described herein. The detection system (18) may comprise components conventionally used with MOS gas detection systems, such as a housing (not shown) for directing a gas or other substance of interest through the element. detection apparatus (11), electronic apparatuses for establishing and measuring conductivity at the desired connections (for example, RP, RN, RPN) and a controller 19 (for example, a computer or other logical device) for receive and / or interpret the measured conductivity signals. In some embodiments, a measuring device (for example, a multimeter) may be provided, outside the controller 19, which measures resistance at the connection or selected connections, and transmits the measured value (s). to the controller 19 for interpretation purposes as described below. In some embodiments, the detection system 18 may be provided as a single unit, such as a portable device providing an inlet port through which a gas sample is introduced. In any case, the controller 19 may further be programmed to determine the presence and amount (for example, in ppm or ppb) of one or more analytes of interest (for example, ammonia) on the basis of the measured conductivity signals. In some embodiments, the controller 19 may be programmed to operate the sensing device 10 and analyze the generated data to detect the presence of ammonia and estimate its concentration in various sample types, including samples of Human breath and flue gas samples. In other embodiments, some or all of the interpretation of the measured resistances can be performed manually, so that the controller 19 may be optional.
The p-type material region 12 comprises a p-type MOS material which is conductive, positive holes being the major part of the charge carriers. Generally, in the presence of an oxidizing gas, the conductivity of the MOS type materials increases (or their resistivity decreases). An opposite effect is generally observed with the p-type MOS material in the presence of a reducing gas. However, in the case of NiO, a transient decrease in resistance when exposed to low levels of NH3 can be observed. This effect can be exploited to amplify the response of the sensors described in this document vis-à-vis ammonia. The p-type MOS material may comprise NiO. In some embodiments, the p-type MOS material may comprise at least 75% by weight of NiO (for example, at least 80% by weight of NiO, at least 85% by weight of NiO, at least 90% by weight of NiO, at least 95% by weight of NiO, at least 96% by weight of NiO, at least 97% by weight of NiO, at least 98% by weight of NiO or at least 99% by weight of
NiO) based on the total weight of the p-type MOS material. In some embodiments, the p-type MOS material may be NiO.
The n-type material region (14) comprises an n-type MOS material in which the major part of the charge carriers are electrons. Generally, during its interaction with an oxidizing gas, the conductivity of the n-type MOS material decreases (or its resistivity increases). An opposite effect is observed with the n-type MOS material in the presence of a reducing gas. The n-type MOS material may comprise ln203. In some embodiments, the n-type MOS material may comprise at least 75% by weight of In203 (eg, at least 80% by weight of Ιη2θ3, at least 85% by weight of In2C> 3, at at least 90% by weight In203 or at least 99% by weight of In203) based on the total weight of the n-type MOS material. In some embodiments, the n-type MOS material may be In2C> 3.
In other embodiments, the p-type MOS material may be selected from NiO, CO3O4, Cr203, Μη304 or a combination thereof; and the n-type MOS material may be selected from In203, ZnO, WO3, SnO2, TiO2, Fe2O3 or a combination thereof. In some embodiments, the p-type MOS material may be selected from Co304, Cr203, Mn3O4 or a combination thereof; and the n-type MOS material may be selected from ZnO, WO 3, SnO 2, TiO 2, Fe 2 O 3 or a combination thereof. In some embodiments, the p-type MOS material does not include NiO. In some embodiments, the n-type MOS material does not include In203. In one embodiment, the p-type MOS material does not include NiO and the n-type MOS material does not include In203.
The conductivities measured at the p-type RP region, at the n-type RN region and across the pn pn junction can be evaluated to determine the presence and amount of a particular gas, such as ammonia. because different conductivity changes are expected in each of these regions when exposed to a gas such as NH3. Signal analysis may take a variety of forms, and may include obtaining a plurality of p-n junction measurements at different nodes within the p-type region and the n-type region. For example, Fig. 20 illustrates an alternative topology of wires or nodes (and corresponding electrical connections or wires) along the sensing device 10 and will help explain in more detail the basis for the identification of an analyte on the basis of a cancellation concept. With an appropriate combination of the p-type material in the p-type region 12 and the n-type material in the n-type region 14, using one of the conductive wires from the electrodes or nodes at RPi (26) , at Rp2 (30), at RP3 (32), at RPn (34) in the p-type region 12 and other conductive wires from the electrodes or nodes at Rni (36) at Rn2 (40), at RN3 (42), at RNn (44) in n-type region 14, the analyte signal may decrease completely and may be treated as a null response 1 particular analyte. Thus, different types of analyte molecules will have unique zero response spacings. For example, a first analyte may have zero response spacing between RPi (26) and Rni (36), a second (different) analyte may have zero response spacing between RP2 (30) and RN2 (40), and so on.
With the above in mind, it should be noted that zero response data can be used as a "fingerprint" signature that is unique to a specific analyte. Therefore, in a blind study, sensors and systems can elucidate the identity of analytes using this "fingerprint" signature technique. For example, the controller 19 (Fig. 19) may be programmed to include a database of various analytes and their corresponding previously determined null response data; the controller 19 may compare the conductivity information (e.g., zero gap data) of an unknown analyte to be tested to the database to identify the unknown analyte.
With these principles in mind, an example of an ammonia sensor incorporating NiO as a p-type material and 1'Ιη2θ3 as n-type material is shown schematically in Figure 21. In the schematic illustration, the device detector 50 comprises a NiO p 52 material and an In2C> 3 n 54 material and, unexpectedly, it is found to be very sensitive to NH3 and capable of discrimination against CO and NO. The illustrated electrode wires extend from the electrodes or nodes 56 and 58 into the p-type material 52 and extend from the electrodes or nodes 60 and 62 into the n-type material 54. The channels 1, 2 and 3 ("CH1" to "CH3") 64, 66, 68 are illustrated between the wire of the electrode 60 and the wire of the electrode 62, between the wire of the electrode 56 and the wire of the electrode 58, and between the wire of the electrode 56 and the wire of the electrode 62, respectively.
