阅读说明：本技术 气体传感系统及气体传感器 (Gas sensing system and gas sensor ) 是由 李娜 梁文杰 安飞 杨哲 孙冰 张树才 金艳 于 2020-04-10 设计创作，主要内容包括：本发明涉及气体传感技术领域,公开一种气体传感系统及气体传感器。所述气体传感系统包括：气体传感模块,集成有传感微芯片,所述传感微芯片能够根据不同的气体产生至少一路电信号；信号检测模块,用于获取所述传感微芯片产生的一路或多路电信号,并测量所述电信号对应的电阻值；信号处理模块,与所述信号检测模块连接,用于根据所述电信号对应的电阻值的变化情况确定所述电信号对应的气体的类别和浓度。本发明的传感微芯片能够对多种气体产生响应,信号检测模块能够同时获取并测量传感微芯片产生的多路电信号,无需设置多个传感模块和信号检测模块,减小系统体积,提高集成度,在实现复杂气氛检测同时满足微型化要求。(The invention relates to the technical field of gas sensing, and discloses a gas sensing system and a gas sensor. The gas sensing system includes: the gas sensing module is integrated with a sensing microchip, and the sensing microchip can generate at least one path of electric signals according to different gases; the signal detection module is used for acquiring one or more paths of electric signals generated by the sensing microchip and measuring a resistance value corresponding to the electric signals; and the signal processing module is connected with the signal detection module and used for determining the category and the concentration of the gas corresponding to the electric signal according to the change condition of the resistance value corresponding to the electric signal. The sensing microchip can respond to various gases, the signal detection module can simultaneously acquire and measure the multi-channel electric signals generated by the sensing microchip, a plurality of sensing modules and signal detection modules are not required to be arranged, the system volume is reduced, the integration level is improved, and the miniaturization requirement is met while the complex atmosphere detection is realized.)

1. A gas sensing system, the system comprising:

the gas sensing module is integrated with a sensing microchip, and the sensing microchip can generate at least one path of electric signals according to different gases;

the signal detection module is used for acquiring one or more paths of electric signals generated by the sensing microchip and measuring a resistance value corresponding to the electric signals;

and the signal processing module is connected with the signal detection module and used for determining the category and the concentration of the gas corresponding to the electric signal according to the change condition of the resistance value corresponding to the electric signal.

2. The gas sensing system of claim 1, wherein the sensing microchip comprises a micro-heating structure and a sensing structure;

the micro heating structure comprises a plurality of heating zones with different temperatures;

the sensing structure comprises a plurality of measuring electrodes and gas sensitive films coated on the measuring electrodes, wherein the materials of the gas sensitive films coated on the measuring electrodes are different;

the measuring electrodes are respectively arranged in the corresponding heating areas and generate a plurality of paths of electric signals.

3. The gas sensing system according to claim 2, wherein the signal detection module comprises an analog switch circuit, a driving circuit and an analog-to-digital conversion circuit which are connected in sequence;

the analog switch circuit is connected with the measuring electrode and is used for acquiring an analog electric signal generated by the measuring electrode;

the analog-to-digital conversion circuit is used for converting the analog electric signal into a digital signal and outputting the digital signal.

4. The gas sensing system according to claim 3, wherein said analog switching circuit is a four-way analog switching circuit connected to said plurality of measuring electrodes for obtaining said analog electrical signals generated by said plurality of measuring electrodes.

5. The gas sensing system according to claim 4, wherein the driving circuit is a four-way driving circuit, an input terminal of the four-way driving circuit is correspondingly connected with an output terminal of the four-way bidirectional analog switch circuit, and an output terminal of the four-way driving circuit is connected with the analog-to-digital conversion circuit.

6. The gas sensing system of claim 2, wherein the signal processing module comprises:

and the singlechip is used for determining the type and the concentration of the gas corresponding to the electric signal according to the change condition of the resistance value corresponding to the electric signal and outputting a type signal and a concentration signal of the gas.

7. The gas sensing system of claim 6, further comprising:

and the heating circuit is connected with the single chip microcomputer and used for providing heating voltage for the micro-heating structure.

8. The gas sensing system of claim 7, wherein the micro-heating structure comprises a heating electrode, the heating electrode being connected to the heating circuit.

9. The gas sensing system of claim 6, further comprising:

and the alarm module is connected with the singlechip and used for receiving the category signal and the concentration signal and generating an alarm signal when the concentration signal exceeds a preset threshold value.

