Large-scale gas sensor array supporting gas sensitive unit replacement and temperature control programming

Abstract

The invention provides a large-scale gas sensor array supporting gas sensitive unit replacement and temperature control programming, and relates to the field of gas sensors. The large-scale gas sensor array is composed of sensor units made of different materials and with different doping concentrations, high-precision sensing of various gases is achieved, and basic units can be conveniently replaced through the reflow soldering technology. Wherein the heating circuit adopts a programmable circuit design, and independent temperature stability control is carried out on a large number of unit set units. The specific connection structure is as follows: four electrodes of the basic unit structure and a high-level electrode of the heating circuit are connected with nodes of the adjustable resistor and the fixed resistor, a low-level electrode of the heating circuit is grounded, a high-level electrode of the test circuit is connected with GPIO programmable voltage output, and a low-level electrode of the test circuit is connected with ADC output and is grounded through a programmable load resistor. The sensing array has the advantages of high integration, accurate temperature control, programmable adjustment and the like, and can meet various high-precision sensing application requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of gas sensing, and relates to a large-scale gas sensor array supporting gas sensitive unit replacement and temperature control programming. Background Art

[0002] With the increase of environmental pollution, industrial emissions and human activities, the demand for gas detection technology has gradually expanded, especially in the fields of health monitoring, environmental protection, industrial safety, etc. Traditional gas sensors mostly use a single sensing material and often face problems such as slow response, poor selectivity, and poor stability, which limits their wide application. With the advancement of science and technology, the research on multifunctional gas sensor arrays has gradually become a key direction for improving gas detection performance.

[0003] In recent years, gas sensors based on metal oxide semiconductor materials have become a hot topic of research due to their high sensitivity, low cost and easy integration. However, sensors made of a single material often cannot meet the needs of complex gas detection, especially when facing the detection of multi-component gases, where the selectivity and stability of the sensor become bottlenecks. Therefore, the development of integrated, multifunctional, programmable temperature-controlled gas sensor arrays that are easy to replace basic units has become the key to achieving high-performance gas detection. By optimizing the structure and material combination of the array, the response speed, selectivity and stability of the gas sensor can be effectively improved to meet the needs of multi-gas detection.

[0004] In order to solve the above problems, researchers in this field have begun to explore array designs based on a variety of gas sensing materials. By designing sensing units with different materials, different doping types and concentrations, and different operating temperatures, not only can the response characteristics of the sensor be improved, but also a wider range of gas detection functions can be provided under different environmental conditions. At the same time, by introducing programmable temperature control technology in circuit design, the operating temperature of each sensing unit can be independently adjusted, further improving the performance and stability of the sensor.

[0005] However, in the prior art, the design of gas sensor arrays mostly adopts a simple single heating and testing circuit, which makes it difficult to achieve multifunctional and high-precision gas detection. For this reason, referring to the formation of human sense of smell in nature, there are about 4 million olfactory cells in the human nose, of which there are almost 400 types of receptors, but they can identify gas types far exceeding the number of receptors. Referring to the natural background, a new array design scheme is needed that can achieve high-density integration of a large number of gas-sensitive units and efficient data acquisition and processing while ensuring sensor performance, so as to meet the application requirements in complex gas environments.

[0006] Therefore, the present invention proposes a large-scale gas sensor array that supports gas sensitive unit replacement and temperature control programming. By optimizing the design of temperature control heating circuits, signal acquisition circuits and gas sensitive units, a new solution is provided, which can effectively improve the performance of the gas sensor array, especially in multi-gas detection, sensor array integration, low power consumption and high precision. It has important application value. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, the present invention is based on the basic principle of resistive sensor arrays. In order to further expand the application scope of resistive sensor arrays in temperature gradient measurement environments and improve measurement accuracy, a large-scale gas sensor array that supports gas sensitive unit replacement and temperature control programming is proposed. A modular design approach is adopted to divide the array circuit into a temperature control heating circuit, a signal acquisition circuit, a gas sensitive unit and a peripheral functional circuit. It can be used for the precise measurement of gas components by different integrated sensing materials in a temperature gradient measurement environment.

