A self-driven multi-component gas sensing system

Abstract

The application discloses a kind of self-driving multi-component gas sensing systems, belong to multi-component gas sensing and self-powered cross application field, comprising: self-powered module includes thermoelectric device, energy storage device, thermal management shell and energy collection circuit;Sensor module includes sensing device and matching sensing circuit;Circuit module includes single-chip microcomputer circuit, single-chip microcomputer circuit is connected with energy collection circuit and sensing circuit respectively;Energy collection circuit stores the electric energy from thermoelectric device into energy storage device, and single-chip microcomputer circuit obtains electric energy from energy storage device, under the control of single-chip microcomputer circuit, sensing circuit cooperates with sensing device to detect multi-component gas, and transmits detection data to single-chip microcomputer circuit, and single-chip microcomputer circuit processes data and stores to data storage medium.The application has the characteristics of self-driving, multi-component, low power consumption and light weight, can meet the demand of long-term independent stable detection of hydrogen and humidity and other multi-component gas in special sealed space.

Description

Technical Field

[0001] This invention relates to the field of multi-component gas sensing and self-powered cross-application, and more specifically, to a self-driven multi-component gas sensing system. Background Technology

[0002] Multi-component gas detection in special sealed spaces is an important branch of the gas sensing field. Compared with open spaces, special sealed spaces place higher demands on sensing systems, mainly including: 1) the inability to rely on external energy sources and the need for self-powering; 2) long-term offline real-time stable detection; 3) the presence of interfering gases; and 4) a wide range of concentration variations.

[0003] Currently, there are two main methods for detecting multi-component gases: designing separate sensor modules or taking samples at regular intervals and then performing offline detection. However, the former is susceptible to cross-sensitivity of multiple gases, while the latter has a time lag, making both unsuitable for applications in special confined spaces, such as inside car engines or aerospace cabins. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a self-driven multi-component gas sensing system, which features self-drive, multi-component, low power consumption and lightweight design, and can meet the needs of long-term independent and stable detection of multi-component gases such as hydrogen and humidity in special sealed spaces.

[0005] The objective of this invention is achieved through the following solution:

[0006] A self-powered multi-component gas sensing system includes a self-powered module, a sensing module, and a circuit module. The self-powered module includes a thermoelectric device, an energy storage device, a thermal management housing, and an energy harvesting circuit. The sensing module includes a sensor and a corresponding sensing circuit. The circuit module includes a microcontroller circuit, which is connected to both the energy harvesting circuit and the sensing circuit. The energy harvesting circuit stores electrical energy from the thermoelectric device in the energy storage device. The microcontroller circuit and the sensing circuit obtain electrical energy from the energy storage device. Under the control of the microcontroller circuit, the sensing circuit, in conjunction with the sensor, detects the multi-component gas and transmits the detection data to the microcontroller circuit. The microcontroller circuit processes the data and stores it in a data storage medium.

[0007] Furthermore, the thermal management housing includes an Al alloy housing, the energy storage device includes a supercapacitor, the data storage medium includes an SD card, the thermoelectric device includes a Bi2Te3-based thermoelectric array, and the sensing module includes a multi-component gas sensor module. The Bi2Te3-based thermoelectric array can convert ambient temperature differences into electrical energy, which is stored in the supercapacitor under the control of the power management chip to power the system. Under the control of the microcontroller circuit, the multi-component gas sensor module detects environmental signals and stores the data in the SD card.

[0008] Furthermore, the thermal management housing is an integrated design to reduce contact thermal resistance and to install fixed components. It uses Al alloy to improve the thermal conductivity of the device while reducing the weight of the device, and designs multiple windows and grooves to improve heat convection efficiency.

[0009] Furthermore, the energy harvesting circuit collects the minute electrical energy generated by the thermoelectric device through an ultra-low power energy management chip and adjusts the chip's output voltage and the threshold voltage of related devices to power the microcontroller circuit and sensor circuit; the microcontroller circuit controls the opening or closing of the sensor circuit and the process of reading data from the SD card through two electronic switches, thereby achieving lower power consumption.

[0010] Furthermore, the sensor circuit includes a hydrogen sensing circuit and a humidity sensing circuit composed of a Wheatstone bridge circuit and a differential operational amplifier circuit, used to detect and process relevant signals.

[0011] Furthermore, the thermoelectric device is encapsulated using an aluminum heat sink with windows and heat dissipation fins.

