Signal acquisition interface circuit for nanometer material gas sensor

Abstract

The utility model provides a signal acquisition interface circuit for a nanometer material gas sensor, and belongs to the technical field of signal acquisition. The problem that a signal acquisition circuit of an existing nano material gas sensor is low in precision and reliability is solved. Comprising at least one signal acquisition circuit, the signal acquisition circuit is connected with a microcontroller through an ADC circuit, the microcontroller is further connected with a display module and a communication interface through wires, the signal acquisition circuit adopts a high-resistance negative feedback I / V amplification circuit, and the high-resistance negative feedback I / V amplification circuit comprises a COMS operational amplifier and a feedback resistor. The feedback resistor is connected between the inverting input end and the output end of the COMS operational amplifier, and the in-phase input end of the COMS operational amplifier is grounded; the high-precision output resistance acquisition device is applied to high-precision output resistance acquisition of the nano-material gas sensor.

Description

TECHNICAL FIELD

[0001] The utility model provides a signal acquisition interface circuit for nanometer material gas sensor belongs to signal acquisition circuit technical field. BACKGROUND

[0002] In the middle of the twentieth century, people found that semiconductor thin films are sensitive to gas concentration, and after that, gas sensors prepared by metal oxide (ZnO, SnO2, Fe2O3, etc.) materials have been rapidly developed. Traditional metal oxide semiconductor gas sensors have been widely used in qualitative detection of toxic and harmful gases due to their easy preparation and low price. However, such sensors usually have poor selectivity and unsatisfactory stability, and are not suitable for situations where the gas concentration needs to be accurately measured. With the research on semiconductor thin film materials, people found that when the size of a material in one dimension is reduced to nanoscale, the physical properties of the material will change greatly. This is because nanomaterials have a large specific surface area, which can provide more adsorption sites and active sites, so they can achieve very high sensitivity to a single gas.

[0003] The output resistance range of the gas sensor designed based on metal oxide semiconductor material can reach 1KΩ-100MΩ in actual application. Since the output signal range of this type of sensor is very large, it is extremely important to obtain accurate sensor input-output characteristic curves to improve measurement accuracy. In summary, developing a high-precision signal acquisition and processing system for nanomaterial gas sensors is the only way to apply such sensors in practice. Improving the performance and reliability of sensors and reducing production costs is also an inevitable trend in industrial development. At the same time, accurate testing systems also provide strong help for the research of new nanomaterial gas sensors. The above content is a new technology that has not been developed on the market yet. How to consider the actual needs of users and meet their needs to the greatest extent is a need to explore. Utility model content

[0004] The utility model discloses in order to solve the low precision, low reliability of existing nanometer material gas sensor's signal acquisition circuit exist problem, proposes a kind of signal acquisition interface circuit for nanometer material gas sensor, by using high resistance negative feedback I / V amplification circuit, and then more accurate and effective data collected by gas sensor is displayed.

[0005] The utility model discloses a technical scheme for a signal acquisition interface circuit for a nanometer material gas sensor, which comprises at least one signal acquisition circuit, the signal acquisition circuit is connected to a microcontroller through an ADC circuit, and the microcontroller is further connected to a display module and a communication interface through wires, wherein the signal acquisition circuit adopts a high-resistance negative feedback I / V amplification circuit, the high-resistance negative feedback I / V amplification circuit comprises a COMS operational amplifier and a feedback resistor, the feedback resistor is connected between the inverting input terminal and the output terminal of the COMS operational amplifier, and the non-inverting input terminal of the COMS operational amplifier is grounded.

[0006] Further, the COMS operational amplifier adopts an operational amplifier of model LMC6062.

[0007] Further, the microcontroller communicates with a PC host computer through the communication interface.

[0008] Further, the communication interface adopts a UART serial communication bus protocol to realize the communication between the microcontroller and the PC host computer.

[0009] The PC host computer is connected to a CH340 module, realizes serial communication through two RXD and TXD pins, and the microcontroller and the PC host computer are set with the same baud rate to perform data transmission and reception.

[0010] Further, the main control chip in the microcontroller adopts an STM32F103 series single-chip microcomputer.

[0011] Further, the display module adopts an OLED display module.

[0012] Further, the microcontroller is further connected to an expandable interface.

