MEMS thermal conductivity detector structure applied to GC

Abstract

The utility model discloses an MEMS (Micro Electro Mechanical System) thermal conductivity detector structure applied to GC (Gas Chromatography). The MEMS thermal conductivity detector structure comprises a detector structure body, a detection circuit board and an MEMS sensor, the detection circuit board is arranged at the top of the detector structure body; an MEMS sensor is electrically connected and fixed below the detection circuit board; a detection pool is arranged below the MEMS sensor; an air inlet and an air outlet are respectively formed in different side walls of the detector structural body; the air inlet is communicated through a first air path arranged in the detector structure body; the air outlet is communicated through a second air path arranged in the detector structure body; the first gas path is communicated with the second gas path through the detection pool. The gas circuit is compact in design, a gas sample and the sensor can be promoted to be fully contacted at a detection pool, and accurate heat exchange and quick response of the sensor are ensured; the concentration of a specific component in a gas sample can be judged by introducing gases with different heat conductivities to cause the resistance change of a thermistor on the MEMS sensor, so that efficient and accurate gas detection is realized.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of heat conduction gas detection, especially relate to a MEMS heat conduction detector structure for GC. BACKGROUND

[0002] With the continuous progress of science and technology, in the field of gas analysis and detection, the demand for efficient, accurate and reliable gas detector is increasingly urgent. In the traditional gas analysis and detection method, the most commonly used method is gas chromatography GC, that is, the chromatography method using gas as mobile phase. Gas chromatography is a powerful analytical technique that can be used to separate, identify and quantify individual chemical components in complex mixtures. In gas chromatography (GC) and other applications, the performance requirements for flow-through gas detectors are relatively stringent. Traditional gas detectors are often heat conduction gas analyzers, which mainly measure the thermal conductivity of mixed gas to analyze the concentration of the component to be measured. The heat conduction gas analyzer has many deficiencies in the low range, and cannot detect trace components, mainly because the detection sensitivity of the sensor is low and is greatly affected by the background gas.

[0003] Therefore, the conventional gas detector has the problem of low detection result accuracy due to low sensitivity and poor stability. SUMMARY

[0004] In view of the above problems, it is necessary to provide a MEMS heat conduction detector structure for GC, which is convenient to use and has high detection accuracy.

[0005] A MEMS heat conduction detector structure for GC, comprising: a detector structure body, a detection circuit board and a MEMS sensor; wherein:

[0006] The detection circuit board is arranged on the top of the detector structure body; the MEMS sensor is electrically connected and fixed below the detection circuit board; a detection cell is arranged below the MEMS sensor; gas inlets and outlets are arranged on different side walls of the detector structure body, and the gas inlets and outlets are in communication with the detection cell;

[0007] The gas inlets are communicated through a first gas path arranged in the detector structure body; the gas outlets are communicated through a second gas path arranged in the detector structure body; the first gas path and the second gas path are communicated through the detection cell;

[0008] The gas to be detected is input from the gas inlet and transmitted to the detection cell position to contact the MEMS sensor, and the MEMS sensor is used to monitor the thermal conductivity change data of the gas to be detected when passing through; the detection circuit board is used to calculate the concentration of the target gas in the gas to be detected according to the thermal conductivity change data.

[0009] In one embodiment, the gas inlet is arranged on a first sidewall of the detector structure, and the gas outlet is arranged on a second sidewall of the detector structure; the first sidewall is arranged opposite to the second sidewall, and the gas inlet and the gas outlet are in a collinear position.

[0010] In one embodiment, the gas inlet is parallel to the surface of the MEMS sensor.

[0011] In one embodiment, the gas inlet is arranged on a bottom of the detector structure, and the gas outlet is arranged on a sidewall of the detector structure; the bottom is arranged perpendicular to the sidewall.

[0012] In one embodiment, the gas inlet is perpendicular to the surface of the MEMS sensor.

[0013] In one embodiment, the detection cell is in a trapezoidal cylindrical structure, and the distance between the bottom surface of the detection cell and the surface of the MEMS sensor is 1.8mm to 2mm.

[0014] In one embodiment, the diameter of the top of the detection cell is 0.15mm to 0.25mm larger than the diameter of the surface of the MEMS sensor.

[0015] In one embodiment, the diameter of the gas inlet and the gas outlet is 0.6mm to 1.7mm.

[0016] In one embodiment, a ferrule joint is arranged on the gas inlet and the gas outlet, and the ferrule joint is used to connect with an external pipeline.

