• 专利附录
  • 专利说明
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    • 专利摘要:
    Humidity sensor. The present invention provides a humidity sensor for the detection of accumulated moisture by electronic and optical reading, comprising a solid support and a sheet of zinc nitride with a thickness comprised between 10 nm and 100 μm, where the sheet of Zinc nitride is disposed on the solid support. Also, the invention provides a method for the preparation of the humidity sensor of the invention. The sensor of the invention can be used for the detection of moisture in food, electronic products, drugs, armaments, building elements and works of art. As well as for the detection of perspiration in animals and plants. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2657123A1
    申请号:ES201631059
    申请日:2016-08-01
    公开日:2018-03-01
    发明作者:José Luis PAU VIZCAÍNO；Andrés REDONDO CUBERO；María Teresa GÓMEZ CASTAÑO
    申请人:Universidad Autonoma de Madrid；
    IPC主号:
    专利说明:

    DESCRIPTION Humidity sensorFIELD OF THE INVENTION
    The present invention relates to humidity sensors for the detection of accumulated humidity by electronic and optical reading. 5
    BACKGROUND OF THE INVENTION
    The quality of certain commercial goods and products is degraded by moisture until they are not suitable for consumption or use, or deteriorate irreversibly. An example is certain semiconductor components that need to be encapsulated at relative humidity (RH) levels below 5% to avoid degradation during storage and / or transport. Many manufacturers of electronic devices such as mobile phones and laptops incorporate sensors in the devices themselves that allow to record the humidity levels to which it has been exposed during use, affecting its reading to the warranty coverage. On the other hand, 15 many electronic products need to be maintained at humidity levels below 40% to prevent corrosion of metal components that are the cause of breakdown and deterioration.

    Moisture is also a key factor in food degradation due to the need for water that microorganisms have to dissolve food. The water favors that the components of the foods penetrate in the cells of the bacteria, accelerating their deterioration. In addition, it allows chemical reactions to occur between the components of the product resulting in the change of morphology or the formation of agglomerates, as in the case of grains, cereals, seeds or flours. 25

    The stability of works of art also depends largely on the degree of humidity to which they are exposed. Its effects can be made visible through the appearance of cracks, wrinkles, deformations, or loss of color. Consequently, it is important to maintain a strict control of the dose of moisture that these goods receive during their transport or storage.

    In environments with moderate relative humidity (<40%) and temperature of about 20ºC, water molecules can adsorb on the surface of the materials forming several
    monolayers of water on the surface. For some time, there have been commercial cards based on cobalt chloride (CoCl2) that allow quantifying the relative humidity in watertight containers by changing the color from blue for low RH levels to pink for high levels. The behavior is reversible and they are used to indicate the level of humidity at the moment in which the check is made. These 5 cards can be purchased in various formats and are commonly used in the semiconductor industry and in military applications. In 1998, the European Union launched a directive that included cobalt chloride as a toxic substance with risk code R49 (possible cause of cancer if inhaled). Since then many companies have developed moisture indicator cards, free of cobalt chloride. One of the 10 most used alternative materials is copper chloride, whose use in the development of moisture devices was revealed through US Patent 2460072 A in the 1940s. Other compounds with patents published at the same time are bromide of cobalt, cobalt phosphate or cobalt sulfate, through patents US 2460068 A, US 2460070 A and US 2460066 A. 15

    All these materials allow a reading of the degree of humidity by direct visualization of color. However, due to the strong ionic character of these salts, the electrical conductivity they present in the solid state is low, preventing the realization of electrical readings. In addition, certain electronic products can be damaged by exposure to high humidity levels for short periods of time, so it is necessary to integrate sensors that record changes if levels are reached higher than those allowed in short time intervals. For this purpose, various irreversible moisture indicators have been patented based on the combination of deliquescent salts with water soluble inks. Examples of such devices can be found in patents US 2214354 A, US 4793180 A, US 6698378 B1 and US2008 / 0163673 A1. Exposed to high levels of humidity, the salts liquefy and release the ink through a porous material, leaving a permanent mark on the surface. One of the problems posed by this solution is that, when it enters the liquid state, the salts can cause corrosion of the products stored in the container 30 or container. In addition, the porous material used is usually blotting paper which can cause contamination with fibers or fluff of the products they try to preserve.
    Currently, agents involved in the transport of goods require the inclusion of devices that allow remote monitoring of environmental conservation parameters during transit. An example of these devices are radio frequency identification tags (RFID tags). These tags allow you to register data
    of resistive sensors connected to them and supply the information to an external reader through radio frequency signals. An example of the use of this technology can be found in US 6806808 B1.