The resistance measured at each of the channels 64 to 68 differs in the presence of NH3, NO or CO, and varies depending on the concentrations of NH3, NO or CO. By way of example, Figure 8A is a plot of the measured resistance obtained from channel 1 64 in response to 20% O 2 / N 2 combinations with various CO concentrations (1, 3 and 10 ppm CO ). A decrease in resistance was observed at CO concentrations of 1, 3 and 10 ppm, with higher concentrations inducing a gradual decrease in the signal. Figure 8A is a plot of the measured resistance obtained from channel 266 in response to combinations containing 20% O 2 / N 2 with various CO concentrations (1, 3 and 10 ppm CO). An increase in resistance was observed at NO concentrations of 1, 3 and 10 ppm, with higher concentrations inducing a gradual increase in the signal. FIGS. 8A and 8B can be compared to FIG. 8C which shows a plot of the measured resistance obtained from channel 388 in response to combinations containing 20% O 2 / N 2 with various concentrations of CO (1, 3 and 4). 10 ppm CO). The CO signal at 1 and 3 ppm disappears completely and a very small signal is observed with 10 ppm CO. Similar results were obtained for NO (see Figures 9A-9C).
In the case of NH3 (see Figures 10A to 10C), a decrease in resistance was observed at NH3 concentrations of 1 ppm, 0.5 ppm and 0.1 ppm from the three channels when short pulses of gaseous sample (for example, lasting 2 minutes) were used, higher concentrations inducing a progressive decrease of the signal. Significantly, even at very low NH3 concentrations (eg, 100 ppb), the response remains important for channel 3 68. The response on NH3 exposure increased by exposure of the sensor to NH3 for relatively short periods of time, as described in detail in Example 1. For example, the sensor may be exposed to NH3 for intervals of from 30 seconds to five minutes (for example, from 1 to 3 minutes, or for about 2 minutes). minutes) . When exposing the sensor to NH3 for short time intervals, both the NiO and the In203 (channels 1 and 2) exhibit a decrease in resistance, so that the detection data that combines the two oxides (channel 3) have an additive effect, by amplifying the response from NH3 (FIGS. 10A-10C), whereas with CO and NO, the opposite response results in a cancellation of the signal (FIGS. 8A-8C, 9A-9C) . This strategy makes it possible to detect and / or quantify NH3 at concentrations <1000 ppb (for example, from 50 ppb to 1000 ppb) in the presence of CO (and / or NO and / or hydrocarbons), such as it can be seen in FIGS. 11A to 11C.
With the above explanations in mind, detection devices (and corresponding detection systems) can be used to effectively detect the presence and concentration of NH3, including discrimination against the presence of CO and / or NO and / or hydrocarbons, as described above.
As described below, non-limiting examples of NH 3 detection devices according to some embodiments of the present disclosure have been constructed and tested to confirm that their ability to detect NH 3 was viable, including their ability to detection of NH3 in human breath.
Examples
Example 1: Selective Detection of Ammonia at Partial Bp Levels Using a P-n Semiconductor Oxide Heterostructure
The detection of low levels of ammonia is of interest for applications related to the environment, combustion and health. Resistive semiconductor metal oxide detection platforms can be used to detect ammonia and other gases. Two important aspects of gas detection are enhancement of sensitivity and improvement of selectivity. A detection platform comprising n-type αη2θ3 and p-type NiO placed side by side with a 30 μm shared interface was studied. The substrate on which these metal oxides are placed makes it possible to measure the change in resistance through In2C> 3, NiO or any combination of these two oxides. With low NH3 concentrations (<100 ppb), the resistance change with NiO was abnormal at 300 ° C, the resistance decreased and then gradually increased for several tens of minutes before decreasing again to reach the baseline. In situ diffuse infrared spectroscopy showed a 1267 cm-1 band, which was attributed to 02 ~, and the change in intensity of this band over time reflected the transient resistance change with 1 ppm NH3 at 300 ° C, indicating that chemical adsorption of NH3 correlated with 02 species. By taking advantage of the transient decrease in NiO resistance with NH3 and combining In203 and NiO, the. The selectivity could be improved with regard to NH3 at concentrations as low as 100 ppb. Interference with CO, NOx and moisture were studied. By choosing an appropriate combination of the two oxides, the response to CO at less than 10 ppm could be canceled. Similarly, with NO at less than 10 ppb, the sensor response was minimal. The sensor was used to analyze NH3 mixed with human breath at concentrations of 10 to 1000 ppb. Water had to be completely removed from the breath by means of a moisture trap because the water interferes with the chemical absorption chemistry of NH3. Potential applications of this detection platform in breath analysis are discussed.
In this document, ammonia sensors with a sensitivity of the order of ppb, which may possibly be used for the analysis of the breath, are studied.
Introduction
Methods for measuring ammonia (NH3) are of interest to industries related to the environment, combustion and health. Ammonia in the atmosphere comes mainly from anthropogenic sources, including agriculture (nitrogen fixation, ammonification) and emissions from the chemical industry involved in the development of refrigeration and fertilizers. Ammonia is a tear gas, and breathing high concentrations of ammonia (~ 1000 ppm) can induce laryngeal spasms and bronchiectasis. Therefore, there is a need for ammonia monitoring devices in the environment. The transportation industry is also interested in the measurement of ammonia in exhaust emissions, the control of air quality in the passenger compartment and by a new generation of lean-burn engines, where. the exhaust gas after treatment comprises reacting the nitrogen oxides with ammonia. The human body also produces ammonia, and monitoring of ammonia in exhaled human breath has potential applications in health centers (for example, to diagnose disease). For example, the measurement of ammonia in the breath can be used to search for several diseases, including liver and kidney malfunction, H. pylori infection and halitosis. The concentration ranges on which ammonia detection is appropriate for these applications range from 0.1 ppm (health) to several hundred ppm (environment).
