High-sensitivity hydrogen concentration sensor based on thermal conductivity chip
By adopting a differential circuit design of dual MEMS thermal conductivity chips in the sensor, the problems of low detection sensitivity and large errors of traditional thermal conductivity sensors are solved, and high-sensitivity hydrogen concentration detection is achieved, and power consumption and preheating time are reduced.
Patent Information
- Application Number
- CN202323531648.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-25
- Publication Date
- 2025-03-14
- Estimated Expiration
- 2033-12-25
AI Technical Summary
Traditional thermal conductivity sensors have problems such as low detection sensitivity, large detection error, large temperature drift, difficulty in compensation of ambient temperature, and cross-sensitivity.
The differential circuit design based on dual MEMS thermal conductivity chips is adopted, and differential signals are detected and generated through open and closed MEMS chips respectively to improve detection accuracy and sensitivity.
High-sensitivity hydrogen concentration detection is achieved, reducing power consumption and preheating time, and improving the life and applicability of the sensor.
Smart Images
Figure CN222618538U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of gas concentration sensing, in particular to a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip. Background Art
[0002] Since traditional thermal conductivity sensors detect gas concentration by utilizing the property that the temperature of the sensor changes accordingly with the concentration of the measured gas, they have many problems such as low detection sensitivity, large detection error, large temperature drift, difficulty in ambient temperature compensation, and cross-sensitivity. Utility Model Content
[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model embodiment proposes a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip, which has the characteristics of low power consumption and long life. The utility model can greatly shorten the preheating process to 100ms, and it only takes 300ms to complete a gas concentration detection. Under the condition of constant voltage power supply, the power consumption of the utility model embodiment is much lower than that of the electrochemical principle and the semiconductor principle. Since there is no loss of chemical materials, the utility model has an ultra-long life.
[0004] According to an embodiment of the utility model, a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip comprises: a sensor analog front end part, a signal conditioning part, a data processing part, and a power supply part;
[0005] The sensor analog front end part includes a first MEMS chip, which converts the concentration change of the target gas into a tiny electrical signal according to a linear law, which serves as a signal source for the signal processing part;
[0006] The signal conditioning part includes a second MEMS chip, which conditions and amplifies the tiny electrical signal generated by the analog front end part of the sensor into a sampling signal with low noise and low temperature;
[0007] The data processing part includes a microcontroller chip, which converts the sampled signal into a digital signal and transmits it through communication;
[0008] The power supply part provides power supply for the sensor analog front-end part, signal conditioning part and data processing part.
[0009] Furthermore, the sensor analog front end part includes an open first MEMS chip, the second, fifth, fourth, seventh and eighth pins of the first MEMS chip are connected to the ground in parallel; the sixth pin of the first MEMS chip and the sixth pin of the second MEMS chip are connected in parallel to one end of the second resistor; the TH- pin of the first MEMS chip and the TH- pin of the second MEMS chip are connected in parallel; the TH+ pin of the first MEMS chip is connected to the AN2 end of the microcontroller chip; and the TH+ pin of the second MEMS chip is connected to the AN3 pin of the microcontroller chip.
[0010] Furthermore, the data conditioning part includes a sealed second MEMS chip, the second, fifth, fourth, seventh and eighth pins of the second MEMS chip are connected to the ground in parallel; the sixth pin of the second MEMS chip is connected to one end of the second resistor to provide the required MEMS chip working voltage; the first pin of the second MEMS chip is connected in parallel with the first pin of the first MEMS chip to provide signal input to the microcontroller chip; the third pin of the second MEMS chip provides signal input to the microcontroller chip.