[0013] Further, the signal acquisition circuit is specifically provided with four channels, and the four-channel signal acquisition circuits are all connected to the microcontroller through ADC circuits.

[0014] Further, the signal acquisition circuit can measure the nanometer material gas sensor with an output resistor range of 1KΩ-100MΩ.

[0015] The utility model has the beneficial effects compared with the prior art:

[0016] 1. The sensor circuit designed based on the STM32 of the utility model has low cost, is provided with an expandable interface, is convenient for research and development design, and is simple to use and convenient for people to use.

[0017] 2. The signal acquisition circuit, i.e., the high-resistance negative feedback I / V circuit, designed in the utility model has accurate data transmission, can achieve real-time, and the system formed by negative feedback has high control precision, stable system operation and noise suppression.

[0018] 3, the utility model discloses a resistance type gas sensor measuring circuit can be well applied to gas sensor test system, lay a solid foundation for the research and application of novel nanometer material gas sensor. BRIEF DESCRIPTION OF DRAWINGS

[0019] The utility model makes further explanation from the following combined with the drawing:

[0020] Figure 1 It is high resistance negative feedback I / V amplification principle diagram of the utility model;

[0021] Figure 2 It is main control chip minimum system principle diagram of the utility model;

[0022] Figure 3 It is gear shifting flow chart of the utility model;

[0023] Figure 4 It is system block diagram of the utility model. DETAILED DESCRIPTION

[0024] As Figures 1 to 4 The utility model discloses a signal acquisition interface circuit for nanometer material gas sensor, including main control chip, signal acquisition circuit, display module and communication interface, and main control chip is as control core control range's automatic switching, signal's capture, data acquisition and host computer communication, shows sensor real -time information simultaneously.

[0025] The main control chip adopts STM32F103 series single-chip microcomputer in the embodiment. The display module is an OLED display module.

[0026] The signal acquisition circuit is a high-resistance negative feedback I / V amplification circuit, wherein LMC6062 is used as an operational amplifier, the input stage of LMC6062 adopts MOS tube design, the input resistance is high, the offset current is very small, the input current voltage noise is extremely low, and it is very suitable for micro-current signal amplification.

[0027] The communication interface is a UART serial communication bus protocol, and communication between the main control chip and a PC host computer is realized. The PC host computer is connected with a CH340 module, so that serial communication can be realized through two pins of RXD and TXD, and data can be transmitted and received by setting the same baud rate for both sides.

[0028] In the research of semiconductor gas sensor materials, the internal resistance of some sensors can be as high as GΩ, and the detection current signal is as low as pA. The detection of this type of signal belongs to the detection of extremely weak micro-current signal, and the signal-to-noise ratio is extremely low, so the detection is difficult. Some traditional proportional amplification type and current integration type, resistance voltage division method and Wheatstone bridge method are relatively expensive in design, large in size and heavy in weight, but the application scene of micro-current detection is more and more, so it has important practical significance and application value to design a micro-current detection instrument with small size, light weight and low cost based on high resistance negative feedback amplification circuit.

[0029] As Figure 4 shown, it is a block diagram of a signal acquisition interface circuit for a nanomaterial gas sensor according to the embodiment, and the circuit specifically comprises:

[0030] (1) The utility model discloses a 4 data acquisition channels can be measured 4 way gas sensor simultaneously, also leave the expansion interface, can increase the number of channels.

[0031] (2) The utility model discloses 4 kinds of selectable measuring circuit, can stable measurement output resistance range in 1KΩ-100MΩ gas sensor. In 1KΩ-1MΩ resistance range, the precision reaches 1%, 1MΩ-100MΩ resistance range, the precision reaches 5%;The specific method of gear shifting is as Figure 3 shown: first, the ADC starts sampling, and the single-chip microcomputer obtains the AD conversion value from the ADC. If the gear position of the amplification circuit is in the low gear at this time and the AD conversion value is greater than 2.4V, the single-chip microcomputer pin will drive the relay gear to switch to the high gear. If the current is in the high gear and the AD conversion value is less than 0.002V, it means that the current range does not meet the current measured value, so the single-chip microcomputer pin level value should be changed to drive the relay to switch the amplification circuit gear to the low gear. But if the current range is in the low gear and the AD conversion value is less than the minimum resolution, or the current range is in the high gear and the AD conversion value is greater than the maximum range, it means that the current measurement value has exceeded the range, so the sampling should be stopped to avoid damaging the AD part of the single-chip microcomputer and an alarm should be sent.