10. The gas sensing system of claim 6, further comprising:

and the wireless communication module is connected with the singlechip and is used for wirelessly transmitting the category signal and the concentration signal.

11. The gas sensing system of claim 6, further comprising:

the temperature and humidity monitoring module is connected with the single chip microcomputer and used for monitoring the ambient temperature and the ambient humidity in real time and outputting a temperature signal and a humidity signal;

the single chip microcomputer is further used for determining the type and concentration of the gas corresponding to the electric signal according to the temperature signal, the humidity signal and the conversion condition of the resistance value corresponding to the electric signal.

12. The gas sensing system of claim 6, wherein the gas sensing module and the signal detection module are powered by the single-chip microcomputer.

13. The gas sensing system of claim 2, wherein the gas sensitive membrane is comprised of a metal oxide semiconductor nanomaterial.

14. The gas sensing system of claim 13, wherein the metal oxide semiconductor nanomaterial is one or more of WO3, SnO2, CuO, In2O3, NiO, MoO 3.

15. A gas sensor comprising a gas sensing system according to any one of claims 1 to 14.

Technical Field

The invention relates to the technical field of gas sensing, in particular to a gas sensing system and a gas sensor.

Background

With the improvement of living standard and the increasing attention on environmental protection, the detection of various poisonous and harmful gases, the monitoring of air pollution and industrial waste gas and the detection of human living environment quality have higher requirements. The rapid development of microelectronics, micromachining technology and automation and intelligence technology makes the gas sensor have small volume, low price, convenient use and convenient carrying. In order to meet the requirements of wide fields, the novel portable gas sensor has the characteristics of miniaturization, integration, multifunction, intellectualization and systematization. The Micro-Electro-Mechanical System (MEMS) device has the advantages of small volume, light weight, low energy consumption, short response time, and the like, and promotes the development of miniaturization, intelligence, low power consumption, and integration of the gas sensor, and the microstructure gas sensor is developed accordingly.

The principle of the MEMS gas-sensitive micro-heating sensor is that a micro planar multi-layer heater is manufactured on a substrate material by adopting an MEMS technology, so that a semiconductor oxide sensitive material is heated to a certain temperature, the chemical activity of the semiconductor oxide sensitive material is effectively excited and reacts with target gas molecules to be detected, and the change of the conductivity of the gas-sensitive material is caused to realize the detection purpose.

The types of the mixed gas in the scene of the complex atmosphere environment may be more than ten, and if the complex atmosphere detection is to be realized, a sensing device capable of detecting multiple gases simultaneously is required. At present, a sensor device for detecting complex atmosphere generally adopts a plurality of same microchip units which are independently arranged to form a sensor array, and the complex atmosphere detection function is realized by detecting the resistance change of a plurality of micro heating chips. Because each microchip of the sensor array needs to be provided with a heating structure and a detection circuit independently, the integral integration level of the device is not high, and the advantages of small volume and low energy consumption of the semiconductor gas sensing device cannot be embodied.

Disclosure of Invention

The invention aims to provide a gas sensing system which is high in integration level and can realize complex atmosphere detection.

In order to achieve the above object, the present invention provides a gas sensing system comprising:

the gas sensing module is integrated with a sensing microchip, and the sensing microchip can generate at least one path of electric signals according to different gases;

the signal detection module is used for acquiring one or more paths of electric signals generated by the sensing microchip and measuring a resistance value corresponding to the electric signals;

and the signal processing module is connected with the signal detection module and used for determining the category and the concentration of the gas corresponding to the electric signal according to the change condition of the resistance value corresponding to the electric signal.

Further, the sensing microchip comprises a micro-heating structure and a sensing structure; the micro heating structure comprises a plurality of heating zones with different temperatures; the sensing structure comprises a plurality of measuring electrodes and different gas sensitive films coated on the corresponding measuring electrodes, the measuring electrodes are respectively arranged in the corresponding heating zones, and the measuring electrodes generate multiple paths of electric signals.

Furthermore, the signal detection module comprises an analog switch circuit, a driving circuit and an analog-to-digital conversion circuit which are connected in sequence; the analog switch circuit is connected with the measuring electrode and is used for acquiring an analog electric signal generated by the measuring electrode; the analog-to-digital conversion circuit is used for converting the analog electric signal into a digital signal and outputting the digital signal.