    Therefore, in spite of the effort used in the development of humidity sensors in the last 5 times, there is still a need in the state of the art of humidity sensors that allow the electronic detection of the accumulated humidity to eliminate the need to maintain a direct eye contact, and that can work for long periods of time in conditions of high humidity. OBJECT OF THE INVENTION 10
    The present invention provides a new type of humidity sensor that allows quantifying the dose of moisture received over time by electronic and optical reading (direct visualization), unlike the sensors known in the state of the art where the detection of humidity is at the same moment and the reading is only optical. fifteen

    Also, the humidity sensor of the invention has other additional advantages such as being low cost; do not produce contaminants since the materials used are solid and do not produce contaminants in the form of particles or fibers that can escape from the device; and the ability to be implemented in rigid and flexible substrates. In addition, the humidity sensor of the invention can be designed in advance to present the required lifetime.

    The humidity sensor of the invention is based on the use of a zinc nitride sheet that undergoes a color change, as well as a change in conductivity when transformed into zinc oxide. Thus, the authors of the present invention have observed that relative humidity plays an important role in the transformation of this compound, obtaining a reproducible correlation between the transformation time of the sheet and the relative humidity to which it has been exposed.
    Therefore, in a first aspect the present invention is directed to a humidity sensor 30 for the detection of accumulated moisture by electronic and optical reading, which comprises a solid support and a sheet of zinc nitride with a thickness between 10 nm and 100 µm, where the zinc nitride sheet is disposed on the solid support.

    In a second aspect the invention is directed to a manufacturing method of the humidity sensor comprising:
    a) provide a solid support, and
    b) deposit a sheet of zinc nitride with a thickness between 10 5 nm and 100 µm on the solid support of step a) at pressures between 10-1 and 10-8 mbar.
    The invention is also directed to the use of the humidity sensor for the detection of moisture in foods, electronic products, drugs, weapons, construction elements and works of art, as well as for the detection of perspiration in humans, animals or 10 plants. , and the detection of exhaled water vapors

    FIGURES
    FIGURE 1 shows a schematic of a sensor as defined in the present invention comprising a sheet of zinc nitride (1) disposed on a substrate (2), and 15 contacts of a metallic material (3) arranged on the sheet of zinc nitride

    FIGURE 2 shows the transmittance changes in the visible range of the electromagnetic spectrum of a humidity sensor as defined in the present invention comprising a sheet of zinc nitride of a thickness of 200 nm under conditions of relative humidity of 25% and 40% at 20 ° C.

    FIGURE 3 shows the resistivity changes experienced in a humidity sensor as defined in the present invention with a zinc nitride layer thickness of 200 nm as a function of time, for the following storage conditions: (1) relative humidity of 25% and temperature of 20 ° C, (2) relative humidity of 40% and temperature of 20 ° C, and (3) relative humidity of 25% and temperature of 50 ° C.

    FIGURE 4 depicts the resistivity as a function of time of sensors as defined in the present invention which have zinc nitride layer thicknesses from 25-30 nm to 530 nm under a relative humidity of 25% and at a temperature of 20 ° C.

    FIGURE 5 shows the voltage drop in a sensor as defined in the present invention with a zinc nitride layer thickness of 420 nm during a 23-minute aerobic exercise session and at rest for a period of 1 hour. 35

    FIGURE 6 shows the variation in resistance normalized over time and at different relative humidities of a sensor such as the one defined in the present invention with a zinc nitride layer thickness of 200 nm.
     5
    FIGURE 7 shows the psi (Figure 7a) and delta (Figure 7b) ellipsometric parameters in a sensor as defined in the present invention with a 630 nm zinc nitride layer thickness, freshly grown (virgin) and after exposure to different relative humidities.
     10
    DETAILED DESCRIPTION OF THE INVENTION
    The invention provides a humidity sensor for the detection of moisture accumulated by electronic and optical reading, comprising a solid support and a sheet of zinc nitride with a thickness between 10 nm and 100 µm, where the sheet of zinc nitride It is arranged on the solid support. fifteen

    In the context of the present invention, "humidity sensor" means a device capable of detecting a change in humidity in the surrounding environment. In particular, the humidity sensor of the invention is capable of detecting the accumulated moisture dose by electronic and optical reading. twenty

    In the context of the present invention, the term "moisture" refers to the amount of water vapor present in the medium. In particular, the humidity of the air is due to the water vapor that is in the atmosphere. In addition, the amount of water vapor that can be absorbed by the air depends on its temperature, with hot air admitting more water vapor than cold air.