[0032] (3) In the process of channel scanning, first, channel 1 (high resistance negative feedback amplification circuit) is scanned, and the control process of the amplification circuit measurement of the channel includes range switching and ADC data sampling. Next, the remaining three channels are scanned, and the control process of the circuit measurement of each channel includes timer capture integration pulse and other operations.

[0033] (4) When the scanning of the channel is completed, the system will preliminarily process all the measured raw data, and the data acquisition part is designed with an external display OLED terminal, so that the resistance change of the sensor can be directly observed. At the same time, it is sent to the PC host computer through the serial communication interface. The single data acquisition time is less than 30 ms; the host computer communicates with the circuit system, and can record the data of 2 channels at the same time. After processing the data, the response curve is drawn, and the response time and sensitivity of the gas sensor are quantitatively analyzed.

[0034] It should be noted that the connection relationship between the components and modules of the utility model is determined and can be realized. Except for the special description in the embodiments, the specific connection relationship can bring corresponding technical effects. Based on the premise of not relying on the corresponding software program execution, the technical problems proposed by the utility model are solved. The model, connection mode, and conventional use method of the components, modules, and specific components in the utility model, and the expected technical effects brought by the above technical features, except for the specific description, belong to the public content disclosed in the patents, journal papers, technical manuals, technical dictionaries, textbooks, and other existing technologies obtained by the technical personnel in the field before the application date. It does not need to be repeated. The technical scheme provided in the case is clear, complete, and can be realized, and the corresponding entity product can be reproduced or obtained according to the technical means.

[0035] Finally, it should be noted that: the above embodiments are only used to illustrate the technical scheme of the utility model, but not to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical scheme recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical scheme deviate from the scope of the technical scheme of the embodiments of the utility model.

Claims

1. A signal acquisition interface circuit for a nanomaterial gas sensor, characterized by: The signal acquisition circuit includes at least one signal acquisition circuit, the signal acquisition circuit is connected with the microcontroller through the ADC circuit, the microcontroller is further connected with a display module and a communication interface through wires, wherein the signal acquisition circuit adopts a high-resistance negative feedback I / V amplification circuit, the high-resistance negative feedback I / V amplification circuit includes a COMS operational amplifier and a feedback resistor, the feedback resistor is connected between the inverting input terminal and the output terminal of the COMS operational amplifier, and the non-inverting input terminal of the COMS operational amplifier is grounded.

2. The signal acquisition interface circuit for a nanomaterial gas sensor according to claim 1, wherein: The COMS operational amplifier adopts an operational amplifier of LMC6062 type.

3. The signal acquisition interface circuit for a nanomaterial gas sensor according to claim 1, wherein: The microcontroller communicates with the PC host computer through the communication interface.

4. The signal acquisition interface circuit for a nanomaterial gas sensor according to claim 3, wherein: The communication interface adopts a UART serial communication bus protocol to realize the communication between the microcontroller and the PC host computer. The CH340 module is connected to the PC host computer, serial communication is realized through two pins of RXD and TXD, and the microcontroller and the PC host computer are set with the same baud rate for data transmission and reception.

5. The signal acquisition interface circuit for a nanomaterial gas sensor according to any one of claims 1-4, characterized in that: The main control chip in the microcontroller adopts an STM32F103 series single-chip microcomputer.

6. The signal acquisition interface circuit for a nanomaterial gas sensor according to any one of claims 1-4, characterized in that: The display module adopts an OLED display module.

7. The signal acquisition interface circuit for a nanomaterial gas sensor according to any one of claims 1-4, wherein: The microcontroller is further connected with an extensible interface.

8. The signal acquisition interface circuit for a nanomaterial gas sensor according to any one of claims 1-4, wherein: The signal acquisition circuit is specifically provided with four signal acquisition circuits, and the four signal acquisition circuits are connected to the microcontroller through ADC.

9. The signal acquisition interface circuit for a nanomaterial gas sensor according to claim 8, wherein: The signal acquisition circuit can measure the gas sensor of the nanomaterial with the output resistance ranging from 1KΩ to 100MΩ.

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