[0011] Further, in the data processing part, the eighth pin of the microcontroller chip is connected in parallel with the third pin of the first MEMS chip and the AN2 end; the ninth pin of the microcontroller chip is connected in parallel with the third pin of the second MEMS chip and the AN3 end; the third and fourth pins of the microcontroller chip are connected in parallel with one end of the sixth capacitor and one end of the fifth capacitor to ground; the first and second pins of the microcontroller chip are connected in parallel with the other end of the sixth capacitor and one end of the third resistor; the forty-eighth pin of the microcontroller chip is connected in parallel with the other end of the third resistor, the other end of the fifth capacitor, and the VHT end; the forty-seventh pin of the microcontroller is connected to the second pin of the first interface socket, and the forty-sixth pin of the microcontroller is connected to the third pin of the first interface socket , the 45th chip of the microcontroller chip is grounded; the 40th pin and the 37th pin of the microcontroller chip are connected to the fourth pin of the second interface socket; the 39th pin of the microcontroller chip is connected to the third pin of the second interface socket; the 35th pin of the microcontroller chip is connected in parallel with the I2C1_SCL and SCL1 terminals; the 35th pin of the microcontroller chip is connected in parallel with the I2C1_SDA and SDA1 terminals; the 31st pin of the microcontroller chip is connected to I2C2_SDA; the 30th pin of the microcontroller chip is connected to I2C2_SDL; the 16th pin of the microcontroller chip is connected to the VHT_EN terminal; the 11th pin of the microcontroller chip is connected to the DAC terminal.
[0012] Furthermore, the first and third pins of the power control chip are connected in parallel with one end of the first capacitor, one end of the second capacitor, and the VDD end; the second pin of the power control chip is connected in parallel with the other end of the first capacitor and the other end of the second capacitor and is grounded; the fifth pin of the power control chip is connected in parallel with one end of the third capacitor, one end of the fourth capacitor, and the VHT end; the other end of the third capacitor and the other end of the fourth capacitor are grounded in parallel.
[0013] The technical solution provided by the embodiment of the utility model is based on the differential circuit design of dual MEMS thermal conductivity chips. Compared with traditional thermal conductivity products, the technical solution of the utility model has a strong low-temperature drift performance and a very high low-noise characteristic. The first MEMS thermal conductivity chip of the utility model is open for detecting gas, and the other MEMS thermal conductivity chip is closed for generating differential signals, which has a good detection effect on gas concentration, and is small in size, fast in response, flexible in subsequent data transmission and processing, highly customizable, and can be easily connected to various electronic systems, which is convenient for other electronic systems in need to expand the gas flow rate detection function. Due to the small size of the selected core sensing element, the power-on preheating is super fast, and preheating, detection and sleep can be completed within 300ms. Low power consumption, suitable for battery power supply. Since there is no material loss like the gas concentration sensor based on the electrochemical principle, the patented product has an ultra-long service life. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:
[0015] Figure 1 This is a schematic diagram of the structure of the analog front end portion of a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip according to an embodiment of the utility model;
[0016] Figure 2 This is a schematic diagram of the structure of the signal processing part of a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip according to an embodiment of the utility model;
[0017] Figure 3 This is a schematic diagram of the data communication structure of a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip according to an embodiment of the utility model;
[0018] Figure 4 This is a schematic diagram of the power supply structure of a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip according to an embodiment of the utility model;
[0019] Figure 5 This is a schematic diagram of a MEMS power supply structure of a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip according to an embodiment of the utility model;
[0020] Figure 6 This is a schematic diagram of a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip according to an embodiment of the utility model. DETAILED DESCRIPTION
[0021] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.
[0022] Reference Figures 1 to 5 ,The utility model discloses a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip, which includes four parts: a sensor analog front-end part, a signal conditioning part, a data processing part, and a power supply part;
[0023] The sensor analog front end part includes a first MEMS chip, which is designed to be open and converts the concentration change of the target gas into a tiny electrical signal according to a linear law, which serves as a signal source for the signal processing part;
[0024] The signal conditioning part includes a second MEMS chip, which is designed to be closed and condition and amplify the tiny electrical signal generated by the analog front end part of the sensor into a low-noise and low-temperature sampling signal;
[0025] The data processing part, including the microcontroller chip, converts the sampled signal into a digital signal and transmits it for communication;
[0026] The power supply part, including the power control chip, provides power supply for the sensor analog front-end part, signal conditioning part, and data processing part.