[0008] The present invention is achieved through the following technical solutions:

[0009] A large-scale gas sensor array that supports gas-sensitive unit replacement and temperature control programming:

[0010] The two-dimensional programmable temperature-controlled gas sensor array circuit includes a heating circuit, a test circuit, a temperature gradient gas sensing unit and a peripheral functional circuit;

[0011] Furthermore, the array circuit includes horizontal conductors and vertical conductors to realize array design;

[0012] The temperature gradient gas sensing unit is used to measure gas components and is connected to the heating circuit and the test circuit as a minimum unit;

[0013] The array circuit includes a circuit for realizing a heating function and a circuit for realizing a testing function;

[0014] Furthermore, the temperature gradient gas sensing unit is a four-pin package structure, and the sensing unit can be precisely welded and easily replaced by a reflow soldering method, and the replaceability of the components realizes the versatility of gas component perception;

[0015] Furthermore, the gas sensing material includes different metal oxide semiconductors, such as SnO 2 , ZnO, TiO 2 Etc., and each sensor unit may contain different doped metals such as Pd, Pt, Ru, etc. depending on the type of gas to improve gas selectivity.

[0016] The heating circuit includes a programmable temperature control circuit, and the heating circuit of each gas sensing unit can independently control its operating temperature;

[0017] Furthermore, the high-level electrode of the heating circuit is connected to the node of the adjustable resistor and the fixed resistor, and the low-level electrode is grounded. The resistance gear is switched through multiple MOS tubes to accurately adjust the heating temperature of each sensor unit to ensure that the array sensor works stably within the required temperature range;

[0018] Furthermore, a temperature control mechanism is provided, which can significantly improve the sensitivity and selectivity of the gas sensor array. Through the programmable temperature control design of the heating circuit, the temperature of each sensor unit can be adjusted independently, thereby effectively controlling the sensor's response characteristics to different gases. The control of the temperature gradient not only improves the accuracy of gas detection, but also improves the sensor's selectivity for specific gases, especially in complex gas environments, and can effectively distinguish different gas components.

[0019] The high-level electrode of the test circuit is connected to the programmable GPIO voltage output, and the low-level electrode is connected to the ADC voltage output;

[0020] Furthermore, the test circuit controls the voltage collection of multiple sensor units through time division multiplexing technology, thereby achieving efficient data collection. The test circuit also controls its resistance level through programmable load resistors and MOS tubes to ensure that the parameters of the load resistor can be adjusted according to different detection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the circuit structure of a programmable temperature-controlled 8×8 gas sensor array based on replaceable units proposed by the present invention.

[0022] Figure 2 is an equivalent circuit of a test circuit in an embodiment of the present invention.

[0023] Figure 3 is an equivalent circuit of a heating circuit in an embodiment of the present invention.

[0024] Figure 4 It is the response to 1 ppm acetone at different temperatures in the embodiment of the present invention.

[0025] Figure 5 It is the response to 2 ppm acetaldehyde at different temperatures in the examples of the present invention.

[0026] Figure 6 Schematic diagram of the structure of the gas sensing unit in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0029] In the sensor array of the present invention, the basic unit structure preparation material needs to select different types of gas sensing materials, such as metal oxide semiconductors, such as SnO 2 , ZnO, TiO 2 Etc., the preparation materials should not be considered as limiting the present application.

[0030] like Figure 1 As shown; the present invention proposes a programmable temperature-controlled N×N gas sensor array circuit based on replaceable units, and its single structure is as follows Figure 2 As shown; the two-dimensional resistive gas sensor array includes a heating circuit 1, a temperature gradient gas sensing unit 2 and a test circuit 3;

[0031] like Figure 3 As shown, the test array circuit includes a horizontal wire 5, a vertical wire 7, a sensor unit equivalent gas sensitive resistor 6 and an adjustable gear resistor 8; the MOS tube is selected as the on-off structure of the circuit, which has the advantage of being able to directly program and control the connected resistance gear, making the measurement more accurate and selecting a range suitable for the current resistance value across orders of magnitude.

[0032] like Figure 4 As shown, the heating array circuit includes a horizontal wire 9, a vertical wire 11, a sensor unit equivalent heating voltage pin 10 and an adjustable voltage-dividing resistor 12; the MOS tube is selected as the on-off structure of the circuit, which has the advantage of being able to directly program and control the resistance value of the connected voltage-dividing resistor, thereby controlling the heating voltage and realizing the temperature gradient design in the array.

