TW202011011A - Portable gas sensing apparatus with two functional electrode pairs and ultraviolet activated ternary nanocomposite - Google Patents

Abstract

The present invention discloses a portable gas sensing apparatus, which includes a ternary nanocomposite composed of ZnO nanowires, metal oxide (e.g. CuxO) and precious metal (e.g. Au) as a sensing film for adsorbing gas molecules, so as to increase adsorbing capability and detection sensitivity. The ultraviolet (UV) light emitting from the UV LED in the sensing apparatus irradiates onto the sensing film to achieve fast equilibrium of gas molecule adsorption and desorption. The Si chip accommodating the sensing film has two electrode pairs for sensing and heating to reduce the interference of humidity on gas sensing.

Description

Portable gas sensing device with dual-function electrode pair and ultraviolet activated ternary nanometer composite material

The invention relates to a portable gas sensing device with dual-function electrode pairs and ultraviolet-activated ternary nanocomposite materials.

With the development of industry, the problem of environmental pollution is becoming more and more serious, so gas sensors used in environmental detection are also gradually paid attention to. As long as the concentration of harmful gas is in the range of tens to hundreds of ppb, it will affect human health, so sensors that can respond sensitively to low concentrations of gas are becoming more important. Therefore, the development of sensors that can detect low gas concentrations is of great market value.

To develop novel gas sensors, the present invention uses metal oxide nanomaterials (eg, tin dioxide, titanium dioxide, zinc oxide, etc.). Metal oxide nanomaterials have a high surface-to-volume ratio, good chemical stability, and have semiconductor characteristics due to structural defects in nanomaterials. When gas molecules are adsorbed on the surface of the metal oxide nanomaterial, the conductivity of the nanomaterial changes greatly.

Zinc oxide is one of the metal oxide nanomaterials that can be used for gas sensing. It can form one-dimensional nanostructures such as nanowires, nanopillars, and nanoribbons. It has oxygen vacancy and zinc gaps. interstitial) Two kinds of defects generate free electrons, so zinc oxide nanomaterials are N-type semiconductors without doping.

Oxidizing gas molecules are adsorbed on the surface of the nanomaterial, and capture the internal free electrons, so that the gas molecules form negative ions, and cause a depletion layer in the nanomaterial, so the free electrons decrease, and the conductivity of the nanomaterial will decrease (That is, the resistance rises). The characteristics of reducing gas are the opposite. The gas molecules are adsorbed on the surface of the nano material, which increases the conductivity of the nano material (that is, the resistance decreases).

In addition to being adsorbed on the surface of the nanomaterial, gas molecules will also be desorbed by the surface of the nanomaterial. When the adsorption and desorption of gas molecules reach equilibrium, in different gas concentration environments, the adsorption ratio of gas molecules on the surface of the nanomaterial is also different, so that the equivalent resistance value of the nanomaterial is different, so the equivalent resistance changes The ratio can be known as the gas concentration of the environment near the nano material.

The desorption rate of gas molecules at room temperature is slow. Therefore, in gas sensing, increasing the desorption rate to quickly achieve balance can improve the sensing rate and sensitivity. There are two ways to increase the desorption rate. One is to increase the working temperature of the nanomaterial (about hundreds of degrees Celsius), so that the desorption rate of the gas molecules is greatly increased. The disadvantage is that the nanomaterial is easier to age. Another method is to irradiate the nano material with light to generate electrons and holes in the nano material. The gas molecules of the oxidizing gas are adsorbed on the surface of the nano material in the form of negative ions. The holes can neutralize the gas negative ions and self-contain The surface of the rice material is desorbed, which is also called the photo-activation mode. Taking zinc oxide nanomaterials as an example, the energy gap is 3.37 eV, so ultraviolet light must be irradiated to help desorption of gas molecules from the surface of zinc oxide nanomaterials, also known as ultraviolet light activation mode.

The ultraviolet light activation mode makes the electrons and holes generated inside the nano material easily recombine in the nano material. In order to reduce the recombination rate of the present invention, nanostructures of different materials such as semiconductors, metal oxides or precious metals are grown on the surface of the zinc oxide nanostructures. Since the other nanostructure has a different energy band structure from the original zinc oxide nanostructure, and electrons and holes move to different materials, the recombination rate of electrons and holes can be reduced. That is, the ability of the nanomaterial to desorb gas molecules is enhanced, so that the adsorption and desorption are quickly balanced, and the sensitivity of gas sensing is also greatly improved.

Therefore, the present invention discloses a gas sensing device, including: a substrate; a ternary composite material film, which is disposed on the substrate and is composed of precious metal particles, copper oxide nanomaterials and zinc oxide nanomaterials; a light-emitting diode The body is arranged above the ternary composite film and is at a distance from the ternary composite film to store a local space. The light-emitting diode is used to emit an ultraviolet light; two sensing electrodes are arranged on the three The ternary composite film is connected between the ternary composite film and the substrate, and is used when the ternary composite film is irradiated by the ultraviolet light and a gas to be measured in the local space is absorbed by the ternary composite film At the time, sensing the resistance value of the ternary composite film; and a processor, electrically connected to the two sensing electrodes, for calculating a concentration of the gas to be measured according to the resistance value.