[0027] Reference Figure 1 and Figure 6 The analog front end of the sensor of a high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip of this embodiment is described as follows:
[0028] The analog front-end part of the high-sensitivity hydrogen concentration sensor based on the thermal conductivity chip of the embodiment of the utility model includes: using an open MEMS chip (i.e., the first MEMS chip) to sense the concentration of hydrogen gas. After a specified voltage is applied between the HEATER1 pin and the HEATER2 pin of the MEMS chip, a stable heat source will be generated between the HEATER1 pin and the HEATER2 pin, and the heat of this heat source will be transferred to other solid surfaces through the gas molecules in the environment. There is a thermocouple between the TH+ pin and the TH- pin of the MEMS chip, and the thermocouple will generate a tiny electrical signal based on the heat transferred by the gas molecules. The higher the concentration of the target gas, the more heat it carries, and the greater the change in the electrical signal AN2 caused. The circuit connection relationship is as follows:
[0029] The second, fifth, fourth, seventh and eighth pins of the first MEMS chip are connected to the ground in parallel; the sixth pin of the first MEMS chip and the sixth pin of the second MEMS chip are connected in parallel to one end of the second resistor; the TH- pin of the first MEMS chip and the TH- pin of the second MEMS chip are connected in parallel; the TH+ pin of the first MEMS chip is connected to the AN2 end of the microcontroller chip; the TH+ pin of the second MEMS chip is connected to the AN3 pin of the microcontroller chip.
[0030] In this embodiment, the model of the first MEMS thermal conductivity chip is selected as: PTCD20-SMD04_MEA.
[0031] Reference Figure 2 and Figure 6 This embodiment describes the signal conditioning part. After the signal of the gas concentration change is obtained from the above analog front end part, the signal conditioning part processes the signal. It can be designed as follows Figure 2 The processing circuit shown uses a sealed MEMS chip (i.e., the second MEMS chip) to seal dry nitrogen with a fixed volume concentration inside the MEMS chip, and the electrical signal AN3 generated by its thermal conductivity is fixed at a constant temperature. AN2 and AN3 form a differential signal input to the ADC interface of the microcontroller chip. The MEMS thermal conductivity chip is connected to the microcontroller (i.e., MCU), and the MCU contains an advanced analog-to-digital conversion (i.e., ADC) function. The ADC inside the microcontroller can perform differential voltage input, small signal amplification and other functions.
[0032] In this embodiment, the MCU also collects the voltage between TH+ and TH- of the second MEMS thermal conductivity chip in real time as a reference standard to improve the detection accuracy.
[0033] The second, fifth, fourth, seventh and eighth pins of the second MEMS chip are connected to the ground in parallel; the sixth pin of the second MEMS chip is connected to one end of the second resistor to provide the required MEMS chip working voltage; the first pin of the second MEMS chip is connected in parallel with the first pin of the first MEMS chip to provide signal input to the microcontroller chip; the third pin of the second MEMS chip provides signal input to the microcontroller chip.
[0034] In this embodiment, the model of the second MEMS thermal conductivity chip is: PTCD20-SMD04S_REF.
[0035] Reference Figure 3 and Figure 6 This embodiment describes the data processing part, which includes a microcontroller chip (i.e., MCU). The microcontroller chip has an analog-to-digital conversion (i.e., ADC) function, and its ADC pin receives a differential signal (AN2, AN3) transmitted from the signal conditioning part.