[0033] In the embodiments of the present invention, by accurately adjusting the operating temperature of each sensor unit, the sensitivity and selectivity of the sensor to different gases can be effectively improved. By adjusting the resistance level of the temperature control circuit, the operating temperature of the sensor can be optimized according to the type of gas, thereby improving the detection sensitivity and selectivity of the gas.

[0034] like Figure 5 and Figure 6 The figure shows the changes in the detection signals of 1ppm acetone and 2ppm acetaldehyde at different temperatures. By controlling the heating circuit to adjust the temperature gradient, high-selectivity and high-precision gas identification can be achieved in a multi-gas environment.

[0035] In an implementation method of an embodiment of the present application, a welding and replacement method of a temperature gradient gas sensor unit is provided, comprising the following steps:

[0036] Step 1, prepare the array circuit board, apply an appropriate amount of solder paste to the electrode position of each four-pin unit by screen printing, and ensure that the surface of the pad is evenly covered with solder paste;

[0037] Step 2: Place the four-pin unit precisely on the pad coated with solder paste, and use automated equipment to align the components to ensure that each pin is in full contact with the pad.

[0038] Step 3, sending the array circuit board into the reflow oven and heating it according to the preset temperature curve; during the heating process, firstly, the temperature of the circuit board is raised to a certain value in the preheating stage, and the solvent in the solder paste begins to evaporate, and then enters the soldering stage, the solder melts and completes the electrical connection between the four-pin unit and the pad;

[0039] Step 4, cooling the soldered circuit board to ensure that the solder solidifies and forms a stable solder joint, completing the soldering of the four-pin unit;

[0040] Step 5: If you need to replace a soldered four-pin unit, heat the old unit to the solder melting temperature using a heating tool or reflow oven to loosen the connection between the original unit and the circuit board;

[0041] Step 6. Use a desoldering machine or desoldering net to remove the solder from the original unit and clean the pads to ensure that there is no residual solder on the pad surface;

[0042] Step 7, accurately place the new four-pin unit on the cleaned pad, re-apply an appropriate amount of solder paste, and send the replaced array circuit board into the reflow oven and heat it according to the same temperature curve to ensure that the new component is firmly connected to the circuit board;

[0043] Step 8: Use automatic optical inspection (AOI) or X-ray inspection to ensure that the solder joints are free of defects and the welding quality is stable. If welding problems are found, local repairs are performed to ensure the electrical performance of each solder joint is stable.

[0044] In an implementation method of the present application, a sensor equivalent resistance measurement method and a heating resistor voltage division method of the array circuit are provided. The principle is to use the voltage division theorem to calculate the voltage flowing through the resistor R iList the corresponding circuit equation for the current.

[0045]

[0046] The voltage divider resistor and gear selection resistor R of the test circuit and heating circuit i All of them can be obtained through the parallel formula of the resistors controlled by three MOS tubes.

[0047]

[0048] By inputting different initial signals into the sensor unit row direction, different measurement values ​​are obtained, thereby listing a group of non-homogeneous linear circuit equations, and the actual potential value at both ends of each resistance unit can be derived.

[0049]

[0050] The above is a detailed introduction to a programmable temperature-controlled 8×8 gas sensor array circuit based on replaceable units proposed in the present invention, and the principles and implementation methods of the present invention are explained. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A large-scale gas sensor array supporting gas-sensitive unit replacement and temperature control programming, characterized in that: It includes an array substrate, a temperature control heating circuit, a signal acquisition circuit, and a gas sensitive unit arranged on the substrate; time division multiplexing technology is used to collect a large number of gas sensitive unit signals and control their operating temperature to form a large-scale gas sensor array; the sensitivity and selectivity to different gases are changed through temperature control programming of the gas sensitive unit to adapt to the application of various scenarios; the integration of the gas sensitive unit adopts a replaceable design, and through the reflow soldering method, not only can the sensitive material thereon be replaced as needed, but also it is convenient to repair local damage to the array.

2. A large-scale gas sensor array supporting gas-sensitive unit replacement and temperature control programming according to claim 1, characterized in that: The array substrate comprises the following materials: Silicon-based materials, PI films or PDMS films are used to carry temperature control heating circuits, signal acquisition circuits, and gas sensing units.