Furthermore, the analog switch circuit is a four-way analog switch circuit, and the four-way analog switch circuit is connected with the plurality of measuring electrodes and is used for acquiring the analog electric signals generated by the plurality of measuring electrodes.

Furthermore, the driving circuit is a four-way driving circuit, the input ends of the four-way driving circuit are correspondingly connected with the output ends of the four-way bidirectional analog switch circuit, and the output ends of the four-way driving circuit are connected with the analog-to-digital conversion circuit.

Further, the signal processing module includes:

and the singlechip is used for determining the type and the concentration of the gas corresponding to the electric signal according to the change condition of the resistance value corresponding to the electric signal and outputting a type signal and a concentration signal of the gas.

Further, the system further comprises:

and the heating circuit is connected with the single chip microcomputer and used for providing heating voltage for the micro-heating structure.

Further, the micro-heating structure comprises a heating electrode, and the heating electrode is connected with the heating circuit.

Further, the system further comprises:

and the alarm module is connected with the singlechip and used for receiving the category signal and the concentration signal and generating an alarm signal when the concentration signal exceeds a preset threshold value.

Further, the system further comprises:

and the wireless communication module is connected with the singlechip and is used for wirelessly transmitting the category signal and the concentration signal.

Further, the system further comprises:

the temperature and humidity monitoring module is connected with the single chip microcomputer and used for monitoring the ambient temperature and the ambient humidity in real time and outputting a temperature signal and a humidity signal;

the single chip microcomputer is further used for determining the type and concentration of the gas corresponding to the electric signal according to the temperature signal, the humidity signal and the conversion condition of the resistance value corresponding to the electric signal.

Furthermore, the gas sensing module and the signal detection module are powered by the single chip microcomputer.

Further, the gas sensitive film is composed of a metal oxide semiconductor nanomaterial.

Further, the metal oxide semiconductor nano material is one or more of WO3, SnO2, CuO, In2O3, NiO and MoO 3.

The invention also provides a gas sensor which comprises the gas sensing system.

The gas sensing system adopts a sensing microchip formed by multiple nano gas-sensitive sensing materials as a gas sensing module, measures the resistance values corresponding to multiple paths of electric signals of the sensing microchip through a signal detection module, and determines the category and the concentration of gas corresponding to each electric signal according to the change conditions of the resistance values of the multiple paths of electric signals through a signal processing module, thereby realizing the detection function of the multiple gas-sensitive materials in a complex atmosphere and simultaneously detecting the concentrations of multiple harmful gases. This gas sensing system's sensing microchip can produce the response to multiple gas, and signal detection module can acquire and measure the multichannel signal of telecommunication that the sensing microchip produced simultaneously, need not to set up a plurality of sensing modules and signal detection module, reduces the system volume, improves the integrated level, realizes that complicated atmosphere detects and satisfies the miniaturization requirement simultaneously.

Additional features and advantages of embodiments of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention without limiting the embodiments of the invention. In the drawings:

fig. 1 is a block diagram of a gas sensing system according to an embodiment of the present invention;

FIG. 2 is a block diagram of the signal detection module of FIG. 1;

FIG. 3 is a schematic diagram of the analog switching circuit of FIG. 2;

FIG. 4 is a schematic diagram of the drive circuit of FIG. 2;

FIG. 5 is a schematic diagram of the analog-to-digital conversion circuit of FIG. 2;

fig. 6 is a circuit schematic of the signal processing module of fig. 1.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Example one

Fig. 1 is a block diagram of a gas sensing system according to an embodiment of the present invention. As shown in fig. 1, the gas sensing system provided in this embodiment includes a gas sensing module, a signal detection module, and a signal processing module. The gas sensing module is integrated with a sensing microchip, and the sensing microchip can generate at least one path of electric signals according to different gases. The signal detection module is used for acquiring one or more paths of electric signals generated by the sensing microchip and measuring the resistance value corresponding to the electric signals. The signal processing module is connected with the signal detection module and used for determining the type and concentration of the gas corresponding to the electric signal according to the change situation of the resistance value corresponding to the electric signal.