[0036] In this embodiment, the eighth pin of the microcontroller chip is connected in parallel with the third pin of the first MEMS chip of the signal conditioning part and the AN2 end; the ninth pin of the microcontroller chip is connected in parallel with the third pin of the second MEMS chip of the signal conditioning part and the AN3 end; the third and fourth pins of the microcontroller chip are connected in parallel with one end of the sixth capacitor and one end of the fifth capacitor to ground; the first and second pins of the microcontroller chip are connected in parallel with the other end of the sixth capacitor and one end of the third resistor; the forty-eighth pin of the microcontroller chip is connected in parallel with the other end of the third resistor, the other end of the fifth capacitor, and the VHT end; the forty-seventh pin of the microcontroller is connected to the second pin of the first interface socket, the forty-sixth pin of the microcontroller is connected to the third pin of the first interface socket, and the forty-fifth chip of the microcontroller chip is grounded; the fortieth pin and the thirty-seventh pin of the microcontroller chip are connected to the fourth pin of the second interface socket; the thirty-ninth pin of the microcontroller chip is connected to the third pin of the second interface socket; the thirty-fifth pin of the microcontroller chip is connected in parallel with the I 2C1_SCL and SCL1 ends; the thirty-fifth pin of the microcontroller chip is connected in parallel with the I2C1_SDA and SDA1 ends; the thirty-first pin of the microcontroller chip is connected to I 2C2_SDA is connected; the 30th pin of the microcontroller chip is connected to I2C2_SDL; the 16th pin of the microcontroller chip is connected to the VHT_EN terminal; the 11th pin of the microcontroller chip is connected to the DAC terminal.
[0037] After being processed by the microcontroller chip, the analog signal output by the signal conditioning part is converted into a digital signal, and software filtering, digital gain adjustment, calibration and other processing are performed, and finally the information is sent to the host computer through IIC communication. In this embodiment, a first interface socket and a second interface socket are provided for the host computer to call.
[0038] In this embodiment, the microcontroller model can be selected as: BH66F5250.
[0039] Reference Figure 4 and Figure 6 , the power supply part is illustrated as an example, where VDD is the input power supply, VHT provides the microcontroller chip power supply voltage and ADC sampling bias voltage; GND is the common ground part.
[0040] The power supply part includes a power supply control chip, wherein the first and third pins of the power supply control chip are connected in parallel with one end of the first capacitor, one end of the second capacitor, and the VDD end; the second pin of the power supply control chip is connected in parallel with the other end of the first capacitor and the other end of the second capacitor and is grounded; the fifth pin of the power supply control chip is connected in parallel with one end of the third capacitor, one end of the fourth capacitor, and the VHT end; the other end of the third capacitor and the other end of the fourth capacitor are grounded in parallel.
[0041] Reference Figure 5 The power supply connection for the MEMS chip is as follows: the VHT terminal is connected in parallel with one end of the first resistor and the source of the first field effect tube; the VHT_EN terminal is connected in parallel with the gate of the first field effect tube and the other end of the first resistor; the drain of the first field effect tube is connected to one end of the second resistor; the other end of the second resistor is connected to the HEATER2 pin of the MEMS chip to provide power.
[0042] The microcontroller chip provides power through the MEA terminal.
[0043] In this embodiment, the power control chip model can be selected as TC1055-3.3.
[0044] The hydrogen concentration sensor designed according to the above scheme can be seen through actual testing that this module has a better detection effect on hydrogen concentration, and it is small in size, fast in response, flexible in subsequent data transmission and processing, highly customizable, and can be easily connected to various electronic systems, so that other electronic systems in need can expand the hydrogen concentration detection function. Due to the small size of the selected core sensing element, the startup preheating is super fast, and preheating, detection and sleep can be completed within 300ms. Because there is no material loss like the gas concentration sensor based on the electrochemical principle, this patented product has an ultra-long service life.
[0045] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.
[0046] The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
[0047] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0048] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.