According to a main technical point of view, the present invention also discloses a method for sensing the concentration of a gas to be measured using a gas sensing device, wherein the gas sensing device includes a sensing film, and the sensing film is Before the gas sensing, the measured resistance value is R _0. The method includes: at time T, the resistance value of the sensing film is measured as R; find △R/R0, where △R=R- R0; according to a table lookup method, obtain a concentration of the gas to be measured at the time T.

The invention also discloses a gas sensing device, including: a sensing film with an upper surface for adsorbing a gas molecule; and a resistance sensing device electrically connected to the sensing film for sensing the sensing A resistance value of the thin film; and a processor electrically connected to the resistance sensing device, and calculating a concentration of the gas molecule according to the resistance value, characterized in that the sensing film includes: a gas molecule adsorption material, used To adsorb the gas molecules; an adsorption enhancement material to enhance the ability of the sensing film to adsorb the gas molecule; and an adsorption re-enhancement material to further enhance the ability of the sensing film to adsorb the gas molecule.

The invention also discloses a gas sensing device, including: a sensing film with an upper surface for adsorbing a gas molecule; and a resistance sensing device electrically connected to the sensing film for sensing the sensing One of the resistance values of the film; a heating sheet, disposed near the sensing film, for heating the sensing film so that a space above one of the upper surfaces has a specific humidity; and a processor electrically connected to the resistance sense Measuring device, and calculating a concentration of the gas molecule according to the resistance value.

The invention also discloses a gas sensing device, including: a sensing film with an upper surface for adsorbing a gas molecule; and a resistance sensing device electrically connected to the sensing film for sensing the sensing One of the resistance values of the film; a photo-activation device, provided above the upper surface, for photo-activation of the upper surface, so as to enhance the desorption of the gas molecules by the sensing film, so as to quickly reach a balance between adsorption and desorption; and a treatment Is electrically connected to the resistance sensing device, and calculates a concentration of the gas molecule according to the resistance value.

10‧‧‧Portable gas sensing device

100‧‧‧ substrate

101‧‧‧sensing film

102‧‧‧First electrode

103‧‧‧Second electrode

104‧‧‧UV LED

105‧‧‧third electrode

106‧‧‧The fourth electrode

200‧‧‧Control processing system

201‧‧‧ processor

202‧‧‧The first digital analog converter

203‧‧‧The second digital analog converter

204‧‧‧The first analog to digital converter

210‧‧‧Amplification gain identification calculation module

211‧‧‧heating calculation module

212‧‧‧Resistance change rate△R/R ₀ calculation module

213‧‧‧△R/R ₀ conversion concentration calculation module

301‧‧‧ LED drive module

302‧‧‧Heating drive module

303‧‧‧Amplification gain identification conversion module

304‧‧‧Front module of resistance sensing signal circuit

305‧‧‧Amplification gain selection circuit

306‧‧‧switch

307‧‧‧Temperature and humidity sensing module

308‧‧‧Wireless transmission module

309‧‧‧ Antenna

400‧‧‧smart device

401‧‧‧picture

Figure 1: Schematic diagram of the portable gas sensing device of the present invention; Figure 2: Schematic diagram of the application of the control data of the gas sensing device of the present invention to a smart phone or other smart handheld device 400; Figure 3: The unit , The comparison diagram of the equivalent resistance change rate of three different nanomaterials of binary and ternary materials in the same concentration of NO ₂ gas; Figure 4: The ternary nanomaterial sensing film of the present invention is obtained by electron microscope Observed structure diagram; Figure 5: Schematic diagram of the equivalent resistance change rate of the ternary nanometer material sensing film of the present invention for sensing the change of the same concentration of NO ₂ gas relative to humidity; Figure 6: The heating of the present invention Schematic diagram of the temperature change of the electrode relative to the substrate at different voltages;

The portable gas sensing device of the present invention uses a ternary nanocomposite composed of three nanomaterials of zinc oxide nanowires plus metal oxides such as copper oxide (Cu _x O) and precious metals such as gold (Au) The material is made of a sensing film that adsorbs gas molecules. In addition to further promoting the separation of electrons and holes, its empty depletion layer will also become larger. The noble metal particles become an electron gathering place, which can promote the adsorption of gas molecules, thus improving the sensitivity of gas sensing and enhancing the adsorption capacity of nano materials. Precious metals include gold, silver, ruthenium, rhodium, palladium, osmium, iridium and/or platinum.

The portable gas sensing device of the invention utilizes ultraviolet light to activate the ternary nanocomposite material of the sensing film to help the gas molecules desorb from the surface of the ternary nanocomposite material, quickly achieve a balance between adsorption and desorption, and improve the sense Measuring rate and sensitivity.

According to the measurement result of the temperature and humidity sensor, the portable gas sensing device of the present invention determines the expected temperature and humidity values around the sensing film after analysis and calculation by the heating calculation module, and then uses the heating electrode to adapt Heat the sensing film to achieve the expected temperature and humidity values, and increase the sensitivity of gas sensing.

The portable gas sensing device of the present invention uses the sensing electrode to obtain the change ratio of the equivalent resistance value caused by the gas molecule to the ternary nanometer composite material in the sensing film, and calculates the gas around the sensing film according to the calculation Molecular concentration.