[0012] Furthermore, the microcontroller circuit is responsible for controlling the opening and closing of the sensing circuit, and for acquiring sensor signals, converting analog signals into digital signals, and processing and storing them.

[0013] Furthermore, the sensor components in the multi-component gas sensor module include a hydrogen sensor and a humidity sensor.

[0014] Furthermore, the power management chip includes the BQ25570 chip.

[0015] Furthermore, the hydrogen-sensitive material of the hydrogen sensor is a patterned PdAu-based hydrogen-sensitive material prepared by magnetron sputtering, and the humidity-sensitive material of the humidity sensor is a graphene material prepared by laser direct writing technology.

[0016] The beneficial effects of this invention include:

[0017] This invention is particularly applicable to special sealed spaces, and proposes a sensing system involving the acquisition of energy from thermoelectric devices and the detection of multi-component gases in the environment, with the following technical specifications: the operating power of the embodiments of this invention is no higher than 640 μW, and the effective volume (excluding the Al alloy shell) is less than 50 cm³. 3 The effective mass (excluding the Al alloy shell) can be less than 50g. The system can maintain normal operation under temperature differences greater than 9.5K. The hydrogen sensing module has a detection limit better than 10ppm, a detection accuracy of 2%FS, and an operating power of approximately 10mW. The humidity sensing module features a wide detection range (10ppm-65%), a low detection limit (10ppm), fast response (<1min@1vt.% hydrogen), and low power consumption (mW level). Thanks to the low leakage current and large capacity of the supercapacitor, as well as the low-power circuit design, this invention exhibits long-term stability and strong resilience. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structural composition of the self-driven multi-component gas sensing system according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the temperature difference of the thermoelectric device according to an embodiment of the present invention;

[0021] Figure 3 This is a model diagram of the thermal management housing according to an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram illustrating the working principle of the circuit module in an embodiment of the present invention;

[0023] Figure 5 This is a circuit diagram of the energy harvesting circuit according to an embodiment of the present invention;

[0024] Figure 6 This is a circuit diagram of the microcontroller circuit and peripheral circuits according to an embodiment of the present invention;

[0025] Figure 7 This is a circuit diagram of the electronic switch according to an embodiment of the present invention.

[0026] Figure 8 This is a circuit diagram of the humidity sensor circuit according to an embodiment of the present invention;

[0027] Figure 9 This is a circuit diagram of the hydrogen sensor circuit according to an embodiment of the present invention;

[0028] Figure 10 This is a test diagram of the output performance of the thermoelectric device according to an embodiment of the present invention;

[0029] Figure 11 These are the charge and discharge curves of the supercapacitor during operation according to an embodiment of the present invention;

[0030] Figure 12 This is a hydrogen sensitivity test curve diagram of an embodiment of the present invention;

[0031] Figure 13 This is a humidity-sensitive test curve diagram of an embodiment of the present invention. Detailed Implementation

[0032] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0033] In view of the problems mentioned in the background, the inventors of this invention, after creative thinking, believe that, based on the reasons described in the background art, this invention addresses the technical problems by adopting an internally integrated sensor group to automatically detect multi-component concentration signals. Specifically, firstly, this invention utilizes thermoelectric energy for power generation. Compared to solar power generation and wind power generation, thermoelectric power generation is less constrained by weather factors and is more suitable for special sealed spaces. Secondly, this invention optimizes the performance of thermoelectric devices to match energy supply requirements, thereby achieving heat recovery from low-density heat sources. Then, based on improving the energy conversion efficiency of the devices, it completes system thermoelectric management and the collection of minute amounts of energy. Considering that the system's power consumption mainly comes from energy loss during the collection of minute amounts of energy and energy consumption during the sensor circuit's signal detection and acquisition process, this invention reduces power loss from both the energy collection circuit and the sensing circuit. Finally, this invention integrates various types of gas-sensitive devices into the sensing circuit, and uses a microcontroller circuit to control the sensing circuit to collect and process environmental signals, storing the final results on an SD card. In summary, the embodiments of the present invention utilize thermal temperature difference energy to generate electricity. Based on the optimization of micro-energy harvesting and sensor signal acquisition, the gas sensing system realized is of great significance for the long-term stable detection of multi-component gases in special sealed spaces.