    In particular, the term "relative humidity" or "HR" refers to the ratio of water vapor contained in any volume of air, relative to the water vapor necessary to saturate said volume, expressed as a percentage. The relative humidity can be calculated from the ratio between the molar fraction of water vapor in the air and the molar fraction of water vapor in saturated air at the same temperature, as shown in the following equation:
       HR = 100 * (n v / n vs)
     35
    nv = number of moles of water vapor in the air
    n vs = number of moles of water vapor in saturated air
    By admitting an air behavior as an ideal gas, the ideal gas equation can be applied: p * V = n * R * T
    The relative humidity can also be defined as the percentage of 5 vapor pressure that the air has with respect to the maximum it can have at that temperature, also called saturation humidity. HR = 100 * (p v / p vs)

    p v = vapor pressure in the air
    p vs = maximum water vapor pressure that the air can have at that temperature, or 10 saturation pressure.

    The term "absolute humidity" refers to the concentration of water vapor in the air, which corresponds to the relationship between the mass of water vapor and the volume occupied by the wet air mixture. fifteen

    In particular, in the context of the present invention the term "accumulated humidity" refers to the total humidity to which the sensor of the invention has been exposed before reading.
     twenty
    Unlike the sensors known in the state of the art, the sensor of the invention is capable of detecting the accumulated humidity, that is to say the total humidity to which the sensor of the invention has been exposed before reading.

    The sensor of the invention comprises a solid support on which a sheet of zinc nitride 25 is arranged. In the context of the present invention, "solid support" means a solid material that serves as a platform on which to deposit the zinc nitride layer. In a particular embodiment, the solid support can be rigid or flexible. Figure 1 shows a schematic representation of a humidity sensor of the invention where a layer of zinc nitride (1) is arranged on a solid support (2). 30

    The solid support of the sensor of the invention does not produce contaminants in the form of particles or fibers that can escape from the device. In a particular embodiment, the solid support is selected from glass, quartz, sapphire, silicon, gallium nitride, zinc oxide,
    Copper, aluminum and brass. In another particular embodiment, the solid support of the sensor of the invention is a thermoplastic polymer, preferably of polyethylene (PE), polypropylene (PP), polybutylene (PB), polystyrene (PS), polymethylmethacrylate (PMMA), polyvinyl chloride (PVC) ), polyethylene terephthalate (or ethylene polyterephthalate (PET)), Teflon (or polytetrafluoroethylene, PTFE), polyester, methacrylate, polyamide and polycarbonate. More preferably, the solid support is polyethylene, polyamide or polycarbonate terephthalate.

    The humidity sensor of the present invention comprises a solid support and a zinc nitride sheet (Zn3N2), where the zinc nitride sheet has a thickness between 10 nm and 100 µm and is disposed on the solid support. In a particular embodiment, the thickness of the zinc nitride layer is between 15 nm and 75 µm, preferably between 20 nm and 50 µm, more preferably between 30 nm and 10 µm, and even more preferably between 50 nm and 1 µm. In a particular embodiment, the thickness of the zinc nitride layer is between 75 nm and 700 nm, preferably between 100 nm and 630 nm, preferably between 150 and 600 nm, more preferably between 200 and 500 nm, even more preferably between 300 and 400 nm.

    In the presence of moisture, the adsorption of water vapor on the surface of the zinc nitride sheet of the sensor of the invention results in the transformation of zinc nitride into zinc oxide. Zinc nitride has a high conductivity, is opaque and brown-black in color, while zinc oxide is electrical insulating and with a high degree of transparency. Therefore, during the transformation of zinc nitride into zinc oxide, not only does a change in color appearance take place, but also a change in the electrical properties of the sensor. In addition, the process is cumulative, so that the transformation detected is the result of the level of humidity to which the device has been exposed throughout the storage period.