The portable gas sensing device of the present invention adaptively adjusts the amplification gain of the equivalent resistance value with the control switch of the amplification gain selection circuit to increase the sensitivity and accuracy of gas sensing.

It is worth noting that the sensing film of the portable gas sensing device of the present invention not only uses a ternary nanocomposite material composed of three nanomaterials composed of zinc oxide nanowires plus metal oxides and precious metals, but also A binary nanocomposite composed of copper oxide/zinc oxide nanowires can be used to sense the gas.

Please refer to FIG. 1, which is a portable gas sensing device 10 of the present invention having a dual-function electrode pair and UV-activated nanocomposite, including a device composed of a ternary nanocomposite on the surface of a substrate 100 The sensing film 101 and the management and processing system 200. The surface of the sensing film 101 can absorb the gas molecules to be measured in the surrounding environment, so that the first pair of electrode measurement sensing film 101 composed of the first electrode 102 and the second electrode 103 installed under the sensing film 101 is adsorbed on The equivalent resistance value and change formed by the gas molecules on the surface are analyzed by the management and processing system 200 to obtain the characteristics of the gas molecule.

The management and processing system 200 includes a processor 201. The processor 201 is electrically connected to the first digital-to-analog (D/A) converter 202 with a bus to control its output, so that the light emitting diode (LED) current driving module 301 according to the Output, drive the ultraviolet light-emitting diode 104 which is arranged above the sensing film 101 and is at a distance from the sensing film 101 and has a local space. The sensing film 101 is irradiated with ultraviolet light to activate the sensing film 101 to improve The sensing film 101 senses the rate and sensitivity of the equivalent resistance value.

Since the temperature and humidity of the surrounding environment have a great influence on the sensing film 101 composed of nanometer composite materials to measure the gas molecules to change their equivalent resistance value, the gas sensing device 10 of the present invention is provided with a heating electrode or a micro Heater, when the temperature or humidity of the surrounding environment of the gas sensing device 10 exceeds a threshold, the processor 201 activates the heating drive module 302 to heat the electrode or microheater to connect the substrate 100 with the sensing film 101 and its surrounding environment Slightly heated, when the ultraviolet light-emitting diode 104 is irradiated with ultraviolet light and excites the sensing film 101, the local space temperature above the sensing film 101 is slightly increased, so that moisture and water molecules leave the sensing area to increase the reaction Speed and stability further improve the sensitivity of sensing.

The heating calculation module 211 reads the temperature and humidity of the surrounding environment of the sensing film 101 measured by the temperature and humidity sensing module 307 by the processor 201, analyzes and calculates it, and adaptively controls the second through the bus bar according to the result The voltage output of the digital-to-analog (D/A) converter 203 enables the heating drive module 302 to drive a second pair of electrodes composed of the third electrode 105 and the fourth electrode 106 under the sensing film 101 according to the output, The sensing film 101 above and the substrate 100 below are provided with thermal energy. The third electrode 105 and the fourth electrode 106 can be replaced by miniature heaters. The miniature heaters can be disposed between the substrate 100 and the sensing film 101 under the substrate 100 or in an appropriate space.

Since the temperature and humidity sensor 307 continuously transmits the measurement results of the humidity and temperature around the sensing film 101 to the heating calculation module 211 to continuously adjust the heating electrode (the third electrode 105 and the fourth electrode 106) to the sensing film 101 The applied heat can thus maintain the control sensing film 101 around a favorable specific ambient humidity and temperature, so as to reduce the influence of humidity on the measurement of the equivalent resistance value of the sensing film 101.

In order to uniformly heat the sensing film 101 and obtain the equivalent resistance value of the sensing film 101, the first electrode 102 and the second electrode 103 and the third electrode 105 and the fourth electrode 106 are evenly arranged on the sensing film 101 and the substrate Four directions between 100. For example, the first electrode 102 and the second electrode 103 are arranged along both ends of the X-axis direction (not shown in FIG. 1), and the third electrode 105 and the fourth electrode 106 are along the Y-axis direction (not shown in the first Figure) at both ends of the configuration. On the other hand, the arrangement of the sensing film 101 in the gas sensing device 10 allows the gas molecules to be measured in the surrounding environment to flow in the space on the upper surface of the sensing film 101 and is adsorbed by the sensing film 101.

The first electrode 102 and the second electrode 103 send the sensing signals measured by the equivalent resistance value of the sensing film 101 formed by the gas molecules adsorbed on the surface of the sensing film 101 to the amplification gain discrimination conversion mode Group 303. The amplification gain discrimination transformation module 303 includes an amplifier, a passive component network, an amplification gain selection circuit 305, a switch 306, and an amplification gain discrimination calculation module 210 in the processor 201.

The aforementioned sensing signal enters the amplification gain discrimination conversion module 303, and after being pre-processed by the resistance sensing signal circuit pre-module 304, it is transmitted to the input port of the amplification gain discrimination conversion module 303 and applied by the amplifier Amplified, the output port of the amplification gain discrimination conversion module 303 is sent to the first analog-to-digital (A/D) converter 204 in the processor 201 electrically connected thereto, and converted into digital data for the processor 201 The amplification gain identification calculation module 210 determines the open and closed circuits of the switch 306, and adaptively adjusts the gain of the amplification gain selection circuit 305 to optimize the sensing signal, provide good conditions for subsequent calculation and analysis, and improve the gas sensation of the present invention The sensing sensitivity and accuracy of the measuring device 10.