Claims
1. A high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip, characterized in that: include: Sensor analog front-end part, signal conditioning part, data processing part, power supply part; The sensor analog front end part includes a first MEMS chip, which converts the concentration change of the target gas into a tiny electrical signal according to a linear law, which serves as a signal source for the signal processing part; The signal conditioning part includes a second MEMS chip, which conditions and amplifies the tiny electrical signal generated by the analog front end part of the sensor into a sampling signal with low noise and low temperature; The data processing part includes a microcontroller chip, which converts the sampled signal into a digital signal and transmits it through communication; The power supply part provides power supply for the sensor analog front-end part, signal conditioning part and data processing part.
2. The high-sensitivity hydrogen concentration sensor based on the thermal conductivity chip according to claim 1, characterized in that: The sensor analog front end part includes an open first MEMS chip, the second, fifth, fourth, seventh and eighth pins of the first MEMS chip are connected to the ground in parallel; the sixth pin of the first MEMS chip and the sixth pin of the second MEMS chip are connected in parallel to one end of the second resistor; the TH- pin of the first MEMS chip and the TH- pin of the second MEMS chip are connected in parallel; the TH+ pin of the first MEMS chip is connected to the AN2 end of the microcontroller chip; and the TH+ pin of the second MEMS chip is connected to the AN3 pin of the microcontroller chip.
3. The high-sensitivity hydrogen concentration sensor based on thermal conductivity chip according to claim 1, characterized in that: The data conditioning part includes a sealed second MEMS chip, the second, fifth, fourth, seventh and eighth pins of the second MEMS chip are connected to the ground in parallel; the sixth pin of the second MEMS chip is connected to one end of the second resistor to provide the required MEMS chip working voltage; the first pin of the second MEMS chip is connected in parallel with the first pin of the first MEMS chip to provide signal input to the microcontroller chip; the third pin of the second MEMS chip provides signal input to the microcontroller chip.
4. The high-sensitivity hydrogen concentration sensor based on a thermal conductivity chip according to claim 1, characterized in that: The data processing part, the eighth pin of the microcontroller chip is connected in parallel with the third pin of the first MEMS chip and the AN2 end; the ninth pin of the microcontroller chip is connected in parallel with the third pin of the second MEMS chip and the AN3 end; the third and fourth pins of the microcontroller chip are connected in parallel with one end of the sixth capacitor and one end of the fifth capacitor to ground; the first and second pins of the microcontroller chip are connected in parallel with the other end of the sixth capacitor and one end of the third resistor; the forty-eighth pin of the microcontroller chip is connected in parallel with the other end of the third resistor, the other end of the fifth capacitor, and the VHT end; the forty-seventh pin of the microcontroller is connected to the second pin of the first interface socket, the forty-sixth pin of the microcontroller is connected to the third pin of the first interface socket, and the The 45th chip of the microcontroller chip is grounded; the 40th pin and the 37th pin of the microcontroller chip are connected to the fourth pin of the second interface socket; the 39th pin of the microcontroller chip is connected to the third pin of the second interface socket; the 35th pin of the microcontroller chip is connected in parallel with the I2C1_SCL and SCL1 terminals; the 35th pin of the microcontroller chip is connected in parallel with the I2C1_SDA and SDA1 terminals; the 31st pin of the microcontroller chip is connected to I2C2_SDA; the 30th pin of the microcontroller chip is connected to I2C2_SDL; the 16th pin of the microcontroller chip is connected to the VHT_EN terminal; the 11th pin of the microcontroller chip is connected to the DAC terminal.
5. The high-sensitivity hydrogen concentration sensor based on thermal conductivity chip according to claim 1, characterized in that: The power supply part includes a power control chip, the first and third pins of the power control chip are connected in parallel with one end of the first capacitor, one end of the second capacitor, and the VDD end; the second pin of the power control chip is connected in parallel with the other end of the first capacitor and the other end of the second capacitor and is grounded; the fifth pin of the power control chip is connected in parallel with one end of the third capacitor, one end of the fourth capacitor, and the VHT end; the other end of the third capacitor and the other end of the fourth capacitor are grounded in parallel.