    The visual reading of the device provides information on the dose of moisture received through the transformation of zinc nitride, opaque brown-black material, to zinc oxide, highly transparent material. The change in color allows the establishment of an informative color scale directly related to the dose of moisture received. Figure 2 shows the transmittance changes in the visible range of the electromagnetic spectrum for 25% and 40% relative humidity of a humidity sensor of the invention with a zinc nitride layer thickness of 200 nm, measured using a halogen lamp as a light source with a broad spectral band and a CCD camera. 35 As shown in the figure, for 25% relative humidity, the transmittance reaches the
    100% at 9 days of storage, indicating that the transformation of zinc nitride into zinc oxide has occurred at 9 days. On the other hand, by increasing the relative humidity percentage to 40%, the change in transmittance is detected after two days of storage, as shown in the graph on the right of Figure 2.
     5
    When the sensor reading is only visual, transparent supports such as the thermostable polymers mentioned above are preferred. The transparent supports facilitate the visual reading of the sensor since they allow to detect the change of color in the transformation of the sheet of zinc nitride to zinc oxide. The final color of the sensor of the invention will depend on the substrate used. 10

    During the color change, the humidity sensor of the invention undergoes a remarkable resistance change due to the high conductivity of the zinc nitride and the low conductivity of the zinc oxide formed after the reaction. The conductivities of both materials differ by more than 6 orders of magnitude from 0.1-1.0 Ω cm, for 15 zinc nitride, up to 1x106 Ω cm, for zinc oxide, ensuring effective electronic discrimination in case of exceeding the maximum dose of moisture received.

    In a particular embodiment, when the sensor reading is only electronic, and not visual, the solid supports employed can be transparent solid supports such as the aforementioned; opaque plastic materials; semiconductor substrates, or metal substrates. Preferably, the semiconductor substrates are selected from silicon, silicon oxide, gallium nitride and zinc oxide, although many other alternative semiconductors of families IV, III-V and II-VI could be used, such as germanium, silicon carbide , gallium arsenide, indium arsenide, gallium antimonide, aluminum nitride, indium nitride, indium phosphide, cadmium telluride, zinc sulphide, cadmium selenide, and ternary or quaternary compounds generated by combination thereof or by doping with impurities. Preferably, the metal substrates are selected from copper, aluminum and brass, although they can be made of gold, silver, platinum, titanium, nickel, tin, indium, chromium, tungsten, and combinations thereof. 30

    For electronic reading, the sensor of the invention is electrically connected to a voltage detector capable of detecting the voltage drop in the sheet during the transformation of zinc nitride to zinc oxide. In a particular embodiment the sensor of the invention comprises a voltage detector, where the zinc nitride sheet is electrically connected to the voltage detector. Preferably, the sensor of the invention
    It is electrically connected to the direct contact voltage detector.

    The voltage detector electrically connected to the sensor of the invention can be a voltage divider capable of detecting the current drop or a radio frequency or RFID identification reader. Thus, a preferred embodiment of the present invention relates to the humidity sensor of the invention, where the zinc nitride sheet is electrically connected to a voltage divider or a radio frequency or RFID identification reader. Preferably, the zinc nitride sheet is electrically connected to a voltage divider or a radiofrequency or RFID identification reader through the contacts disposed on the zinc nitride sheet. 10

    In the context of the present invention, the term "radiofrequency identification reader" or "RFID" refers to an identification device capable of receiving electromagnetic or electrostatic waves for the transmission of the signal containing the information. Radio frequency identification readers are widely known in the state of the art. In general, an RFID system comprises at least the following components:
    - RFID tag: composed of a radio transducer, a chip that stores the information, and an antenna that transmits the information stored in the sensor chip, 20
    - RFID reader: composed of an antenna, a transceiver and a decoder. The reader periodically sends signals to see if there are any labels in its vicinity. When it picks up a signal from a tag, it extracts the information and passes it to the data processing subsystem.
    - Data processing subsystem or RFID Middleware: provides the means for data processing and storage.