Different measurement principles have been applied for the detection of ammonia, such as optical spectroscopy, electrochemistry and wet chemistry. A particularly difficult application is the detection of ammonia in human breath. Tunable laser diode absorption spectroscopy was used to detect ammonia in the breath, with a detection limit of 1 ppm. A quantum cascade laser diode was able to measure ammonia at a rate as low as 4 ppb. Other strategies include the use of a quartz crystal microbalance and a liquid film conductive sensor. Sensors based on conductive polymer junctions can detect ammonia at concentrations of - ppb in the human breath, and it is reported that a pno-based poly-thioline based heterojunction sensor sensitivity of the order of the ppt. Mass spectrometry can also measure ammonia up to levels of the order of ppb. Instruments for measuring ammonia are often bulky, and more and more attempts are being made to obtain miniaturized sensors.
Electrochemical semiconductor sensors have been developed to monitor ammonia. This technology is attractive because it is possible to obtain a high sensitivity, a selectivity and a fast response time. In addition, these devices have the advantages of consuming little energy, being light, having low maintenance costs, tolerating harsh environments and being portable. There are many articles on resistive semiconductor metal oxide sensors for ammonia. The working principle of these devices is associated with the adsorption of gaseous molecules on the surface of the oxide to induce a charge transfer, which results in a change of resistance of the oxide. Semiconducting metal oxides, such as the n-type oxides WO 3, SnO 2, Ιη 2 O 3, ZnO, TiO 2, M0O 3, and the p-type oxides
Cr2C> 3, NiO, CuO, were studied as detection material to detect NH3. To improve sensitivity and selectivity, noble metals such as Pt, Pd, Au and Ag have been introduced into metal oxides. Of these, M0O3-based sensors have been developed for measuring ammonia in human breath.
However, the development of an electrochemical detection platform capable of measuring low concentrations of ammonia in the environment, in optimized combustion processes, and in human breath is still a challenge. There is a need for a sensitivity of the order of ppb, for discrimination against other gases present at much higher concentrations and, in the case of combustion, for the ability to tolerate difficult environments and be insensitive to other exhaust gases.
Mixtures of p and n semiconductor oxides can improve the performance of the sensors. Examples include anatase / rutile for the detection of CO, ZnO / NiO for the detection of NH3, In203 / Ni0 for the detection of ethanol and Cu0 / SnO2 for the detection of H2S. These designs are mixtures of p and n powders, or p-type material formed on n-type powders and vice versa. In addition, isotype hetero-junctions prepared by the powder mixture, such as WO3 and ZnO, are also capable of selectively detecting gases.
A detection device is provided herein which includes an adjacent array of p-type NiO and n-type In2O3 deposited on a gold microressort array. This semiconductor heterojunction structure can be used to detect ammonia at levels of the order of ppb, while allowing discrimination against nitric oxide at rates of the order of ppb and carbon monoxide at significantly higher ppm concentrations. The potential application of ammonia detection in human breath samples is also demonstrated, suggesting the application of this sensing platform in a future breath monitoring device.
Experimental part
Chemicals and Materials Indium (II) oxide (99.99% metal base, -325 mesh powder), nickel (II) oxide (99.998% metal base), alpha -terpineol (96%), the gold threads (0.127 mm diameter, 99.99%) were purchased from Alfa Aesar (Ward Hill, USA). Plastic substrates with gold micro-springs were obtained from FormFactor, Inc. (USA). Interdigitated electrodes were obtained from Case Western Reserve University. All gases tested, including nitrogen, oxygen, ammonia and carbon monoxide, were provided by Praxair (Danbury, USA).
Sensor manufacturing
The sensor manufacturing procedures are shown in FIGS. 3A-3D and 4A-4D. The plastic substrates were washed with ethanol and distilled water. The gold wires were connected to the gold micro-springs of the substrate. Commercial powders were milled thoroughly before being used. 1 g of NiO powder was dispersed in 0.4 ml of terpineol and mixed to obtain a slurry. 80 mg of the NiO suspension obtained were uniformly deposited by painting on the left side of the substrate. Then, 1 g of In203 powder was mixed with 0.4 ml of terpineol and 20 mg of the suspension was deposited by painting on the right side of the substrate with a common interface. According to the surface divided by the vertical lines of four gold microressorts, the ratio of surfaces thus produced of the two semiconductors was found to be 14/4 on the surface of the substrate (17.5 mm χ 4.5 mm) . The substrate has been designed to have a plurality of connection pins at different distances, so that the resistance across different lengths of the oxides can be measured. The sensor was calcined in air at 320 ° C for 2 hours and maintained in a tube oven at 300 ° C with 20% O 2 in N 2 flowing overnight before being tested. The polymer substrate decomposed at 350 ° C, therefore 10 x 10 mm alumina substrates with interdigitated gold tracks spaced 0.25 mm apart were used for high temperature measurements. After calcination at 320 ° C in air for 2 hours, the semiconductor layer was generally about 200 μιη thick (discussed later).
Characterization
The phase and crystallinity of the metal oxides were analyzed with a Bruker D8 Advance X-ray diffractometer. The morphology of the sensor surface was investigated with a Quanta 200 scanning electron microscope. The chemical state of the metal oxides was examined with a Kratos X-ray photoelectron spectrometer with an Al mono-source. The current / voltage measurement was performed on an electrochemical workstation CHI760D. The gas / solid interactions were studied using a PerkinElmer Spectrum 400 FTIR FTIR spectrometer coupled to a diffuse reflection accessory. Raman mapping of the interface was performed on a Raman microprobe from Renishaw - Smiths.
Gas detection measures
All gas detection experiments were performed in a quartz tube placed inside a tube furnace (Lindberg / Blue) at 300 ° C, with a PC-controlled gas supply system. calibrated mass flow controllers (Sierra Instruments INC.). Gaseous mixtures tested containing different concentrations of 20% by volume constant oxygen NH3 were prepared by diluting NH3 with O2 and N2. The total flow rate was maintained at 200 cc / minute. Sensor resistance was recorded by an Agilent 34972A LXI data switching / data acquisition unit or HP34970A at a 0.1 Hz scan rate.