The amplification gain discrimination conversion module 303 processes different sensing signals of the sensing film 101 to determine the open circuit and the closed circuit of the switch 306. The steps include:

(1) When the equivalent resistance value of the sensing signal read by the analog-to-digital converter 204 of the processor 201 is low resistance, the amplification gain discrimination calculation module 210 controls the switch 306 of the amplification gain selection circuit 305 to be in an open state ;

(2) When the equivalent resistance value corresponding to the sensing signal read by the first analog-to-digital converter 204 of the processor 201 falls within a critical range formed by the maximum critical value and the minimum critical value, the amplification gain discrimination calculation module 210 starts calculation: the processor 201 continuously reads five sensing signals and compares each two adjacent sensing signals. If the equivalent resistance value corresponding to the two adjacent sensing signals increases upward, and the When the equivalent resistance value corresponding to the last sensing signal of 5 consecutive readings is higher than the maximum threshold value, the amplifier gain discrimination calculation module 210 of the processor 201 controls the switch 306 of the amplifier gain selection circuit 305 to be in a closed circuit state, The amplification gain is increased, and a larger equivalent resistance value can be read; on the contrary, if the equivalent resistance value corresponding to two adjacent sensing signals decreases downward, and the last one of the five consecutive readings should be read When the equivalent resistance value corresponding to the sensing signal is lower than the minimum critical value, the amplifier gain discrimination calculation module 210 of the processor 201 controls the switch 306 of the amplifier gain selection circuit 305 to be in an open state, so that the amplifier gain is reduced and can be read Take a lower equivalent resistance value.

(3) However, if the equivalent resistance value corresponding to the last one of the five consecutive readings is not within this critical range, the amplification gain discrimination calculation module 210 of the processor 201 controls the amplification gain selection circuit 305 The switch 306 is maintained in a closed or open state.

After the aforementioned steps, the gain adjustment conversion module 303 optimizes the gain adjustment of the sensing signals measured under different gas concentrations and different environments, which is beneficial to the equivalent of the subsequent sensor 201 to the sensing film 101 caused by the gas concentration The calculation and analysis of the change rate of the resistance value and the concentration conversion further improve the sensing sensitivity and accuracy of the gas sensing device 10 of the present invention.

In order to calculate and analyze the equivalent resistance value corresponding to the sensing signal and thereby determine the characteristics of the sensing gas, the gas sensing device 10 of the present invention is equipped with a resistance change rate ΔR/R ₀ calculation module 212 and a processor 201 △R/R ₀ conversion concentration calculation module 213, where R ₀ is the internal equivalent resistance value of the sensing film 101 preset in the processor 201, and the processor 201 reads the corresponding equivalent of the sensing signal at time T Resistance value R, resistance change rate in processor 201 △R/R _{0 The} calculation module 212 subtracts R and R ₀ to obtain △R=RR ₀ and stores it in memory (not shown). The △R/R ₀ conversion concentration calculation module 213 has a built-in resistance change rate △R/R ₀ value list corresponding to different concentrations of the gas to be measured, and the gas concentration value to be measured corresponding to each △R/R ₀ value, so The △R/R ₀ conversion concentration calculation module 213 can calculate the concentration value of the gas to be measured according to the aforementioned △R/R ₀ value by using a table lookup method.

In addition, the processor 201 is provided with a wireless transmission module 308, such as a Bluetooth module or a WI-FI module, and an antenna 309, which can calculate the ambient temperature and humidity values sensed by the temperature and humidity sensing module 307 and the calculation results The resistance change rate of the measured gas △R/R ₀ , gas concentration and gas concentration versus time change chart, etc., are sent to a smartphone or other smart device 400, so that the foregoing data can be displayed on the smartphone or other smart devices in two-dimensional coordinates The screen 401 of the device 400 is as shown in FIG. 2.

Furthermore, a smartphone or other smart device 400 may be configured with an arithmetic module similar to the △R/R ₀ calculation module 212 and the △R/R ₀ conversion concentration calculation module 213, and the gas sensor 10 measures The corresponding equivalent resistance value of the signal is transmitted to the smart phone or other smart device 400, and the smart phone or other smart device 400 is further calculated, and the result is displayed on the screen 401 of the smart phone or other smart device 400.

On the other hand, the user can set and display the operating parameters of the gas sensing device 10 on the screen 401 of the smartphone or other smart device 400, such as the temperature, humidity, and ultraviolet light of the sensing area above the sensing film 101 The current value of the polar body 104 and the resistance change rate of the gas to be measured, and transmit the foregoing operating parameters to the gas sensing device 10 through the wireless transmission module 308, so that the processor 201 of the gas sensing device 10 according to the received operating parameters , To adjust the light emitting diode current driving module 301 and the heating driving module 302, and control the test of the gas sensing device 10.