    In a particular embodiment, the humidity sensor further comprises two insulated contacts of metallic materials disposed on the zinc nitride sheet. The two metal contacts allow connection to radio frequency devices for remote sensor reading. In a preferred embodiment, the metallic material of the insulated contacts is selected from aluminum, gold, silver, platinum, titanium, nickel, tin, indium, chromium, tungsten, copper and combinations thereof.

    In a particular embodiment, the zinc nitride sheet is electrically connected to the voltage detector through the contacts arranged on the zinc nitride sheet, in the humidity sensor of the invention.

    In another particular embodiment, the voltage detector electrically connected to the humidity sensor is further electrically connected to a Bluetooth technology emitting device for wireless communication with an external receiver.

    In a particular embodiment, when the humidity conditions are constant (constant RH), the increase in the thickness of the zinc oxide in depth is linear with the exposure time and follows a law of the type:

     In a particular embodiment, the zinc nitride sheet is electrically connected to the voltage detector through the contacts arranged on the zinc nitride sheet, in the humidity sensor of the invention.
    where k is a function that depends on relative humidity and temperature, and is time. In a particular embodiment, the zinc nitride sheet is electrically connected to the voltage detector through the contacts arranged on the zinc nitride sheet, in the humidity sensor of the invention. In a particular embodiment, the zinc nitride sheet is electrically connected to the voltage detector through the contacts arranged on the zinc nitride sheet, in the humidity sensor of the invention. In a particular embodiment, the zinc nitride sheet is electrically connected to the voltage detector through the contacts arranged on the zinc nitride sheet, in the humidity sensor of the invention.

    On the other hand, the authors of the present invention have observed that the relative humidity is the one that mainly produces the transformation of zinc nitride into zinc oxide obtaining a reproducible correlation between the transformation time of the sheet and the relative humidity at which It has been exposed. Thus, as the relative humidity increases, the rate of transformation of zinc nitride into zinc oxide is faster. Figure 3 shows the change in resistivity experienced for a sensor with a 200 nm thick zinc nitride layer under different temperature and humidity conditions. In particular, the figure shows that for a constant temperature of 20 ° C, the increase in humidity reduces the lifetime of the sensor, while for a constant humidity, the increase in temperature increases the lifetime of the sensor since it is limited and prevents adsorption of water molecules on the sensor surface.

    As an example, the life time (T.d.V.) of a 200 nm thick sheet is shown below, depending on the percentage of relative humidity (RH) under normal pressure and temperature conditions (25 ° C, 1 bar):
     RH (%)  0-50 70 80 90 100
     T.d.V. (day)  > 12 5 2 1 <1

    As shown in the table, as the degree of relative humidity increases, the lifetime of the sensor decreases, because the transformation of the zinc nitride sheet of the sensor of the invention to zinc oxide occurs in less time.

    Also, the thickness of the zinc nitride layer will determine the lifetime (T.d.V.) of the sensor in a humid environment. Figure 4 represents the variation of the resistivity as a function of time for sensors of the invention having thicknesses of the zinc nitride layer between 25 nm and 530 nm. The figure shows how the sensor's lifetime increases when the thickness of the zinc nitride layer is greater. Thus, in conditions of constant humidity, it is possible to program the thickness of the zinc nitride layer 10 necessary for the required lifetime. For example, from the data in the table included above, it could be estimated that a 400 nm thick sheet would have a lifespan of about 10 days at a 70% RH. In addition, this characteristic of the sensor of the invention allows the maximum quantifiable dose to be adjusted by the device and adapted to that allowed by the items included in a container or container. The operating ranges of these sheets can be established from a few hours to weeks or months. This degree of flexibility allows its use in a wide variety of products that can present different life times in high humidity environments.