Human breath detection measures
A system simulating a human breath containing gaseous ammonia in a trace state has been developed. The system includes a Mylar bag containing exhaled human breath samples and a bottle of ammonia gas. Trace ammonia gas at physiologically appropriate concentrations was determined by controlling the flow rates of the breath samples from the Mylar bags and the ammonia feed, respectively. The total flow rate was maintained at 200 cc / minute. Three montages have been designed. A first setup used a steam bath at 37 ° C to maintain a constant humidity in the mixture of NH3 and breath sample. The second assembly used a dry ice / acetonitrile bath maintained at -20 to -25 ° C to completely remove moisture from the breath mixture + NH3 and also an ice bath to reduce moisture . In these two montages, the breath sample was used as background and NH3 was introduced into the sample at increasing concentrations. In the third assembly, air was used as the background, and the breath sample was measured, and then increasing amounts of NH3 were added thereto, all gases passing through a moisture trap. at a temperature of -20 to -25 ° C. Results
Characterization
The two semiconductor oxides of interest used in this study (NiO and In203) were obtained from commercial sources. Detailed characterization is shown in FIGS. 1A-1C and 2A-2C for NiO and In2O3 annealed at 320 ° C, respectively.
NiO: The X-ray diffraction pattern (XRD) (Figure IA) is usually typical of the cubic structure of NiO (JCPDS No. 04-0835). Scanning electron microscopy (FIG. 1B) suggests particle diameters of about 200 to 300 nm. X-ray photoelectron spectroscopy (XPS) of the region O ls (Figure 1C) suggests the presence of oxygen network (O2-, binding energy of 529.4 eV), hydroxyl groups (binding energy of 531 eV) , and strongly chemisorbed oxygen (533 eV). In the 2P3 / 2 region of nickel, the peak at 853.7 is attributed to large clusters of ΝίΟε and the peak at 855.8 eV at Ni05 of surface shielded by oxygen and the non-local shield of second neighbor of ΝίΟβ and Ni05. Two peaks at 861.0 eV and 864.5 eV were attributed to the satellite region.
In203: The XRD profile of In203 shown in Figure 2A indicates a cubic crystal structure (JCPDS No. 06-0416). The particle size on the micrograph taken at SEM (FIG. 2B) is less than 100 nm. The XPS (Figure 2C) indicates two peaks at 444.7 and 452.2 eV attributed to the states 3d5 / 2 and 3d3 / 2 of the In, generally of the In3 +. The O ls spectrum is asymmetric with two peaks at 530, 2 and 532.0 eV, the first being attributed to the state of the oxygen network, and the large envelope at 532.0 eV to the oxygen ions of the deficient regions. in oxygen (holidays).
Sensor characteristics
Design: Figure 3 is a schematic of the steps involved in sensor design, and Figures 4A-4D show the characteristics of the sensor. Both oxides are placed adjacent to one another on a plastic substrate and share a common interface. The design of the substrate makes it possible to measure resistances on various lengths of the metal oxides (CHl is defined by In203, CH2 by NiO and CH3 by a combination of the two oxides, the choice of this combination is easily modified on the same sample). Figure 4B shows a photograph of the sensor, with and without the oxide coating. Gold threads are used for resistance measurements. Figure 4C shows a side view of the sensor, indicating that the oxide films have a thickness of ~ 200 μm. These devices are heated at 320 ° C in air for 2 hours, before making measurements at 300 ° C. Figure 4D is a current / voltage (I-V) plot at 300 ° C and shows a linear relationship, indicating that there is no rectification, as would be expected with diffuse mixing of the powders.
Microstructure: FIG. 5A represents a top view taken at the SEM of the NiO / In2C interface> 3. The NiO side of the sensor is characterized by Raman bands at 500, 740, 900 and 1090 cm -1 (FIG. 5B), the most intense bands being at 500 and 1090 cm -1, respectively assigned to the longitudinal optical modes of first and second order. On the In203 side, the bands observed at 307, 366, 494 and 627 cm-1 (FIG. 5C) are consistent with what has previously been described in the literature. The Raman spectra were recorded over a length of 180 μm across the interface and the Raman band intensities of NiO (500 cm-1) and In203 (307 cm-1) are plotted in Figure 5D. There is an intermingling of the two oxides over a distance of ~ 30 pm at the interface.
Electrical Specifications
Figure 6A is a plot of the change in NiO resistance after exposure to 1 ppm NH3 at 300 ° C. With the activation of the gas pulse, there is a decrease in resistance, then a slight increase. After stopping the gas pulse after 10 minutes, the resistance continues to increase for 10 minutes (crosses the baseline), then there is a slight decrease towards the baseline for the next 25 minutes. Figure 6B shows that if the gaseous NH3 pulse lasts only 2 minutes at 300 ° C, a decrease in resistance is only observed, the response and return to the baseline occurring relatively quickly (minutes). A 2 minute exposure was used for all of the detection experiments described below unless otherwise indicated. At a temperature of 500 ° C, an increase in resistance is recorded with 1 ppm NH3 (Figure 6C). Figure 6D shows an increase in resistance for 10 ppm NH3 at 300 ° C.
Infrared spectroscopy
Infrared spectroscopy of the NiO interface was examined after exposure to NH3 at 300 ° C. Figure 7A focuses on the spectral region from 1220 to 1320 cm-1, where changes with 1-10 ppm NH3 were observed.With higher concentrations of NH3 (100 ppm), a band at 3220 cm -1 1 was observed in the presence of oxygen (Figures 18A and 18B) With N 2 passing over the NiO sample, there is no band in the region of 1200 to 1300 cm -1 (Figure 7A). but with 20% oxygen in the background gas, a band at 12 67 cm -1 appears with 1 ppm NH 3, an initial increase of this band is observed (10 minutes) then a progressive decrease (30 minutes) , which is reversed when NH3 is removed with 20% O2 Figure 7B shows the spectral changes with 10 ppm NH3, the intensity of the band at 1267 cm -1 decreasing with time Figure 7C is a plot of the integrated intensity of the band at 1267 cm-1 with respect to time, with 1 and 10 ppm of NH3 The increase in the intensity of the band at 1267 cm-1 is evident with 1 ppm NH3, but with 10 ppm, the increase in intensity is not so obvious, although the decrease in intensity of this band over time is more marked. Similar trends in resistance changes (Fig. 6A) and peak intensity at 1267 cm-1 (Fig. 7A) are discussed in more detail below.
Characteristics of detection