[0017] The above-mentioned MEMS thermal conductivity detector structure applied to GC, by arranging the MEMS sensor above the detection cell, arranging the gas inlet and the gas outlet on different sidewalls of the detector structure respectively, and connecting the two gas paths through the detection cell, the compact gas path design can promote the full contact of the gas sample and the sensor at the detection cell, reduce the dead volume in the cavity, thereby ensuring accurate heat exchange and fast response of the sensor; by controlling the MEMS sensor through the detection circuit board, observing the resistance value change of the thermistor on the MEMS sensor can accurately judge the concentration of the specific component in the gas sample, realize efficient and accurate gas detection, and provide reliable hardware support for the field of gas analysis and detection. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a structural diagram of a MEMS thermal conductivity detector structure applied to GC in one embodiment;

[0019] Figure 2 FIG. 2 is a structural diagram of a MEMS thermal conductivity detector structure applied to GC in another embodiment; Figure 1A schematic view of the relative position of the gas inlet 110 and the MEMS sensor 300 in the structure shown.

[0020] Figure 3 A structural diagram of a MEMS thermal conductivity detector structure applied to GC in another embodiment;

[0021] Figure 4 For Figure 3 A schematic view of the relative position of the gas inlet 110 and the MEMS sensor 300 in the structure shown. DETAILED DESCRIPTION

[0022] In order to better understand the present application, the content of the present application will be further illustrated below in combination with the drawings and embodiments, but the present application is not limited to only the following embodiments.

[0023] In one embodiment, as Figure 1 shown, the present application provides a MEMS thermal conductivity detector structure applied to GC, mainly comprising: a detector structure body 100, a detection circuit board 200, a MEMS sensor 300; wherein:

[0024] The detection circuit board 200 is arranged at the top of the detector structure body 100; the MEMS sensor 300 is electrically connected and fixed below the detection circuit board 200; the detection cell 400 is arranged below the MEMS sensor 300; the gas inlet 110 and the gas outlet 120 are arranged on different side walls of the detector structure body 100, and the gas inlet 110 and the gas outlet 120 are both in communication with the detection cell 400;

[0025] The gas inlet 110 is communicated through the first gas path 112 arranged in the detector structure body 100; the gas outlet 120 is communicated through the second gas path 122 arranged in the detector structure body 100; the first gas path 112 and the second gas path 122 are communicated through the detection cell 400;

[0026] The gas to be detected is input from the gas inlet 110 and transmitted to the detection cell 400 position to contact the MEMS sensor 300, and the MEMS sensor 300 is used to monitor the thermal conductivity change data when the gas to be detected passes; the detection circuit board 200 is used to calculate the concentration of the target gas in the gas to be detected according to the thermal conductivity change data.

[0027] Among them, the detector structure body 100 can be a container for detecting the concentration of gas, in this embodiment, the shape of the detector structure body 100 can be a rectangular body, and it can also be other regular or irregular polyhedrons, which is convenient for detecting the concentration of gas.

[0028] The detection circuit board 200 can be arranged on the top of the detector structure 100, and plays a detection control role for the whole MEMS thermal conductivity detector structure. The detection circuit board 200 can be an integrated circuit board, which is used to realize functions such as gas detection and gas concentration calculation.

[0029] As shown in Figure 1 The MEMS sensor 300 is arranged below the detection circuit board 200 and is electrically connected with the detection circuit board 200, and is used to collect the thermal conductivity change data of the gas sample when passing through the detection cell. Specifically, the MEMS sensor 300 is precisely arranged to monitor the thermal conductivity change when the gas sample passes through; the heat exchange between the MEMS sensor 300 and the gas sample is the basis for realizing the detection of the gas component, and by precisely controlling the temperature of the MEMS sensor 300 and observing the thermal conductivity change, the concentration of the specific component in the gas sample can be accurately judged.

[0030] The detection cell 400 can be arranged below the MEMS sensor 300, and the gas sample contacts the MEMS sensor 300 when passing through the detection cell 400, and the thermal conductivity change data is collected by the MEMS sensor 300, and then transmitted to the detection circuit board 200 for specific component concentration calculation.

[0031] The gas inlet 110 is arranged on the side wall of the detector structure 100, facilitating the gas sample to enter; the gas outlet 120 is arranged on the other side wall of the detector structure 100, facilitating the gas sample to be discharged. The gas inlet 110 and the gas outlet 120 are both in communication with the detection cell 400, that is, after the gas sample enters from the gas inlet 110, it is guided to the position of the detection cell 400, contacts the MEMS sensor 300 and is collected information, and after passing through the detection cell 400, the gas sample flows to the gas outlet 120 and is discharged from the detector structure 100.

[0032] In this embodiment, the transmission channel connecting the gas inlet 110 and the detection cell 400 is taken as the first gas path 112, and the transmission channel connecting the gas outlet 120 and the detection cell 400 is taken as the second gas path 122, and the first gas path 112 and the second gas path 122 are in communication through the detection cell 400.