    Procedure 20
    A further aspect of the invention relates to the manufacturing method of the humidity sensor of the invention, which comprises:
    a) provide a solid support, and
    b) deposit a sheet of zinc nitride with a thickness between 10 nm and 100 µm on the solid support of step a) at pressures between 10-1 and 10-8 mbar.
    A solid support is provided in step a) of the process of the invention. In the context of the present invention, the solid support serves as a platform on which the zinc nitride sheet of the sensor of the invention is deposited. Preferably, the solid support is selected from glass, quartz, sapphire, polyethylene terephthalate, polyamide, polycarbonate, silicon, gallium nitride, zinc oxide, copper, aluminum and brass.
    In step b) of the process of the invention, a sheet of zinc nitride with a thickness between 10 nm and 100 µm is deposited on the solid support provided in step a) at pressures between 10-1 and 10-8 mbar . Preferably, the sheet
    of zinc nitride is deposited at pressures between 10-2 and 10-6 mbar, more preferably at pressures between 10-3 and 10-5 mbar.
    In a particular embodiment, the zinc nitride sheet with a thickness between 10 nm and 100 µm is deposited on the solid support in step b) by sputtering in alternating current (RF) or by pulsed direct current in the presence of a 5 nitrogen plasma and noble gases. Among the noble gases that can be used for the deposition of the zinc nitride sheet, Ar is preferred.
    In a preferred embodiment, the zinc nitride layer is deposited at room temperature under high vacuum conditions by sputtering on a solid support.
     10
    Sputtering employs a radiofrequency source to generate a plasma from N2 gas. The ionic species of the plasma are accelerated towards a cathode of zinc, installed in the high vacuum chamber, with which they collide producing the emission of atoms from the surface of the target by elastic impact. Thanks to the energy acquired in the impact, the atoms torn from the cathode reach the substrate by depositing on it. In that path, the zinc atoms react with the ionic species of the N2 plasma resulting in the formation of a thin sheet of Zn3N2. The thickness of this sheet is linearly dependent on the exposure time of the substrate to the flow of cathodic particles. The rate of deposit depends on parameters such as the power applied to the cathode or the working pressure. The experimental conditions necessary to achieve the zinc nitride sheet of the sensor of the invention, with a thickness between 10 nm and 100 µm, are known to those skilled in the art. In particular, for a power 100 W and a pressure of 10-2 mbar that range is equivalent to deposit times between 15 seconds and 40 hours.
    The humidity sensor manufactured following this procedure can have any shape or size, only limited by the geometry of the zinc nitride cathode used in the sputtering system.

    In a particular embodiment, the process of the invention further comprises a stage after step b) where two insulated contacts of metallic materials 30 are deposited on the zinc nitride sheet of step b). In a particular embodiment, the metallic material of the insulated contacts is selected from aluminum, gold, silver, platinum, titanium, nickel, tin, indium, chromium, tungsten, copper and combinations thereof.

    In another particular embodiment, the two insulated contacts of metallic materials are deposited on the zinc nitride sheet of step b) by sputtering at pressures between 10-1 and 10-8 mbar using a mechanical mask. Preferably the sputtering is performed at a pressure between 10-2 and 10-6 mbar, more preferably between 10-3 and 10-5 mbar. 5

    In the context of the present invention, the term "mechanical mask" refers to a template that has at least two perforated areas, so that when arranged on the material to be coated, it allows the coating to be made only in the isolated regions of the surface of the material to be coated that is exposed, that is, those that are found just below the perforated areas of the template. The mechanical mask allows the manufacture of the insulated contacts on the surface of the zinc nitride sheet. The mechanical mask can be made from aluminum, copper, titanium, zinc or nickel metals, alloys such as steel, stainless steel or brass, and plastic materials. fifteen

    In the humidity sensor of the invention comprising the two insulated contacts on the surface of the zinc nitride layer, the electrical connection to the voltage detector can occur through said contacts.
     twenty
    Industrial application
    The humidity sensor of the invention, due to its ability to transform from an opaque material, black brown, and electrically conductive to a material with a high degree of transparency and electrical insulation, can be used for the detection of moisture in food, electronic products, drugs, weapons, construction elements and works of art. In particular, the humidity sensor of the invention can be placed in any container or container, keeping it close to the object to be preserved and out of direct contact with liquid substances. Thus, when a humidity exposure level higher than that allowed by the specifications of the product to be preserved is reached, the electrical resistance of the sensor of the invention increases by several orders of magnitude 30 due to the transformation of zinc nitride to zinc oxide . Therefore, in a particular embodiment the invention relates to the use of the humidity sensor of the invention for the detection of moisture in food, electronic products, drugs, weapons, construction elements and works of art.
     35
    Another particular embodiment relates to the use of the humidity sensor of the invention for the detection of perspiration in humans, animals or plants. Figure 5 shows the significant voltage drop in the sensor during an aerobic exercise session compared to the voltage signal stability during a nap period.
     5
    Also, another embodiment relates to the use of a humidity sensor for the detection of exhaled water vapors.