Carbon monoxide: All detection experiments were performed with 2 minute pulses of the gaseous analyte. FIGS. 8A and 8C show the behavior of the integrated Ni0 / In203 sensor (FIGS. 4A and 4B) with respect to CO pulses (10, 3, 1 ppm). Resistances across the three channels are presented, including ln203 (CH1, Fig. 8A), NiO (CH2, Fig. 8B), and the In203-NiO combination (CH3, Fig. 8C). With CO, ln203 shows a decrease in resistance (n-type behavior), and with NiO, an increase in resistance (p-type behavior). With the proper inclusion of both oxides, the change of resistance in the presence of CO is extremely reduced.
Nitric Oxide FIGS. 9A to 9C show the data obtained with 5 and 10 ppb of NO. Just as in the case of the CO response, NiO and ln203 give opposite responses (Figs. 9A and 9B), but since NO is an electron acceptor, the direction of resistance change is reversed, relative to at the CO. Nevertheless, when the two metal oxides are combined (CH3), the NO response is minimized (Figure 9C).
Ammonia: with a pulse of NH3 (1 ppm, 0.5 ppm, 0.1 ppm) of 2 minutes, as can be seen in Figures 10A and 10C, both ln203 and NiO show a decrease in resistance, and when both oxides are included, the signal remains large even at 100 ppb. Gas mixture: These experiments were then repeated with NH3 and CO in the gas stream with the gas pulses of 2 minutes. Figures 11A to 11C show the results. With In2C> 3, NH3 (0.1, 0.5, 1 ppm) results in a decrease in resistance (CH1, FIG. 11A). If CO (1, 3, 10 ppm) is included with the NH 3, the NH 3 signal is exceeded (CH 2, Figure 11B). A similar situation exists with NiO, except that an increase in resistance is observed if CO is included in the gas pulse. However, the signal from the NiO-In203 combination channel (CH3, FIG. 11C) only shows a signal for NH3, and the effect of CO, even at a concentration 100 times higher than that of NH3, is canceled. Human breath samples
Three series of experiments were performed with human breath samples, and are shown schematically in Figures 12A-12C.
Use of inhaled as background: breath samples were collected in bags of Mylar. These samples were independently mixed using mass flow controllers with 10, 50, 100, 500, 1000 ppb of NH3 and these samples were analyzed using the combined NiO-In203 (CH3) sensor. In these experiments, the background signal was that of the breath alone, followed by the introduction of NH 3 into the gas mixture. The first experiment included equilibration of the breath with water vapor at 37 ° C with a measured relative humidity of 93% (Figure 12A) and then the detection measurement. The second experiment included passing the breath through an ice bath to obtain 30% humidity (using the apparatus shown in Figure 12B). The third experiment included passing the breath through a moisture trap at a temperature of -20 to 25 ° C to obtain a resulting moisture of 0% (Figure 12B). The resulting detection data obtained using CH3 are shown in Figs. 13A-13D (Figs. 15-17 show data for all channels). With both wet samples (Figures 13A and 13B), the response to NH3 was poor. The presence of water influences the NH3 detection signal on both NiO and In2 <D3, particularly the first one (Figure 15), NiO showing an increase in resistance with NH3, and the opposite is observed with dry gas (FIG. 10A to 10C). With the breath sample mixed with NH3 (bpt - 33.7 ° C) passing through at -20 ° C, the expected signal for the added NH3 was obtained (Figure 13C). The calibration curve with the breath sample is shown in Figure 13D, and indicates saturation with increasing concentrations.
Use of air as background: In another series of experiments, air was used as the background atmosphere (Figure 12C), and a breath sample was measured using CH3 (all samples passing through through the dry ice trap at a temperature of -20 to -25 ° C). Figure 14A shows that breath alone provides a signal, but species at the origin of this signal can not be determined. However, an increase in signal is observed if the breath is mixed with NH 3, as can be seen in Figure 14A. Such a conventional add-on experience clearly indicates that the sensor detects NH3. The baseline breath signal was normalized to Ro / R = 1, and the signal increase (measured by Ro / R) due to the added NH3 is shown in Figure 14B.
Discussion
In order to demonstrate the practical application of the sensor described in this document, a human breath sample was used as a proof of principle sample. Detection of NH3 in human breath at levels of the order of ppb could be useful for diagnosing various diseases. Conventional levels of CO and NO in human breath are in the order of ppm and ppb, respectively. The result of this study is a sensor that is capable of detecting NH3 at low concentrations (<1000 ppb), with selectivity to CO at a rate of the order of ppm and NO at a rate of ppb order.
The sensor design employs a mixture containing p-type and n-type semiconductor oxides, but which are physically separated by a common interface (FIG. 3 and FIGS. 4A-4D). The separate oxides p and n make it easier to modify the contribution of each oxide to the resistance than a physical mixture of powders.
The two oxides examined here are n-type αη2θ3 and p-type NiO. The conduction model for n-type and p-type metal oxide gas sensors was reviewed. In both n and p oxides, oxygen ionosorption plays a crucial role in the detection model. In the case of the n-type, this chemisorption results in a decrease of the majority carrier electrons at the surface of the grains, whereas in the p-type oxides, the ionosorption of the oxygen results in an accumulation on the surface of holes. In n-type oxides, the conduction passes through the mass of the oxide, whereas with the p-type, the conduction passes along the surface. Under certain conditions, resistance changes from n-type to p-type and vice versa were observed. This effect is observed on Fe2O3, MoO3, In2C> 3, SnO2, TeC> 2 and TiO2, and several explanations have been proposed, in particular the formation of a surface inversion layer by means of a surface adsorption, the different types of surface reactions, the influence of polymorphs and morphology, as well as the effect of dopants / ionic impurities.
Resistance changes in NiO and Ιη203 on exposure to CO and NO were observed (Figures 8A and 8B and Figures 9A and 9B). NiO behaves like a p-type semiconductor, with hole conduction as the main contribution. CO reacts with chemisorbed oxygen on the oxide surface, releasing electrons, increasing the resistance of the P-type NiO and decreasing the resistance of the n-type In203. With the appropriate contributions from both oxides, the CO resistance change can be canceled (Figure 8C). Similar observations have been made with NO (Figure 9C).
Under conditions in which NH3 can react with chemisorbed oxygen, it usually behaves as a reducing gas, with the following proposed reactions: 2NH3 + 30 "- N2 + 3H20 + 3e (1) 2NH3 + 50" - 2N0 + 3H20 + 5th (2)