3. A large-scale gas sensor array supporting gas-sensitive unit replacement and temperature control programming according to claim 1, characterized in that: The high-level electrode of the temperature control heating circuit is connected to the node of the adjustable resistor and the fixed resistor, and the low-level electrode is grounded. The temperature control stability of each gas sensing unit is achieved through circuit design.

4. A large-scale gas sensor array supporting gas-sensitive unit replacement and temperature control programming according to claim 1, characterized in that: The high-level electrode of the signal acquisition circuit is connected to the GPIO programmable voltage output, and the low-level electrode is connected to the ADC output and grounded through a programmable load resistor, so as to drive and collect data of each gas sensing unit.

5. A large-scale gas sensor array supporting gas-sensitive unit replacement and temperature control programming according to claim 1, characterized in that: The gas sensing unit includes a supporting layer, a heating layer, an isolation layer, an electrode layer and a sensitive layer. Four electrodes are formed after packaging. The temperature control and heating circuit and the signal acquisition circuit are respectively connected by reflow soldering. The temperature control and heating circuit independently controls the temperature of each gas sensing unit through programmable design. The resistance value change generated by the gas sensing unit is converted into gas-related parameters through the signal acquisition and processing system.

6. A large-scale gas sensor array supporting gas-sensitive unit replacement and temperature control programming according to claim 1, characterized in that: Reflow soldering is completed through the steps of solder paste printing, component placement, reflow heating and solder joint inspection. After the solder paste is applied, the sensor unit is placed and heated through a reflow oven, and the solder melts to connect the electrode and the pad. Finally, automatic optical inspection is used to ensure soldering quality and facilitate component replacement and repair.

7. The temperature control heating circuit according to claim 2, characterized in that: The adjustable resistance type of the test circuit controls the resistance gear through three MOS tubes. The three heating resistors are connected in parallel. When the MOS tube is turned on, it means that the heating resistor of this branch is connected to the circuit. By controlling the on and off of the three resistors, 8 program-controlled resistance gears are obtained, which are connected in series with the fixed resistor to obtain the voltage division of the fixed resistor.

8. The temperature-controlled heating circuit according to claim 3, characterized in that: The temperature control and heating circuit can accurately adjust the operating temperature of each gas sensing unit according to the different types of gases, thereby improving the detection sensitivity and selectivity of the gas sensing unit to the gas, and allowing the entire array to form differential response spectra to different gases.

9. The signal acquisition circuit according to claim 4, characterized in that: The high-level electrode of the test circuit is connected to the GPIO programmable voltage output to meet the needs of time-division multiplexing, and rapid scanning is performed to achieve rapid data collection, saving the reading of gas characteristic resistance line by line. The low-level electrode is connected to the ADC output and grounded through a programmable load resistor. The load resistor is controlled by three MOS tubes, and the three load resistors are connected in parallel. When the MOS tube is turned on, it means that the load resistor of this branch is connected to the circuit. By controlling the on and off of the three resistors, 8 program-controlled resistance gears are obtained, which are connected in series with the gas-sensitive unit to obtain the voltage division when the gas-sensitive unit is measured, which is used to drive and collect data from each gas-sensitive unit.

10. The gas sensing unit according to claim 5, characterized in that: The material used for the sensitive layer in the gas sensing unit is metal oxide semiconductor and its composite material; the gas sensing unit has the characteristics of low power consumption and miniaturization, and is suitable for portable gas detection equipment; the integrated array of gas sensing units can fully identify a single gas and its multi-component mixture.

11. The reflow soldering method according to claim 6, characterized in that: The temperature control accuracy in the reflow soldering process is high, and the heating temperature is controlled between 240°C and 250°C to ensure that the solder is fully melted without damaging the components; during the soldering process, the heating rate and time of the reflow soldering furnace are adjusted according to the needs of the sensor unit to ensure the best soldering effect.

12. The reflow soldering method according to claim 6, characterized in that: Reflow soldering is not only used for initial soldering, but also enables convenient replacement of components. By controlling the temperature during the reflow soldering heating process, the solder can melt to loosen the original soldered sensor unit, making it easy to remove and replace the new component. The high-precision control of reflow soldering enables the replaced component to be stably connected to the array circuit board, ensuring that the quality of the solder joints and the electrical performance are not affected. It is suitable for component replacement and repair in large-scale production.

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