[0034] like Figure 1As shown, the sensing system of this embodiment includes three modules: a self-powered module, a circuit module, and a sensing module. The self-powered module includes a thermoelectric device, an energy storage device, a thermal management housing, and an energy harvesting circuit. The main body of the thermoelectric device is a Bi₂Te₃-based thermoelectric generator. The energy storage device uses a supercapacitor, which has advantages such as low leakage current, high output power, and a wide operating temperature range, making it suitable for long-term offline independent operation. For thermal management, methods such as heat sinks, heat pipes, and radiative cooling can be adopted. Considering the high heat transfer efficiency of heat sink encapsulation and the ease of internal component integration, the system of this embodiment uses a heat sink. For materials, copper alloys and aluminum alloys can be selected. Considering that aluminum alloys are beneficial for reducing system weight, the system of this embodiment uses an aluminum alloy housing. The energy harvesting circuit stores the electrical energy of the thermoelectric device in the supercapacitor to supply the circuit module and the sensing module. Then there is the circuit module, which mainly consists of the energy harvesting circuit, a microcontroller circuit, and the sensing circuit. The energy harvesting circuit is independent of the latter two; it collects and stores the small electrical energy from the thermoelectric device through a low-power energy management chip. The microcontroller circuit and the sensing circuit work together. The microcontroller circuit controls the switching on and off of the sensing circuit, the measurement cycle, data processing, and storage, while the sensor circuit digitizes and amplifies the analog signals from the sensor device. The sensing module mainly consists of a sensing circuit and sensor devices. In the system of this embodiment, the sensor devices used refer to a PdAu-based hydrogen sensor and a graphene humidity sensor.

[0035] Figure 3 The thermal management housing designed for the system in this embodiment of the invention features an integrated design to reduce contact thermal resistance and includes fixed components. The overall dimensions are 74×74×50mm. 3 (Excluding the top surface and screws). Each side has multiple U-shaped grooves and rectangular openings to promote heat convection between the system's interior and exterior environments, thereby improving the utilization efficiency of ambient temperature differences. The entire housing is secured to the exterior environment by four spring-loaded screws.

[0036] Figure 4 The diagram illustrates the relationship between different circuit modules. The energy harvesting circuit stores electrical energy from thermoelectric devices into a supercapacitor. The microcontroller circuit and sensing circuit extract electrical energy from the supercapacitor. Under the control of the microcontroller circuit, the sensing circuit, in conjunction with sensor devices, detects multi-component gases and transmits the detection data to the microcontroller circuit. The microcontroller circuit processes the data and stores it on an SD card.

[0037] like Figure 5As shown, the power management chip used in the energy harvesting circuit is the BQ25570. This chip has ultra-low power consumption characteristics and can harvest energy as low as 10mW, making it very suitable for energy harvesting from thermoelectric generators. In the system of this embodiment, the negative terminal of the thermoelectric generator is grounded, and the positive terminal SOLAR+ port is connected to pins 2 and 20 of the power management chip, where pin 20 is also connected to inductor L1. The positive terminal of the supercapacitor is directly connected to the VBAT pin, and the negative terminal is grounded. Pin 16 is connected to pin 14 through inductor L2, and the microcontroller circuit is connected to the connection point between pins 14 and 16. In addition, the programmable impedance network composed of resistors connected to pins 8, 7, 11, 10, and 12 can adjust the charging threshold of the supercapacitor (i.e., the output threshold of the VBAT pin, which is 5.5V in this system) and the output voltage of the cross pin between pins 16 and 14 (this output voltage is fixed at VCC3.3 in this system, which is the operating voltage of the microcontroller circuit, 3.3V).

[0038] like Figure 6 As shown, the microcontroller circuit controls the timing, sampling, data processing, and storage of the sensing circuit. Specifically, the microcontroller's ADC acquires the voltage signal output from the hydrogen sensing circuit via pin PA5, and acquires the voltage signal output from the humidity sensing circuit via pins PA1 and PA2. Crystal oscillator X1 is connected to pins 5 and 6 of the microcontroller, providing a clock signal for its operation; crystal oscillator 2 is connected to pins 3 and 4 of the microcontroller, providing a clock signal for the RTC circuit. This embodiment of the invention can acquire the supercapacitor's charge data and dynamically adjust the microcontroller circuit's startup time based on the charge level, i.e., adjust the sensing circuit's sampling time and frequency. Microswitch SW1 is used for microcontroller reset. The microcontroller's power supply connection is shown in section U1B, where the VBAT pin is connected to a capacitor configured on the microcontroller itself as a backup power supply. Capacitors C6, C7, C8, and C9 are connected to the main power supply VCC3.3 and ground for filtering.