These reactions are further promoted at elevated temperature. Resistance changes in the interaction of NH3 with metal oxides may be irregular. For n-type oxides, such as ln203 and WO3, a decrease in resistance to low temperatures (<300 ° C) is observed. However, at higher temperatures, the initial decrease in strength is followed by an increase in resistance. For n-type semiconductors, NO, the product of the oxidation of NH3 during chemisorption results in an increase in resistance. This competition between NH3 oxidation and NO chemisorption is used to explain the irregular detection behavior. To avoid the uneven detection behavior due to NOx, low temperature operation or the use of catalysts has been suggested. Other explanations of the irregular behavior, as with the hexagonal W03, have been attributed to the formation of an inversion layer.
Our data obtained with Ιη2 <03 at 300 ° C indicate that NH3 behaves as a reducing gas (Figure 10A), with a decrease in resistance. The resistance changes with NH3 on the p-type NiO are more complicated. The increase in resistance observed at 500 ° C. with 1 ppm of NH3 (FIG. 6C) and 10 ppm of NH3 at 300 ° C. (FIG. 6D) can be explained by reactions (1) and (2), where the electrons created during the oxidation of NH3 combine with the majority carrier holes and lead to an increase in resistance, which is consistent with previous studies on NiO with 20 to 50 ppm of NH3. The behavior with 1 ppm of NH3 at 300 ° C is not the expected one and must be interpreted differently. As can be seen in Figure 6A, there is an initial decrease in resistance during the first minutes, followed by a gradual increase. Differences in resistance direction change as a function of analyte concentrations were observed. On p-type TeC> 2 at low temperature (80 ° C), the resistance decreases with ethanol (<300 ppm), an abnormal behavior, while with higher concentrations of ethanol, the resistance increases, as can be expected with a reducing gas on a p-type material. With p-type CuO nanowires, by taking NO2 as an oxidizing gas at a concentration <5 ppm, the resistance increases (abnormal behavior), whereas with 30 to 100 ppm NO2, the resistance decreases, as can be seen in FIG. wait with an oxidizing gas and a p-type material.
The in situ IR spectra shown in FIGS. 7A-7C provide some clues. Formation of a 1267 cm-1 band on NiO is observed when the gas changes from N2 to 20% C> 2 at 300 ° C (Figure 7A-7C). This band disappears if ΙΌ2 is replaced by N2, so that we assign this band to a chemisorbed species of oxygen. When introducing 1 ppm of NH3, an increase in the intensity of this band is observed, then a decrease. The change in intensity of the band at 1267 cm -1 in Fig. 7C in the presence of 1 ppm NH 3 reflects the change in conductivity upon exposure of NiO to 1 ppm NH 3 / as can be seen in Fig. 6A (times do not exactly overlap because IR was performed on a powder sample).
Several previous studies mention a band in the region ranging from 1200 to 1300 cm-1 during the chemisorption of oxygen on metal oxides. On Fe2O3, the bands between 1250 and 1350 cm-1 were assigned to disturbed O2 species and, in particular, the 1270 cm-1 band is prominent and stable up to 300 ° C. There are few infrared studies of oxygen adsorption on NiO, bands at 1070 and 1140 cm-1 being observed at 77 K and attributed to O2-. On Fe 2 O 3, bands in the range of 900 to 1100 cm -1 have been assigned to O22- type species. The formation of O "on NiO has been proposed, but no distinct infrared band has been identified.Peroxo species (O22") have been proposed during the adsorption of oxygen on NiO. On CuCl and CuBr, a band at about 1270 cm-1 was attributed to Cu + coordinated O2, and the intensity of this infrared band also decreased on exposure to NH3. On the basis of these studies, the band at 1267 cm-1 (FIGS. 7A, 7B) on NiO can be attributed to O2-.
The reactivity of NH3 on the surfaces of the metal oxides is enhanced in the presence of oxygen. On a surface of Mg (0001), NH3 reacts with the surface only in the presence of oxygen. The oxygen chemisorbed on Ni (110) and Ni (100) reacts with NH3 with H capture and formation of NHX type species. Surface spectroscopic studies have shown the high reactivity of NH3 with oxygen adsorbed on Ni (111).
It has been proposed that O2 "is in equilibrium with 0": 02 "* 5 0" + 0 (3)
The chemisorption of NH3 at low temperature can give NH2 and OH- through a reaction with 0 ":
Mx + ..... NH3 + 0 "- Mx + .... NH2 + 0H" (4) The adsorption of ammonia on an alumina surface (acid / base sites) can lead to the formation of NH2 and OH for about 10% of all the NH3 molecules that are absorbed. The bands due to NH2 have been reported at 3386 and 3355 cm-1. A dissociative chemisorption of NH3 in NH2 and OH carried out by oxygen functionality is observed on epoxide groups in a reduced graphene oxide, with vibration bands attributed to 3208, 327 0 cm-1 (NH2) and 3400 cm-1 ( OH) . With NH3 at 1 ppm on NiO, bands due to NH2 were observed, but with NH3 at 100 ppm on NiO at 300 ° C and then cooled to room temperature, a band appeared at 3220 cm-1 in the presence of '02, but not when N2 is only present (these spectra are shown in Figures 18A and 18B). The 3220 cm-1 band can be attributed to the lengthening of N-H.
Based on these observations, the uneven NH3 behavior at 1 ppm observed in Figure 6A can be explained. It is assumed that the reactions (3) and (4) take place on the surface of the NiO (we have evidence obtained by IR of the presence of species 02 "), and with (4) occurring, one can s' expect more chemisorption of 02 as 02 ~ as 0 "is consumed in reaction (4). IR indicates a transient increase in the 02 'band at NH3 exposure (Figure 7A). With the increase of the 02 chemisorption in the form of O 2, a decrease in resistance occurs. The increase in resistance observed later occurs due to subsequent reactions (1) and (2) due to the oxidation of NH3. At higher temperatures, or with higher concentrations of NH3, the transient decrease in resistance is not observed (Figures 6C, 6D) because reactions (1) and (2) are favored.
The transient decrease in resistance when exposed to low levels of NH3 on NiO was exploited to amplify the sensor signal. This was done by exposing the NiO for only 2 minutes to NH3, thus allowing time for the chemisorption effects to occur (reactions 3 and 4, Figure 6B), but without allowing time for the chemical reactions to occur (reactions 1 and 2) . The resistance of NiO decreases and then recovers fairly quickly, compared with the 10-minute exposure, where the products of the chemical reaction form and must be desorbed, before the sensor baseline is reached, and at 300 ° C, takes 40 minutes. With the 2-minute NH3 exposure, both NiO and In203 show a decrease in resistance, so that the detection data that combines the two oxides (CH3) result in an additive effect, by amplifying the response from NH3 ( FIGS. 10A-10C), whereas with NO and CO, the opposite response results in cancellation of the signal (FIGS. 8A-8C, 9A-9C). This strategy allows us to detect the presence of NH3 in the range of NH3 concentrations <1000 ppb, in the presence of CO, as can be seen in Figures 11A-11C.