Please refer to FIG. 3, which is to verify that the sensing film of the ternary nanocomposite material composed of gold particles/copper oxide/zinc oxide nanowires used in the present invention has the same NO ₂ as the sensing film of other different nanomaterials Comparison graph of resistance change rate of gas concentration. It can be seen from Figure 3 that at the same concentration of NO ₂ gas, the resistance change rate detected by the one-element nanomaterial sensing film composed of zinc oxide (ZnO) nanowires is about 320%, and copper oxide ( The resistance change rate of the sensing film of the binary nanocomposite material composed of Cu _x O)/zinc oxide (ZnO) nanowires is about 386%, and the gold (Au) particles/copper oxide used in the present invention (Cu _x O)/ZnO (ZnO) nanowire ternary nanocomposite sensing film has a resistance change rate of about 447%. Obviously, under the same NO ₂ gas concentration, the resistance change rate detected by the sensing film of the ternary nanocomposite material used in the present invention is greater than that of the binary nanocomposite material of copper oxide/zinc oxide nanowire The sensing film is larger than the unary material sensing film of zinc oxide nanowires. In other words, the sensing film of the ternary nanocomposite material used in the present invention has the highest detection sensitivity of the resistance change rate.

Please refer to FIG. 4, which is an electron microscope structure diagram of a sensing film 101 of a ternary nanocomposite material composed of gold particles/copper oxide/zinc oxide nanowires. The composition percentage of the gold particles/copper oxide/zinc oxide nanowires in FIG. 4 is about 2:18:80.

Please refer to FIG. 2 and FIG. 5 again. FIG. 5 is to verify that the gas sensing device 10 of the present invention has the same NO ₂ gas concentration and no or slightly heating of the sensing area. Different humidity is relative to the equivalent Schematic diagram of the resistance change rate, where the curve formed by the round dots is the equivalent resistance change rate of the sensing film 101 when the sensing area is not heated, and the curve formed by the square dots is the sensing film when the sensing area is slightly heated 101's equivalent resistance change rate. It can be seen from FIG. 5 that in the case where the sensing area is not heated, the resistance change rate will increase greatly with the increase of humidity, that is, the equivalent resistance change rate of the sensing film 101 changes greatly at different humidity; otherwise In the case where the sensing area is slightly heated, although the sensed equivalent resistance change rate decreases, for the same concentration of NO ₂ gas, the equivalent resistance change rate does not change significantly with increasing humidity, also That is, the equivalent resistance change rate sensed by the sensing film 101 is relatively stable at different humidity. Therefore, in the present invention, the sensing area is heated by a heating electrode or a micro heater, and when the ultraviolet light emitting diode 104 excites the gas to be measured in the sensing area to react with the sensing film 101, the local space of the sensing area The temperature rises slightly, within a few tens of degrees Celsius higher than the ambient temperature, which allows moisture to leave the sensing area quickly, avoiding the thickening of the water film above the sensing film 101 of the ternary nanocomposite and reducing the amount of sensing film 101 Errors due to changes in humidity when measuring the equivalent resistance value, which in turn increases measurement stability and accuracy.

Please refer to FIG. 6, which is a schematic diagram of the temperature change of the substrate 100 measured when different voltages are applied to the heating electrode of the ternary nanocomposite material used in the gas sensing device 10 of the present invention. When the heating electrode is applied with different voltages, it can cause the local temperature of the sensing area to rise to drive off the moisture and water molecules.

The portable gas sensing device of the present invention uses a ternary consisting of three kinds of nanomaterials including zinc oxide (ZnO) nanowires plus metal oxides such as copper oxide (Cu _x O) and precious metals such as gold (Au) Nanocomposite material as a sensing film that adsorbs gas molecules can improve the sensitivity of gas sensing, can further enhance the adsorption capacity of nanomaterials, and avoid the interference of sensing caused by changes in the humidity of the working environment.

In addition, the portable gas sensing device of the present invention utilizes ultraviolet light to irradiate the sensing film of the ternary nanocomposite material to improve the sensing rate and sensitivity. The portable gas sensing device of the present invention activates the heating electrode to heat the surrounding environment of the sensing film according to the measurement result of the temperature and humidity sensor, and controls the humidity and temperature of the surrounding environment of the sensing film to reduce the humidity measurement Influence of equivalent resistance value. The invention adaptively adjusts the amplification gain of the equivalent resistance value by the control switch of the amplification gain selection circuit, and further increases the sensitivity of measuring the equivalent resistance value.

Examples

1. A gas sensing device, comprising: a substrate; a ternary composite material film, arranged on the substrate and composed of precious metal particles, copper oxide nanomaterials and zinc oxide nanomaterials; a light emitting diode, set There is a local space above the ternary composite material film and a distance away from the ternary composite material film, the light emitting diode is used to emit an ultraviolet light; two sensing electrodes are arranged on the ternary composite material The ternary composite material film is connected between the film and the substrate, and is used when the ternary composite material film is irradiated by the ultraviolet light and a gas to be measured in the local space is adsorbed by the ternary composite material film. Measuring the resistance value of the ternary composite material film; and a processor electrically connected to the two sensing electrodes for calculating a concentration of the gas to be measured according to the resistance value.

2. The gas sensing device according to embodiment 1, wherein the substrate is a silicon substrate, and the gas sensing device further includes: two heating electrodes, disposed between the ternary composite material film and the substrate, for The temperature of one of the surroundings of the ternary composite film is raised by the power of a heating driving module.