[0033] In the conventional design of the gas path of the MEMS thermal conductivity detector, a branch gas path is often designed on the main gas path, and the diameter of the branch gas path is only 0.2 to 0.5 times that of the main gas path. The detection cell of the MEMS sensor is designed on the branch flow path. Since the diameter of the main gas path is much larger than that of the branch gas path, the gas mainly flows through the main gas path, and the change of the gas concentration in the branch path depends entirely on the diffusion of molecules, that is, the molecules in the high concentration region diffuse to the low concentration region, so that the air exchange of the detection cell is slow, the heat exchange speed is also slow, and the response time of the sensor is increased and the sensitivity of the sensor is reduced. Such a TCD detector is not suitable for gas chromatography.

[0034] In the embodiment, by arranging the MEMS sensor 300 above the detection cell 400, arranging the gas inlet 110 and the gas outlet 120 on different side walls of the detector structure 100 respectively, and connecting the two gas paths through the detection cell 400, the gas path design is compact, which can promote the full contact of the gas sample and the sensor at the detection cell 400, reduce the dead volume in the cavity, thereby ensuring accurate heat exchange and fast response of the sensor; by controlling the MEMS sensor 300 through the detection circuit board 200, observing the change of thermal conductivity can accurately judge the concentration of a specific component in the gas sample, realize efficient and accurate gas detection, and provide reliable hardware support for the field of gas analysis and detection.

[0035] In one embodiment, as shown in Figure 1 , the gas inlet 110 is arranged on the first side wall 101 of the detector structure 100, and the gas outlet 120 is arranged on the second side wall 102 of the detector structure 100; the first side wall 101 and the second side wall 102 are arranged opposite to each other, and the gas inlet 110 and the gas outlet 120 are in a collinear position.

[0036] The gas inlet 110 and the gas outlet 120 are arranged in a collinear position, so that the gas sample has only one path from the gas inlet 110 to the gas outlet 120.

[0037] As shown in Figure 2 , in one embodiment, the gas inlet 110 is parallel to the surface of the MEMS sensor 300, when there is a difference in gas concentration, not only can the exchange be carried out by diffusion, but also the detection cell gas can be replaced by the flow of the gas.

[0038] In one embodiment, as shown in Figure 3 , the gas inlet 110 is arranged at the bottom of the detector structure 100, and the gas outlet 120 is arranged on the side wall of the detector structure 100; the bottom and the side wall are arranged vertically.

[0039] As shown in Figure 4 , the gas inlet 110 is perpendicular to the surface of the MEMS sensor 300. Since the gas inlet 110 of the gas path is located at the bottom of the detector structure 100 and is perpendicular to the surface of the MEMS sensor 300, to ensure that the detected gas reaches the surface of the MEMS sensor 300 quickly, uniformly and stably.

[0040] As shown in Figure 3 , after passing through the detection cell 400, the gas sample will flow smoothly to the gas outlet 120 and be discharged from the detector structure 100. The outlet design ensures the continuity of the gas flow, avoiding possible blockage or backflow.

[0041] Specifically, in one embodiment, the detection pool is in a trapezoidal cylindrical structure, and the distance between the bottom surface of the detection pool and the surface of the MEMS sensor is 1.8 mm to 2 mm. The diameter of the top of the detection pool is 0.15 mm to 0.25 mm larger than the diameter of the surface of the MEMS sensor.

[0042] In the present embodiment, once the gas sample enters the detector, it is guided to the core detection pool area. The design of the detection pool fully considers the interaction between the gas sample and the MEMS sensor. The detection pool has an optimized geometry and size. Specifically, the detection pool is in a trapezoidal cylindrical design, which is large at the top and small at the bottom. The height of the surface of the MEMS sensor and the bottom surface of the cylinder is between 1.8 mm and 2 mm. The diameter of the upper end of the trapezoidal cylinder is about 0.2 mm larger than the diameter of the surface of the MEMS sensor. This size is designed to promote sufficient contact between the gas sample and the MEMS sensor and to minimize the dead volume in the cavity, thereby ensuring accurate heat exchange and fast response of the sensor.

[0043] In one embodiment, the diameter of the gas inlet and the gas outlet is 0.6 mm to 1.7 mm. Specifically, the pipe diameter of the gas inlet and the gas outlet requires Φ1 / 32 to Φ1 / 16. The thinner the pipe diameter, the faster the flow rate of the sample gas being detected under the same flow rate, the greater the temperature change of the surface of the MEMS sensor, and the greater the resistance change, thereby improving the sensitivity of the sensor. Among them, Φ1 / 32 represents a diameter of 1 / 32 inch, and 1 inch is equal to 25.4 mm.