[0039] like Figure 7 As shown, the system in this embodiment of the invention uses two electronic switches, U2 and U3, which are connected to the microcontroller's PB11 and PB9 pins respectively and communicate with the microcontroller via the SPI protocol. A 3.3V voltage is output from pin 1 of the switch circuit. U2 controls the power supply to the sensing circuit, and U3 controls the power supply to the SD circuit. The microcontroller circuit controls the switching of the sensing circuit through the electronic switch circuit; that is, the sensor circuit is turned on during measurement and turned off at other times, thereby reducing system power consumption.

[0040] like Figure 8As shown, the humidity sensor Cap Var, along with resistors R21, R23, and R22, forms an excitation circuit. The microcontroller circuit acquires the voltage levels across R22 via pins PA1 and PA2 to calculate humidity information. The differential operation circuit U6 enhances the load-carrying capacity of the square wave signal. This square wave signal refers to a set of complementary PWM square waves input to U6 via pins PA8 and PA7. U6 performs a subtraction operation on this complementary square wave and transmits the data to R23 and R22 via pins 4 and 5 to excite the humidity sensor Cap Var.

[0041] like Figure 9 As shown, the hydrogen sensor R5 is integrated into a Wheatstone bridge. The bridge output signal is amplified by operational amplifier U5, with the amplification factor controlled by resistor RG. The amplified signal is then processed by a differential amplifier circuit, which acts as a voltage follower, causing a shift in the overall output voltage of the sensor circuit, thus providing a good dynamic detection range. Finally, the hydrogen sensor signal is output from pin 7 through resistor R11 to the PA5 port of the microcontroller.

[0042] First, combine Figure 2 and Figure 3 The first embodiment will be described. In this embodiment, Bi2Te3-based particles are soldered onto an AlN copper-clad substrate using Sn paste and connected to an energy harvesting circuit via wires. The output voltage of the thermoelectric device depends primarily on the temperature difference between the bottom of the housing and the system interior, specifically the temperature difference ΔT between the bottom and top of the thermoelectric array, rather than the temperature difference ΔT0 between the bottom of the thermoelectric array and the interior of the cavity. Thermal management is necessary to achieve higher output power for the thermoelectric array. Testing has shown that... Figure 3 With the assistance of the thermal management housing shown, when ΔT0 is 9.5K, ΔT can reach 1.07K, and the effective utilization rate of the temperature difference is about 11.26%. At this time, the output voltage of the thermoelectric device is 144.07mV, and the maximum output power is 535μW.

[0043] Then combine Figure 11 The second embodiment will be described. The fabrication process of the pn junction array of Bi2Te3-based material used in the system of this embodiment is as follows: (1) cutting the Bi2Te3-based ingot into circular wafers; (2) electroplating a Ni transition layer and a Sn bonding layer; (3) cutting the wafers into 0.9×0.9×2mm pieces. 3 (4) P / N type material particles are arranged alternately and evenly, with their positions matching the copper-clad circuit board; (5) screen printing solder and reflow soldering; (6) insulating encapsulation. Finally, the encapsulated thermoelectric array is fixed inside the thermal management housing, and the housing is placed on the heating platform. The temperature difference between the two ends of the thermoelectric array is adjusted by adjusting the temperature of the heating platform. The performance test results obtained are as follows: Figure 11As shown in the figure. The device corresponding to curve #3 is currently used in the system. This thermoelectric device mainly consists of 338 pairs of Bi2Te3-based pn structures connected in series. Testing showed that when the ambient temperature difference ΔT reaches 13K, the output voltage is 1.6V and the output power is 57.4mW; when the effective temperature difference ΔT0 is greater than 1.4K, the system can maintain normal operation.

[0044] Then combine Figure 12 The third embodiment will be described. Figure 12 The diagram illustrates the voltage of the supercapacitor and the output voltage of the thermoelectric device during system operation. With the ambient temperature difference across the thermoelectric device controlled at 10K (0-1500s) and 9.5K (1500-3800s), the supercapacitor voltage continuously increases, indicating that, while ensuring normal system operation, excess electrical energy is collected by the supercapacitor through the energy harvesting circuit (the system in this embodiment detects ambient gas every hour, and correspondingly, the supercapacitor voltage decreases every hour). After 3800s, with the ambient temperature difference controlled at 8.5K, the thermoelectric device's output capacity decreases, and the supercapacitor voltage curve declines over time, indicating that the electrical energy generated by the thermoelectric device alone is insufficient to maintain normal system operation, necessitating the consumption of the supercapacitor's electrical energy.