The sensing microchip comprises a micro heating structure and a sensing structure; the micro heating structure comprises a plurality of heating zones with different temperatures; the sensing structure comprises a plurality of measuring electrodes and different gas sensitive films coated on the corresponding measuring electrodes, the measuring electrodes are respectively arranged in the corresponding heating zones, and the measuring electrodes generate multiple paths of electric signals. The multiple heating zones of the micro-heating structure provide corresponding heating temperatures for the multiple gas sensitive membranes of the sensing structure. When a gas sensitive film on the surface of the measuring electrode is contacted with a certain gas, the resistivity is obviously changed at a specific temperature, and the type and the concentration of the gas are determined according to the change situation of the resistance values of the measuring electrodes in different heating areas. Because the response temperatures of different sensing materials are different, the micro-heating structure provides heating zones with different temperatures for heating different sensing materials, so that the detection of multiple sensing materials on a single microchip at different temperatures is realized, and the complex atmosphere detection function is realized.

The gas sensitive film is made of metal oxide semiconductor nano materials. The metal oxide semiconductor nano material is one or more of WO3, SnO2, CuO, In2O3, NiO and MoO 3. The size of the sensing material particles is regulated to enable the size to be less than or equal to the Debye length (D) to form a nanometer scale, in the aspect of dimension, the one-dimensional heterostructure has a large length-diameter ratio, which means that more surface atoms can participate in surface gas-solid reaction, so that the target gas is promoted to be rapidly identified through reaction, and the two-phase particles (ions) are doped to reduce an electron depletion layer, so that the reaction activation potential barrier is reduced, and the dissociation and reaction rate of gas molecules on the surface of the material are improved. Therefore, the nano gas-sensitive sensing material has the advantages of high response sensitivity, quick response time and recovery time and low detection limit (<10ppb), compared with a common bulk material, the nano gas-sensitive sensing material has the advantages that the response of a nano material sensor is greatly improved, the detection lower limit is lower, the detection of the ppb level with ultra-low concentration can be realized, the response time is faster, and the alarm within 10 seconds can be realized.

Fig. 2 is a block diagram of a signal detection module. As shown in fig. 2, the signal detection module includes an analog switch circuit, a driving circuit, and an analog-to-digital conversion circuit, which are connected in sequence. The analog switch circuit is connected with the measuring electrode and used for acquiring the analog electric signal generated by the measuring electrode. The analog-to-digital conversion circuit is used for converting the analog electric signal into a digital signal and outputting the digital signal. As shown in fig. 3, the analog switch circuit in this embodiment is a four-way and two-way analog switch circuit, and the four-way and two-way analog switch circuit is connected to the plurality of measuring electrodes and is configured to obtain the analog electrical signals generated by the plurality of measuring electrodes. For example, each analog switch of the CD4066 four-way bidirectional analog switch has three terminals of input, output and control, and can simultaneously acquire 4 paths of analog electrical signals generated by the sensor array, thereby realizing multiplexing of the analog signals. As shown in fig. 4, the driving circuit in this embodiment is a four-way driving circuit, and a TLV3544 four-channel operational amplifier is adopted, so that low-level or high-level analog input can be processed without external signal conditioning hardware. As shown in fig. 5, the analog-to-digital conversion circuit in this embodiment adopts an AD7833 bridge circuit to accurately measure the resistance change of the measurement electrode, and converts an analog electrical signal into a digital signal for output. The input end of the four-way driving circuit is correspondingly connected with the output end of the four-way bidirectional analog switch circuit, the output end of the four-way driving circuit is connected with the analog-to-digital conversion circuit, and the circuit structure can measure the resistance change of a plurality of measuring electrodes at the same time to realize multi-way signal detection.

Fig. 6 is a schematic circuit diagram of a signal processing module, and as shown in fig. 6, the signal processing module includes a single chip microcomputer, and the single chip microcomputer is configured to determine the type and concentration of the gas corresponding to the electrical signal according to a change condition of the resistance value corresponding to the electrical signal, and output a type signal and a concentration signal of the gas. In this embodiment, an STM32 single chip microcomputer is adopted, an algorithm for determining the type and concentration of the gas is written into a program code, the program code is burnt into the STM32 single chip microcomputer, and the STM32 single chip microcomputer determines the type and concentration of the gas corresponding to the digital signal according to the digital signal output by the analog-to-digital conversion circuit, so that a gas detection function is realized. The algorithm of the gas sensing system comprises a temperature and humidity compensation algorithm, a signal drift calibration algorithm, a multi-channel signal identification algorithm, an alarm value and a transmission display mode setting.

The gas sensing system also comprises a heating circuit, wherein the heating circuit is connected with the single chip microcomputer and is used for providing heating voltage for the micro-heating structure. The micro-heating structure comprises a heating electrode, the heating electrode is connected with the heating circuit, and heating voltage/current is provided through the heating circuit.