3. The gas sensing device according to embodiment 1 or 2, wherein the heating driving module is electrically connected to the processor, and the processor includes a temperature and humidity sensing module for sensing the surrounding environment The temperature or humidity, when the temperature or the humidity exceeds a threshold, the processor activates the heating drive module to heat the substrate and the ternary composite material film.

4. The gas sensing device according to any one of embodiments 1 to 3, wherein the two sensing electrodes are arranged along both ends of the X-axis direction, and the two heating electrodes are arranged along both ends of the Y-axis direction.

5. The gas sensing device according to any one of embodiments 1 to 4, wherein the gas sensing device further comprises: a current driving module electrically connected to the light-emitting diode; and a heating driving module Group, electrically connected to the two heating electrodes; a resistance sensing signal circuit pre-module, electrically connected to the two sensing electrodes; and an amplification gain selection circuit with an input port and an output port, the input The port is electrically connected to the front-end module of the resistance sensing signal circuit, and the processor includes: a first digital-to-analog (D/A) converter electrically connected to the current drive module to control the The output of the current drive module; a second digital analog (D/A) converter, electrically connected to the heating drive module, for controlling the output of the heating drive module; and a first analog digital (A/ D) The converter is electrically connected to the output port for receiving the output signal of the amplification gain selection circuit.

6. The gas sensing device according to any one of embodiments 1 to 5, wherein the precious metal particles are selected from one of the group consisting of gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum And the copper oxide nanomaterial and the zinc oxide nanomaterial are one-dimensional nanomaterials.

7. A method for sensing the concentration of a gas to be measured using a gas sensing device, wherein the gas sensing device includes a sensing film, and the measured resistance value of the sensing film before performing gas sensing Is R0, the method includes: at time T, the resistance value of the sensing film is measured as R; find △R/R0, where △R=R-R0; according to a table look-up method, obtain the gas to be measured A concentration at this time T.

8. The method as described in embodiment 7, wherein the gas sensing device further includes a processor, a resistance sensing signal circuit pre-module and an amplification gain selection circuit, the processor includes an electrical connection to the amplification gain An analog-to-digital (A/D) converter, a switch of the selection circuit, and a gain discrimination calculation module electrically connected to the amplification gain selection circuit, wherein the method further includes: (1) when the A/D conversion When a reading resistance value of the device at time T is a low resistance, the switch is in an open state; (2) When the reading resistance value of the A/D converter at time T is located at a maximum threshold and a When the minimum critical value is within a critical range, the gain identification algorithm module starts to receive 5 consecutive reading resistance values and compares the two adjacent reading resistance values. When the 5 consecutive reading resistance values When it is increasing upwards, and the last reading resistance value is higher than the maximum threshold value, the switch is placed in a closed circuit state to read a higher reading resistance value; and when the 5 consecutive reading resistance When the value decreases downward, and the last reading resistance value is lower than the minimum threshold value, the switch is placed in the open state to read a smaller reading resistance value; and (3) when the A/ When the read resistance value of the D converter is not within the critical range at time T, the switch is maintained in the open circuit state or the closed circuit state.

9. The method according to embodiment 7 or 8, wherein the gas sensing device further includes a processor and an amplification gain selection circuit, wherein the processor includes: a temperature and humidity sensing module for measuring the Sensing the temperature and humidity around the film; a first analog-to-digital (A/D) converter for receiving a read resistance value output by the amplification gain selection circuit; and a gain discrimination calculation module for controlling A switch of the amplification gain selection circuit, wherein: when the reading resistance value is a low resistance value, the switch is in an open circuit state, when the reading resistance value is located at a maximum critical value and a minimum critical value Within a critical range, the gain discrimination calculation module starts to receive the reading resistance value of 5 consecutive pens, and compares the reading resistance value of every two adjacent pens, wherein: when the reading resistance of 5 consecutive pens When the value increases upward, and the last reading resistance value is higher than the maximum threshold value, the switch is put into a closed state to read a larger reading resistance value; and when the continuous 5 When the reading resistance value of the pen decreases downward, and the reading resistance value of the last pen is lower than the minimum and the critical value, the switch is in an open state to read the smaller reading resistance value And when the read resistance value is not within the critical range, the switch is maintained in the original open circuit state or the closed circuit state.

10. The method as described in any one of embodiments 7 to 9, further comprising a calculation method in which the processor calculates the molecular concentration value of the gas to be measured corresponding to an equivalent resistance, the calculation method includes using A △R/R ₀ calculation module and a △R/R ₀ conversion concentration calculation module: use this △R/R ₀ calculation module to obtain a resistance value difference △R=RR ₀ , the calculation results in this △R/ R ₀ ; use the △R/R ₀ conversion concentration calculation module to calculate the corresponding gas concentration value to be measured according to the ratio, and establish a correspondence table between each complex ratio and each complex gas concentration value; and use a The table look-up method obtains the corresponding gas concentration value to be measured from the correspondence table according to each complex ratio.

11. The method according to any one of embodiments 7 to 10, wherein the gas sensing device further includes a wireless transmission module, wherein the wireless transmission module is used to place or sense an environment in which the sensing film is located The temperature and humidity values, the ratio of the gas to be measured and the concentration value of the gas to be measured are sent to a smart device, and the smart device is used to return the complex control parameters to the gas sensing device for corresponding testing .