[0045] Then combine Figure 13 The fourth embodiment is described below. The testing procedure for H2 in this embodiment is as follows: The sensing system is placed in the test chamber, and 4% volume fraction H2 and argon are alternately passed through four or more times to stabilize the internal structure of the hydrogen-sensitive material and the voltage baseline. Then, a H2 / Ar mixture with a volume fraction of 5ppm-4% is passed through from low to high, with each concentration tested for one day. Finally, Ar is passed through for recovery. The test results show that the system's detection limit is not lower than 5ppm, the response / recovery speed is fast, the response is stable, and the stability is also relatively good.

[0046] Finally, the fifth embodiment will be described. Similar to the H2 sensitivity test, the sensing system placed in the test chamber was first aged to stabilize the internal structure of the humidity-sensitive material. Then, the system was purged with argon gas at different humidity levels, from low to high. To verify the reliability of this humidity sensing module, a standard humidity sensor was also used during the test. The test results show that this humidity sensing module has a wide test range, fast detection time (<1 min), and good stability.

[0047] The units described in the embodiments of the present invention can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the specific unit itself.

Claims

1. A self-driven multi-component gas sensing system, characterized in that, It includes a self-powered module, a sensing module, and a circuit module; The self-powered module includes a thermoelectric device, an energy storage device, a thermal management housing, and an energy harvesting circuit; the sensing module includes a sensor and a matching sensing circuit; the circuit module includes a microcontroller circuit, which is connected to both the energy harvesting circuit and the sensing circuit. The energy harvesting circuit stores electrical energy from the thermoelectric device into the energy storage device. The microcontroller circuit and the sensing circuit obtain electrical energy from the energy storage device. Under the control of the microcontroller circuit, the sensing circuit works with the sensor device to detect multi-component gas and transmits the detection data to the microcontroller circuit. The microcontroller circuit processes the data and stores it in the data storage medium. The energy harvesting circuit collects the minute electrical energy generated by the thermoelectric device through an ultra-low power energy management chip and adjusts the chip's output voltage and the threshold voltage of related devices to power the microcontroller circuit and sensor circuit; the microcontroller circuit uses two electronic switches to control the opening or closing of the sensor circuit and the process of reading data from the SD card, thereby achieving lower power consumption. The sensor circuit includes a hydrogen sensing circuit and a humidity sensing circuit composed of a Wheatstone bridge circuit and a differential operational amplifier circuit, used to detect and process relevant signals. The thermoelectric device is encapsulated using an aluminum heat sink with windows and heat dissipation fins.

2. The self-driven multi-component gas sensing system according to claim 1, characterized in that, The thermal management housing includes an Al alloy housing, the energy storage device includes a supercapacitor, the data storage medium includes an SD card, the thermoelectric device includes a Bi2Te3-based thermoelectric array, and the sensing module includes a multi-component gas sensor module. The Bi2Te3-based thermoelectric array converts ambient temperature difference energy into electrical energy, which is stored in the supercapacitor under the control of the power management chip to power the system. Under the control of the microcontroller circuit, the multi-component gas sensor module detects environmental signals and stores the data in the SD card.

3. The self-driven multi-component gas sensing system according to claim 1, characterized in that, The thermal management housing is an integrated design to reduce contact thermal resistance and to install fixed components. It uses Al alloy to improve the thermal conductivity of the device while reducing the weight of the device, and it is designed with multiple windows and grooves to improve heat convection efficiency.

4. The self-driven multi-component gas sensing system according to claim 1, characterized in that, The microcontroller circuit is responsible for controlling the opening and closing of the sensing circuit, acquiring sensor signals, converting analog signals into digital signals, and processing and storing them.

5. The self-driven multi-component gas sensing system according to claim 2, characterized in that, The sensors in the multi-component gas sensor module include a hydrogen sensor and a humidity sensor.

6. The self-driven multi-component gas sensing system according to claim 2, characterized in that, The power management chip includes the BQ25570 chip.

7. The self-driven multi-component gas sensing system according to claim 5, characterized in that, The hydrogen-sensitive material of the hydrogen sensor is a patterned PdAu-based hydrogen-sensitive material prepared by magnetron sputtering, and the humidity-sensitive material of the humidity sensor is a graphene material prepared by laser direct writing technology.

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