Since the amount of NH3 to be detected in the human breath is of the order of a few hundred ppb, breath samples have been studied as samples that can be used with this sensor. The moisture in the breath creates significant interference (Figs. 13A, 13B), and the NH3 signal could be recovered (Fig. 13C) only when the water was removed from the breath by means of a cold trap (-20 ° C). Since both NH3 and H2O can act as Lewis's base, it is not surprising that moisture interferes with NH3. Moisture is not the only one to interfere with NH3 because other gases, such as CO, are capable of both n-type and p-type materials. The chemisorption of water may follow the same reaction as reaction (4), resulting in the formation of hydroxyl groups, with the formation of an Mx + - OH bond. The observation that the resistance of NiO increases in the presence of NH3 when water is present (Figures 15) indicates that the adsorption of water disrupts the chemisorption of oxygen in the form of O 2 ~, probably by adsorption at these sites. Therefore, the arrangement of p-n oxides can minimize interference from other gases, such as CO, but because of the pronounced interaction of water with oxides, in general, moisture will interfere immensely with nh3.
By removing moisture, the sensor can detect NH3 that is mixed in the breath. We performed the breath + NH3 experiments in two ways. Breath is used as the background sample, and any increase in NH3 in the breath can be measured (Figures 13C and 13D). Or the breath can be measured using air as a background sample, breath alone gives a signal and then any increase in NH3 can be measured from the signal increase (Figure 14A and 14B). A possible biomedical application of this sensor may be the measurement of an increase in NH3 in the breath. To diagnose H. pylori infection, the current standard of measurement involves administering to the patient a sample of 13C or 14C-labeled urea. Urease in the stomach (from bacteria) decomposes urea into 13CO2 or 14CO2 and NH3. The radioactivity of 14CO2 in the breath is then measured. With 13C02, a mass spectrometer is needed to perform the measurement. As the sensor described in this document can measure NH3 at ppb levels, the diagnosis of H. pylori infection could be potentially simplified by administering to the patient normal (unmarked) urea and measuring the released NH3. The moisture trap to remove water would still be needed. The trap can eliminate other volatile organics in the breath, but this is not a problem in the application we propose for this sensor. Gases such as CO and NO (with NH3) may still pass through the trap, and the p-n strategy described herein minimizes the influence of these disturbing substances while enhancing the NH3 signal.
Conclusion
This example shows the use of p-type N and n-type ln203 placed side by side on a substrate with a common interface as the detection platform. Adjacent placement of the oxides facilitates the change in the amount of oxide to be included in making the resistance measurements in the presence of a gaseous analyte. With this strategy, the change in resistance with 3 to 10 ppm CO is practically zero, since ln203 and NiO give opposite responses to CO. Ammonia is also a reducing gas, but at low concentrations of NH3 (<1 ppm) at 300 ° C, the response with ln203 is a decrease in resistance, but with NiO the change in resistance is uneven. During the first 8 minutes of a 10 minute exposure to NH3, a decrease in resistance is observed, then a progressive increase in resistance during the next 20 minutes, then a decrease for 10 minutes to the base resistance. Using infrared in situ spectroscopy, this behavior has been correlated with the chemisorption of NH3 and the involvement of the 02 species. The transient reduction with NH3 on NiO was taken advantage of to design a sensor showing a decrease in resistance for both NiO and In203 by fixing the gas pulses at a duration of 2 minutes. With this strategy, the combination of the two oxides improves the NH3 signal, allowing detection at a concentration of 100 ppb. These sensors were used to detect NH3 mixed with human breath. By completely removing moisture from the breath sample, 10 to 1000 ppb of added ammonia can be detected. Water interference occurs because of competition reactions with O 2 ~ and the transient decrease in NH 3 resistance on NiO is no longer observed at all, eliminating amplification. A potential application of such a detector could be in the diagnosis of H. pylori.
The devices, systems and methods of the appended claims are not limited in scope by the specific devices, systems and methods described herein, which are intended to illustrate some aspects of the claims. Any device, system and method that is functionally equivalent is intended to fall within the scope of the claims. The various modifications of the devices, systems and methods in addition to those presented are described herein and are intended to fall within the scope of the appended claims. Furthermore, although only certain representative devices, representative systems and process steps disclosed herein are specifically described, the other combinations of devices, systems and process steps are also intended to be within the scope of the present invention. appended claims, even if not specifically mentioned. Therefore, a combination of steps, elements, components, or constituents may be explicitly mentioned herein, however other combinations of steps, elements, components, and constituents are included even if they are not explicitly indicated.
The term "comprising" and its variations, as used herein, is used synonymously with the term "including" and its variations and are non-limiting open terms. Although the terms "comprising" and "including" are used throughout this document to describe various embodiments, the terms "consisting essentially of" and "consisting of" may be used in place of the term "comprising" and the term "Including" to provide more specific embodiments of the invention and are also disclosed. Unless otherwise indicated, all numbers expressing geometries, dimensions, and so forth used in the specification and claims shall be understood as a minimum, and not as an attempt to limit the application of the doctrine of equivalents to the scope of claims, to be interpreted in light of the number of significant digits and ordinary rounding approaches.
Unless defined otherwise, all technical and scientific terms used herein have the same meanings as those conventionally understood by those skilled in the art to which the disclosed invention belongs.