The gas sensing system of this embodiment still includes alarm module, wireless communication module and humiture monitoring module. The alarm module is connected with the single chip microcomputer and used for receiving the category signals and the concentration signals and generating alarm signals when the concentration signals exceed a preset threshold value. And the preset threshold is uploaded to the singlechip through the burning port. The alarm module comprises a light emitting diode and a buzzer, when the single chip microcomputer judges that the concentration signal exceeds a preset threshold value, an alarm signal is generated, the light emitting diode is lightened, the buzzer sounds, and danger is warned. The wireless communication module is connected with the single chip microcomputer and used for wirelessly transmitting the category signals and the concentration signals to external monitoring equipment, so that real-time remote reading of gas concentration data is facilitated. The wireless communication module is, for example, a ZigBee communication module, a Bluetooth communication module or an RS-232/485 communication module.

The temperature and humidity monitoring module is connected with the single chip microcomputer and used for monitoring the ambient temperature and the ambient humidity in real time and outputting a temperature signal and a humidity signal; the single chip microcomputer is further used for determining the type and concentration of the gas corresponding to the electric signal according to the temperature signal, the humidity signal and the change situation of the resistance value corresponding to the electric signal. For example, the single chip microcomputer reasonably compensates the influence of the temperature and the humidity on the resistance value according to a pre-programmed program instruction (the change relation between the temperature and the humidity and the resistance value), and improves the accuracy of gas detection.

The gas sensing system of this embodiment adopts the loop power supply, can satisfy the power supply demand of singlechip through lithium ion battery or domestic No. 5 battery, and gas sensing module and signal detection module are supplied power by the singlechip. For example, the singlechip outputs 0-5V heating voltage to the gas sensing module to supply power to the heating electrode, and the heating electrode provides different heating temperatures for each measuring electrode. The voltage of the heating electrode can be adjusted according to the actual temperature requirement, the adjustable voltage precision is 0.2V, and the average distribution is in the range of 0-5V. The driving capability can reach more than 100mA by outputting current to the heating electrode through a TLV3544 four-channel operational amplifier.

The gas sensing system of the embodiment adopts a sensing microchip formed by multiple nanometer gas sensitive sensing materials as a gas sensing module, the signal detection module is used for measuring the resistance values corresponding to multiple paths of electric signals of the sensing microchip, and the signal processing module is used for determining the category and the concentration of gas corresponding to each electric signal according to the change conditions of the resistance values of the multiple paths of electric signals, so that the cross detection of the multiple gas sensitive materials at different temperatures is realized, namely the concentration of multiple harmful gases is detected at the same time. This gas sensing system's sensing microchip can produce the response to multiple gas, and signal detection module can acquire and measure the multichannel signal of telecommunication that the sensing microchip produced simultaneously, need not to set up a plurality of sensing modules and signal detection module, reduces the system volume, improves the integrated level, realizes that complicated atmosphere detects and satisfies the miniaturization requirement simultaneously.

The signal processing module of this embodiment adopts the singlechip to handle multichannel signal of telecommunication, and whole sensing system is suitable for same set of drive circuit and transmission circuit, has greatly reduced the required space of circuit, solves the bulky problem of current portable gas sensor, satisfies gas sensing device's integration, miniaturized demand, can be in portable detection application in various engineering environment.

The embodiment of the invention also provides a gas sensor which comprises the gas sensing system.

The gas sensor of the invention adopts the semiconductor oxide sensing principle, and preferably selects the gas-sensitive nanometer material with high response sensitivity, rapid response time and corresponding recovery time and low detection limit (<10ppb) to be integrated on a micro-heating chip processed by the MEMS technology. The surface of the gas sensor can be packaged by adopting a ceramic shell, and the surface of the gas sensor is provided with a porous structure, so that the target gas can be fully diffused. The gas sensor provided by the invention can realize cross detection of multiple gas sensing materials on one micro-heating chip structure of a set of heating structure at different temperatures, improves the accuracy of the response value of multi-component gas detection, and can realize ppb-ppm level detection for single or mixed gas.

While the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the embodiments of the present invention are not limited to the details of the above embodiments, and various simple modifications can be made to the technical solution of the embodiments of the present invention within the technical idea of the embodiments of the present invention, and the simple modifications are within the scope of the embodiments of the present invention. It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention will not be described separately for the various possible combinations.