[0044] As shown in Figure 1 , Figure 3 , the gas inlet 110 and the gas outlet 120 are each provided with a ferrule joint 130 for connecting with external pipelines.

[0045] The ferrule joint provided at the gas inlet 110 is further connected with the gas inlet pipe, and the ferrule joint provided at the gas outlet 120 is further connected with the gas outlet pipe, thereby facilitating complete gas sample inlet and outlet. In the present embodiment, the ferrule joint 130 can be composed of a joint body, a ferrule, and a nut. The pipe diameter size at the ferrule joint 130 is larger than the pipe diameter size at the gas inlet 110 and the gas outlet 120. When the gas sample flows from the ferrule joint 130 to the gas inlet 110, the pipe diameter size changes, which can increase the gas pressure, accelerate the detection speed, and reduce the dead volume.

[0046] The MEMS thermal conductivity detector structure applied to GC provided by the application pays attention to the sealing and durability of the whole gas path design. High-quality materials and processes are used for all connection parts and interfaces to ensure the tightness and long-term stability of the gas path; in addition, anticorrosion and high-temperature-resistant materials are used inside the gas path to adapt to the needs of different gas samples and working environments. The gas path design can realize efficient and accurate gas detection through a compact flow-through structure and an optimized detection cell design, thereby providing reliable hardware support for the field of gas analysis and detection.

[0047] The use method of the MEMS thermal conductivity detector structure applied to GC provided by the application is as follows:

[0048] The gas sample enters the first gas path from the gas inlet through the gas inlet pipe and reaches the detection cell position through the first gas path;

[0049] The gas sample interacts with the MEMS sensor at the detection cell position, and the MEMS sensor collects the thermal conductivity change in real time and sends it to the detection circuit board;

[0050] The detection circuit board accurately judges the concentration of the specific component in the gas sample;

[0051] After the gas sample passes through the detection cell, it flows to the gas outlet through the second gas path and is discharged through the gas outlet pipe.

[0052] The technical features of the above embodiments can be combined arbitrarily, and to make the description concise, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0053] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A MEMS thermal conductivity detector structure applied to a GC, characterized in that, The application relates to a detector structure, a detection circuit board and a MEMS sensor. The detection circuit board is arranged on the top of the detector structure, and the MEMS sensor is electrically connected and fixed below the detection circuit board; a detection pool is arranged below the MEMS sensor; an air inlet and an air outlet are arranged on different side walls of the detector structure respectively, and the air inlet and the air outlet are communicated with the detection pool; The air inlet is communicated through a first air path arranged in the detector structure; the air outlet is communicated through a second air path arranged in the detector structure; the first air path and the second air path are communicated through the detection pool; The to-be-detected gas is input from the air inlet and transmitted to the detection pool to contact the MEMS sensor, and the MEMS sensor is used for monitoring the thermal conductivity change data of the to-be-detected gas; the detection circuit board is used for calculating the concentration of a target gas in the to-be-detected gas according to the thermal conductivity change data. The air inlet is arranged on the first side wall of the detector structure, and the air outlet is arranged on the second side wall of the detector structure; the first side wall and the second side wall are arranged oppositely, and the air inlet and the air outlet are in a collinear position.

2. The MEMS thermal conductivity detector structure for GC according to claim 1, wherein, The air inlet is parallel to the surface of the MEMS sensor.

3. The MEMS thermal conductivity detector structure for GC according to claim 2, characterized in that, The air inlet is arranged on the bottom of the detector structure, and the air outlet is arranged on the side wall of the detector structure; the bottom and the side wall are arranged perpendicularly.

4. The MEMS thermal conductivity detector structure for GC according to claim 1, wherein, The air inlet is perpendicular to the surface of the MEMS sensor.

5. The MEMS thermal conductivity detector structure for use in GC according to claim 4, characterized in that, The detection pool is in a trapezoidal cylindrical structure, and the distance between the bottom surface of the detection pool and the surface of the MEMS sensor is 1.8-2 mm.

6. The MEMS thermal conductivity detector structure for GC according to claim 1, wherein, The diameter of the top of the detection pool is 0.15-0.25 mm larger than the diameter of the surface of the MEMS sensor.

7. The MEMS thermal conductivity detector structure for GC of claim 1, wherein, The diameters of the air inlet and the air outlet are 0.6-1.7 mm.

8. The MEMS thermal conductivity detector structure for GC of claim 1, wherein, The air inlet and the air outlet are both provided with a clamping sleeve joint which is used for connecting with an external pipeline.

9. The MEMS thermal conductivity detector structure for GC of claim 1, wherein, ​

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