权利要求:
Claims (17)
[1" id="c-fr-0001]
A detection device for detecting NH3 in a gas sample, the detection device comprising a detection element comprising: a first region comprising a p-type metal / oxide / semiconductor material (MOS) comprising NiO ; and a second region comprising n-type MOS material comprising 1'Ιη2θ3; wherein the first region is adjacent to and in contact with the second region.
[2" id="c-fr-0002]
The detection device according to claim 1, wherein the p-type MOS material is NiO, wherein the n-type MOS material is In2O3, or wherein the p-type MOS material is NiO and the n-type MOS material consists of Ιη2θ3.
[3" id="c-fr-0003]
The sensing device of any one of claims 1 to 2, wherein the sensing device further comprises: a first electrode established within the first region; a second electrode established within the second region; a wiring interconnecting the first and the second electrode; and optionally a platform assembly holding the first and second electrode in an array of electrode wires selectively in contact with the sensing element; wherein a resistance measured along the wiring indicates the presence of NH3 in a gas interfacing with the sensing element.
[4" id="c-fr-0004]
The detection device according to claim 3, wherein the platform assembly is adapted to selectively change a contact location of the first electrode within the first region and selectively modify a contact location of the second electrode at the first electrode. within the second region, optionally wherein the platform assembly is adapted to selectively change a distance between the first electrode and the second electrode.
[5" id="c-fr-0005]
The sensing device according to any one of claims 3 to 4, wherein a location of the first electrode with respect to the first region and a location of the second electrode with respect to the second region is selected so that the measured resistance is not affected by the presence of CO, NO or a combination thereof in a gaseous sample interfaced with the sensing element.
[6" id="c-fr-0006]
The detection device according to any one of claims 3 to 5, wherein the sensing element defines a length from a first side to a second opposite side, the first side being defined by an edge of the first region opposite to the second region, the second side being defined by an edge of the second region opposite the first region, and wherein a location of the first electrode relative to the first region and a location of the second electrode relative to the second region. are selected such that the cabling includes a combined amount of p-type MOS material and n-type MOS material in the length direction that is predetermined to generate a measured resistance indicating the presence of NH3 in a gaseous sample interfaced with the detection element.
[7" id="c-fr-0007]
The detection device according to claim 6, wherein the predetermined combined amount is selected so that the measured resistance is not affected by the presence of CO, NO or a combination thereof in the gaseous sample. in interface with the detection element.
[8" id="c-fr-0008]
The sensing device of any one of claims 1 to 7, further comprising: a third electrode established within the first region at a location separate from that of the first electrode; a fourth electrode established within the second region at a location separate from that of the second electrode; and wiring interconnecting the third and fourth electrodes; wherein a resistance measured along the wiring interconnecting the third and fourth electrodes in comparison with the resistance measured along the wiring interconnecting the first and second electrodes indicates a concentration of NH3 in a gas interfacing with the sensing element.
[9" id="c-fr-0009]
A detection system for detecting NH3 in a gaseous sample, the system comprising a detection device comprising: a sensing element which comprises: a first region comprising a p-type MOS material comprising NiO; and a second region comprising n-type MOS material comprising 1n203; wherein the first region is adjacent to and in contact with the second region, a first electrode established within the first region; a second electrode established within the second region; and a database correlating the measured resistance along the wiring between the first electrode and the second electrode with the presence of NH3 in a gaseous sample interfaced with the sensing element.
[10" id="c-fr-0010]
The system of claim 9, further comprising a controller holding the database and electronically associated with the cabling, wherein the controller comprises a memory on which is stored: the database; instructions for receiving a plurality of measured resistance values generated by the detection device in the presence of the gas sample; and instructions for estimating an NH3 concentration in the gas sample based on the plurality of measured resistances.
[11" id="c-fr-0011]
A method of detecting NH3 in a gaseous sample, the method comprising providing a detection system comprising: a sensing element which comprises: a first region comprising a p-type MOS material; and a second region comprising n-type MOS material; wherein the first region is adjacent to and in contact with the second region, a first electrode established within the first region; a second electrode established within the second region; and a database correlating the resistance measured along the wiring between the first electrode and the second electrode with the presence of NH3 in a gaseous sample interfacing with the sensing element contacting the sensing element of the detection system with the gaseous sample, measuring a resistance along the wiring between the first electrode and the second electrode, and detecting NH3 in the gaseous sample based on the measured resistance.
[12" id="c-fr-0012]
The method of claim 11, wherein the p-type MOS material comprises NiO, CuO, CO 3 O 4, Cr 2 O 3, Mn 3 O 4 or a combination thereof, and wherein the n-type MOS material comprises In203, SnC2, T1O2, WO3, ZnO, Fe2O3 or a combination thereof.
[13" id="c-fr-0013]
The method of any one of claims 11 to 12, wherein the detection of NH3 in the gaseous sample comprises estimating an NH3 concentration in the gaseous sample based on the measured resistance.
[14" id="c-fr-0014]
The method of any one of claims 11 to 13, wherein contacting the sensing element with the gaseous sample comprises exposing the sensing element to a gaseous sample for 30 seconds at five. minutes, for example for 1 to 3 minutes.
[15" id="c-fr-0015]
The method of any one of claims 11 to 14, further comprising heating the sensing element to a temperature of 250 ° C to 450 ° C.
[16" id="c-fr-0016]
The process of any one of claims 11 to 15, wherein the NH 3 concentration in the gaseous sample is less than or equal to 5,000 ppb, for example, 50 ppb to 2,000 ppb.
[17" id="c-fr-0017]
A detection system for detecting NH3 in a breath sample collected from a patient, the system comprising a sensing device comprising: a sensing element which comprises: a first region comprising a p-type MOS material; and a second region comprising n-type MOS material; wherein the first region is adjacent to and in contact with the second region, a first electrode established within the first region; a second electrode established within the second region; a mouthpiece adapted to collect the breath sample from the patient and bring it into contact with the sensing element; a database correlating the resistance measured along the wiring between the first electrode and the second electrode with the presence of NH3 in a gaseous sample interfaced with the sensing element; a controller holding the database and associated electronically with the cabling, wherein the controller comprises a memory on which are stored: the database; instructions for receiving a plurality of measured resistance values generated by the detection device in the presence of the breath sample; instructions for estimating a concentration of NH3 in the breath sample based on the plurality of measured resistances; and instructions for assigning a score for progression of H. pylori infection in the patient based on the estimated NH3 concentration in the breath sample.

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同族专利:

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公开号 | 公开日

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KR20180088674A|2018-08-06|

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US20210148877A1|2021-05-20|

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JP2018536168A|2018-12-06|

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CN106814109A|2017-06-09|

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GB2545038A|2017-06-07|

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GB201608769D0|2016-06-29|

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DE202016003205U1|2016-11-02|

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法律状态:
2017-05-25| PLFP| Fee payment|Year of fee payment: 2 |

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2018-05-25| PLFP| Fee payment|Year of fee payment: 3 |

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2018-12-07| PLSC| Search report ready|Effective date: 20181207 |

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2020-04-24| RX| Complete rejection|Effective date: 20200319 |

优先权:

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申请号 | 申请日 | 专利标题

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US201562262067P| true| 2015-12-02|2015-12-02|

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