    The invention will now be illustrated by examples, which should not be construed as limiting the invention, which is defined by the claims. 10

    EXAMPLES:
    EXAMPLE 1
    Deposit of zinc nitride layer
    A sensor belonging to the invention was manufactured from a sheet of zinc nitride deposited by sputtering with radio frequency magnetron in reactive mode. For this, a glass substrate was loaded into the system introduction chamber and transferred under high vacuum conditions to the main chamber. The base system pressure was 10-5 mbar. In the main chamber, the substrate was placed facing a white Zn of 4 inches in diameter and 1/4 inch thick with a purity of 99.995%. After introducing a flow of nitrogen of 30 sccm (99.999% purity) into the main chamber and reaching a working pressure of 10-2 mbar, a plasma was generated by applying a 100 W radio frequency electrical signal. Before starting the deposit, a spray of the target was performed for 10 min with the shutter in the closed position. After that time the shutter opened to begin the deposit process. Under those conditions, the resulting deposition rate was 42 nm / min, previously determined from the use of a Dektak 3030ST contact profilometer on a series of calibration samples. Once the total deposition time was adjusted to the required thickness of 420 nm and the sheet deposited, the sample was extracted to the introduction chamber and finally to the outside. The same procedure was repeated to manufacture 30 sensors with a zinc nitride sheet thickness of 200 nm and 630 nm, adjusting the total deposition time to obtain the required thicknesses.
    Deposit of metal contacts
    The substrate with the deposited 420 nm zinc nitride sheet was placed back in the introduction chamber to deposit metal contacts. Before closing the introduction chamber, a mechanical mask was placed on the surface to isolate the two areas where the contacts were deposited. The introduction chamber was closed and the sample was transferred to the growth chamber. 5
    In the growth chamber, the sample faced an aluminum blank of 99.999% purity. An Ar flow of 40 sccm was introduced until a working pressure of 10-2 mbar was reached, which allowed the generation of a plasma by means of a 250 W direct current electrical signal. In this case, the aluminum cathode was pulverized during one minute before opening the shutter for the tank. Under these conditions, the rate of 10 deposit was 100 nm / min. Thus, after 2 min of deposit, 200 nm thick contacts were obtained. Finally, the sample was extracted abroad for later characterization. The same procedure was repeated to deposit the metal contacts on the sensors manufactured with a thickness of zinc nitride sheet of 200 nm and 630 nm.
    Optical and electrical sensor reading 15
    To measure the electrical resistance of the sensor manufactured with the 420 nm zinc nitride sheet, a silver epoxy conductor was used to connect electrical wires over the contacts. The sensor was connected in series with a resistance between 100 k and 10 M. The initial resistance of the sensor varied in a wide range from 10 k to 1 M and depended on the thickness of the layer and the sample size. The resistance of the sensor 20 increased smoothly with exposure to moisture, suffering a drastic increase when reaching a critical time that led the sheet to present resistances greater than 10 M. In parallel, the material was transforming its appearance from a black opaque material to a transparent material.
    The device was characterized by determining the resistance value as a function of time 25 while maintaining control of the relative humidity in the air. The humidity control was done using a humidifier and a commercial semiconductor device from Honeywell (HIH-4000) whose calibration curve was available on the component data sheet. These elements were housed next to the sensor developed in a waterproof hood. The sensor resistance was monitored using a voltage divider circuit 30 in which the resistor connected in series had a value 10 times higher than that of the newly manufactured sensor. The procedure allowed electrically calibrating the life of the sheet according to the dose of moisture received, from the data recorded by an acquisition card connected to a computer. the same
    Measurement procedure was performed on the sensors with a zinc nitride layer thickness of 200 nm and 630 nm. Figure 6 shows the results obtained for the different humidity doses in the sensor manufactured at 200 nm thick zinc nitride layer. It is shown that sensors subjected to high relative humidity increase their resistance to the threshold value more quickly than those subjected to low relative humidity.
    Additionally, the resistivity of the samples was determined with a four-point measuring system of the Dumas house, equipped with a Keithley 220 current source and a Keythley 619 multimeter. The change in optical characteristics was made using transmission spectroscopy in a spectrophotometer PerkinElmer Lambda 1050 which 10 included Xe and deuterium lamps. Measurements of spectroscopic ellipsometry in external reflection were also performed using a Horiba-Jobin-Yvon Uvisel system. Figure 7 shows the results obtained for the ellipsometric parameters as a function of different humidity doses in the 630 nm thick zinc nitride layer sensor. The increase in the number of oscillations reflects the change in the optical constants of the sensor.
    权利要求:
    Claims (17)
    [1]
    1. Humidity sensor for the detection of accumulated humidity by electronic and optical reading, comprising a solid support and a sheet of zinc nitride with a thickness between 10 nm and 100 µm, where the sheet of zinc nitride is arranged on the solid support. 5