12. A gas sensing device, comprising: a sensing film having an upper surface for adsorbing a gas molecule; and a resistance sensing device electrically connected to the sensing film for sensing the sensing film A resistance value; and a processor, electrically connected to the resistance sensing device, and calculating a concentration of the gas molecule according to the resistance value, characterized in that the sensing film includes: a gas molecule adsorption material for adsorption The gas molecule; an adsorption enhancement material to enhance the ability of the sensing film to adsorb the gas molecule; and an adsorption re-enhancement material to further enhance the ability of the sensing film to adsorb the gas molecule.

13. A gas sensing device, comprising: a sensing film with an upper surface for adsorbing a gas molecule; and a resistance sensing device, electrically connected to the sensing film, for sensing the sensing film A resistance value; a heating sheet, disposed near the sensing film, for heating the sensing film so that a space above a top surface has a specific humidity; and a processor, electrically connected to the resistance sensing device And calculate a concentration of the gas molecule according to the resistance value.

14. A gas sensing device, comprising: a sensing film with an upper surface for adsorbing a gas molecule; and a resistance sensing device electrically connected to the sensing film for sensing the sensing film A resistance value; a photo-activation device, arranged above the upper surface, for photo-activation of the upper surface, so as to enhance the desorption of the gas molecules of the sensing film, so as to quickly reach a balance between adsorption and desorption; and a processor, It is electrically connected to the resistance sensing device, and calculates a concentration of the gas molecule according to the resistance value.

However, the diagrams and descriptions disclosed above are only preferred embodiments of the present invention. Those who are familiar with this art and who make modifications or equivalent changes in accordance with the spirit of the case should still be included in the scope of the invention application patent .

10‧‧‧Portable gas sensing device

100‧‧‧ substrate

101‧‧‧sensing film

102‧‧‧First electrode

103‧‧‧Second electrode

104‧‧‧UV LED

105‧‧‧third electrode

106‧‧‧The fourth electrode

200‧‧‧Control processing system

201‧‧‧ processor

202‧‧‧The first digital analog converter

203‧‧‧The second digital analog converter

204‧‧‧The first analog to digital converter

210‧‧‧Amplification gain identification calculation module

211‧‧‧heating calculation module

212‧‧‧Resistance change rate△R/R ₀ calculation module

213‧‧‧△R/R ₀ conversion concentration calculation module

301‧‧‧ LED drive module

302‧‧‧Heating drive module

303‧‧‧Amplification gain identification conversion module

304‧‧‧Front module of resistance sensing signal circuit

305‧‧‧Amplification gain selection circuit

306‧‧‧switch

307‧‧‧Temperature and humidity sensing module

308‧‧‧Wireless transmission module

309‧‧‧ Antenna

400‧‧‧smart device

401‧‧‧picture

Claims (14)