    [2]
    2. Moisture sensor according to claim 1, wherein the solid support is rigid or flexible.

    [3]
    3. Moisture sensor according to claims 1 or 2, wherein the solid support is selected from glass, quartz, sapphire, polyethylene terephthalate, polyamide, polycarbonate, silicon, gallium nitride, zinc oxide, copper, aluminum and brass.

    [4]
    4. Moisture sensor according to any one of claims 1 to 3, wherein the thickness of the zinc nitride sheet is between 100 nanometers and 15 630 nanometers.

    [5]
    5. Moisture sensor according to claims 1 to 4, further comprising two insulated contacts of metal materials disposed on the zinc nitride sheet. twenty

    [6]
    6. Moisture sensor according to claim 5, wherein the metallic material of the insulated contacts is selected from aluminum, gold, silver, platinum, titanium, nickel, tin, indium, chromium, tungsten, copper and combinations thereof.
     25
    [7]
    7. Moisture sensor according to any one of claims 1 to 6, further comprising a voltage detector, wherein the zinc nitride sheet is electrically connected to the voltage detector.

    [8]
    8. Moisture sensor according to any of claims 5 and 7, wherein the zinc nitride sheet 30 is electrically connected to the voltage detector through the contacts arranged on the zinc nitride sheet.

    [9]
    9. The humidity sensor according to claim 7 or 8, wherein the voltage detector is a voltage divider or a radiofrequency identification reader. 35
    [10]
    10. Humidity sensor according to any one of claims 7 to 9, wherein the voltage detector is electrically connected to a Bluetooth technology emitting device for wireless communication with an external receiver.

    [11]
    11. Method of manufacturing the humidity sensor as defined in any one of claims 1 to 10 comprising:
    a) provide a solid support, and
    b) deposit a sheet of zinc nitride with a thickness between 10 nm and 100 µm on the solid support of step a) at pressures between 10-1 and 10-8 mbar. 10

    [12]
    12. A method according to claim 11 wherein the zinc nitride sheet is deposited on the solid support in step b) by sputtering in alternating current (RF) or by pulsed direct current in the presence of a nitrogen plasma and noble gases. fifteen

    [13]
    13. The method according to claims 11 or 12, further comprising a stage after step b) where two insulated contacts of metal materials are deposited on the zinc nitride sheet of step b).
     twenty
    [14]
    14. The method according to claim 13, wherein the two insulated contacts of metallic materials are deposited on the zinc nitride sheet of step b) by sputtering at pressures between 10-1 and 10-8 mbar using a mechanical mask.
     25
    [15]
    15. Use of the humidity sensor according to any one of claims 1 to 10 for the detection of moisture in food, electronic products, drugs, weapons, construction elements and works of art.

    [16]
    16. Use of the humidity sensor according to any one of claims 1 to 10 for the detection of perspiration in humans, animals or plants.

    [17]
    17. Use of the humidity sensor according to any of claims 1 to 10 for detection of exhaled water vapors
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    同族专利:
    公开号 | 公开日
    WO2018024932A1|2018-02-08|
    ES2657123B1|2018-12-04|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JPS63139241A|1986-12-02|1988-06-11|Nippon Telegr & Teleph Corp <Ntt>|Diode type humidity sensor|
    JP2006133192A|2004-11-09|2006-05-25|Nippon Soken Inc|Capacitance humidity sensor and its manufacturing method|
    US20090035865A1|2007-08-01|2009-02-05|Demoor Colette Pamela|Moisture sensor|
    US20100307238A1|2009-06-05|2010-12-09|The Governors Of The University Of Alberta|Humidity sensor and method of manufacturing the same|
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