A gas sensing device includes: a substrate; a ternary composite material film, which is arranged on the substrate and is composed of precious metal particles, copper oxide nanomaterials, and zinc oxide nanomaterials; and a light emitting diode, which is arranged on the There is a local space above the ternary composite film and at a distance from the ternary composite film, the light emitting diode is used to emit an ultraviolet light; two sensing electrodes are arranged on the ternary composite film and The ternary composite film is connected between the substrates and used to sense the ternary composite film when the irradiated by the ultraviolet light and a gas to be measured in the local space is absorbed by the ternary composite film The resistance value of the ternary composite material film; and a processor, electrically connected to the two sensing electrodes, and used to calculate a concentration of the gas to be measured according to the resistance value. The gas sensing device according to item 1 of the patent application scope, wherein the substrate is a silicon substrate, and the gas sensing device further includes: two heating electrodes disposed between the ternary composite material film and the substrate, It is used to heat the power of a driving module to raise the temperature of the surrounding environment of the ternary composite film. The gas sensing device as described in item 2 of the patent application scope, wherein the heating driving module is electrically connected to the processor, and the processor includes a temperature and humidity sensing module for sensing the surrounding environment Temperature or humidity. When the temperature or the humidity exceeds a threshold, the processor activates the heating drive module to heat the substrate and the ternary composite film. The gas sensing device as described in item 2 of the patent application range, wherein the two sensing electrodes are arranged at both ends in the X-axis direction, and the two heating electrodes are arranged at both ends in the Y-axis direction. The gas sensing device as described in item 1 of the patent application scope, wherein the gas sensing device further comprises: a current driving module electrically connected to the light emitting diode; a heating driving module electrically connected to The two heating electrodes; a resistance sensing signal circuit pre-module, electrically connected to the two sensing electrodes; and an amplification gain selection circuit, having an input port and an output port, the input port is electrically connected to the A front-end module of the resistance sensing signal circuit, and the processor includes: a first digital-to-analog (D/A) converter electrically connected to the current drive module for controlling the output of the current drive module ; A second digital analog (D/A) converter, electrically connected to the heating drive module, for controlling the output of the heating drive module; and a first analog digital (A/D) converter, It is connected to the output port to receive the output signal of the amplifier gain selection circuit. The gas sensing device according to item 1 of the patent application scope, wherein the precious metal particles are selected from one of the group consisting of gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum, and the copper oxide The rice material and the zinc oxide nano material are one-dimensional nano materials. A method for sensing the concentration of a gas to be measured using a gas sensing device, wherein the gas sensing device includes a sensing film, and the measured resistance value of the sensing film before performing gas sensing is R ₀ , the method includes: at time T, the resistance value of the sensing film is measured as R; find △R/R0, where △R=R-R0; according to a table lookup method, obtain the gas under test A concentration at this time T. The method as described in item 7 of the patent application range, wherein the gas sensing device further includes a processor, a resistance sensing signal circuit pre-module, and an amplification gain selection circuit, the processor includes an electrical connection to the An analog-to-digital (A/D) converter, a switch of the amplification gain selection circuit, and a gain discrimination calculation module electrically connected to the amplification gain selection circuit, wherein the method further includes: (1) when the A/D When a reading resistance value of the D converter at time T is a low resistance, the switch is in an open circuit state; (2) When the reading resistance value of the A/D converter at time T is at a maximum threshold And within a critical range formed by a minimum critical value, the gain discrimination algorithm module begins to receive 5 consecutive reading resistance values and compares the two adjacent reading resistance values, wherein when the 5 consecutive readings When the resistance value increases upwards, and the last reading resistance value is higher than the maximum threshold value, the switch is placed in a closed circuit state to read a higher reading resistance value; and when the 5 consecutive readings When the resistance value decreases downward, and the last reading resistance value is lower than the minimum critical value, the switch is placed in the open state to read a smaller reading resistance value; and (3) When the read resistance value of the A/D converter is not within the critical range at time T, the switch maintains the open circuit state or the closed circuit state. The method as described in item 7 of the patent application scope, wherein the gas sensing device further includes a processor and an amplification gain selection circuit, the processor includes: a temperature and humidity sensing module for measuring the sensing Temperature and humidity around the film; a first analog-to-digital (A/D) converter to receive a read resistance value output by the amplification gain selection circuit; and a gain discrimination calculation module to control the amplification A switch of the gain selection circuit, wherein: when the reading resistance value is a low resistance value, the switch is in an open state, and when the reading resistance value is located at a threshold formed by a maximum critical value and a minimum critical value When it is within the range, the gain discrimination calculation module starts to receive the reading resistance value of 5 consecutive pens, and compares the reading resistance value of every two adjacent pens, wherein: when the reading resistance value of the 5 consecutive pens is When increasing upwards, and when the last reading resistance value is higher than the maximum threshold value, the switch is put into a closed state to read a larger reading resistance value; and when the five consecutive readings When the reading resistance value decreases downward, and the last reading resistance value is lower than the minimum threshold value, the switch is opened to read a smaller reading resistance value; and When the read resistance value is not within the critical range, the switch maintains the original open circuit state or the closed circuit state. The method as described in item 9 of the patent application scope further includes a calculation method in which the processor calculates the molecular concentration value of the gas to be measured corresponding to an equivalent resistance. The calculation method includes the use of a △R/R ₀ Calculation module and a △R/R ₀ conversion concentration calculation module: use this △R/R ₀ calculation module to get a resistance value difference △R=RR ₀ , the complex time point within a period of measurement time, the calculation is Out a ratio ΔR/R _{0 of the} difference between the resistance value and the first reading resistance value; use the △R/R ₀ conversion concentration calculation module to calculate the corresponding gas concentration value to be measured according to the ratio, Establishing a correspondence table between each of the complex ratios and each of the plurality of measured gas concentration values; and using a look-up table method to obtain the corresponding gas concentration value to be measured from the correspondence table according to each of the complex ratios. The method as described in item 10 of the patent application scope, wherein the gas sensing device further includes a wireless transmission module, wherein the wireless transmission module is used to sense the ambient temperature and humidity value of the sensing film and the to-be-measured The ratio of the gas and the concentration value of the gas to be measured are sent to a smart device, and the smart device is used to return the complex control parameters to the gas sensing device for corresponding testing. A gas sensing device includes: a sensing film having an upper surface for adsorbing a gas molecule; and a resistance sensing device electrically connected to the sensing film for sensing a resistance of the sensing film Value; and a processor, electrically connected to the resistance sensing device, and calculating a concentration of the gas molecule according to the resistance value, characterized in that the sensing film includes: a gas molecule adsorption material for adsorbing the gas Molecules; an adsorption enhancement material to enhance the ability of the sensing film to adsorb the gas molecules; and an adsorption re-enhancement material to further enhance the ability of the sensing film to adsorb the gas molecules. A gas sensing device includes: a sensing film having an upper surface for adsorbing a gas molecule; and a resistance sensing device electrically connected to the sensing film for sensing a resistance of the sensing film A heating sheet, which is arranged near the sensing film to heat the sensing film so that a space above the upper surface has a specific humidity; and a processor electrically connected to the resistance sensing device, and A concentration of the gas molecule is calculated based on the resistance value. A gas sensing device includes: a sensing film having an upper surface for adsorbing a gas molecule; and a resistance sensing device electrically connected to the sensing film for sensing a resistance of the sensing film Value; a photo-activation device, provided above the upper surface, for photo-activation of the upper surface, so as to enhance the desorption of the gas molecules of the sensing film, so that adsorption and desorption quickly reach a balance; and a processor, electrical connection The resistance sensing device calculates a concentration of the gas molecules according to the resistance value.

Images