Spiral one-way or two-way space-time electronic nose based on air-permeable interdigital electrode and application

Abstract

The invention discloses a spiral one-way or two-way space-time electronic nose based on an air-permeable interdigital electrode and application of the spiral one-way or two-way space-time electronic nose. According to the invention, a plurality of breathable rings are designed on the breathable interdigital electrode, and each breathable ring is provided with a plurality of micropores for gas circulation; the whole interdigital electrode is simple in manufacturing process and low in cost; the cavity structure is used for exploring a gas space-time diffusion mechanism. The first cavity is a one-way cavity, a round cavity, a stainless steel cavity with the outer surface connected with a pipeline and a PCB microcavity are adopted, and a plurality of layers of breathable interdigital electrodes are arranged in the one-way cavity. And space-time response fingerprints are constructed through independent resistance signals of each layer of non-breathable sensing area. The second type of bidirectional cavity adopts a circular cavity, a U-shaped stainless steel cavity of which the outer surface is connected with a pipeline, and a PCB microcavity, and carries a plurality of layers of air-permeable interdigital electrodes of which the air enters and exits from the same side. Dynamic identification and classification of volatile organic compounds (VOCs) are finally realized by combining time sequence signals and spatial gradient distribution characteristics of a plurality of layers of sensing units.

Description

Technical Field

[0001] The present invention relates to the technical field of sensing equipment, and in particular to a spiral unidirectional or bidirectional space-time electronic nose based on air-permeable interdigital electrodes and its application. Background Art

[0002] Volatile organic compounds (VOCs) are environmental pollutants, disease markers, and important indicators of food spoilage. Their precise detection is urgently needed in areas such as public safety, medical diagnostics, and smart agriculture. Traditional detection technologies primarily rely on metal oxide semiconductor gas sensors, but these are susceptible to cross-interference in complex multi-component gas environments and struggle to dynamically identify trace VOCs. The recent rise of electronic nose technology, which generates fingerprints through the cross-response of multi-sensor arrays, has significantly improved detection capabilities, but faces core challenges such as bulky systems, complex sensor unit fabrication processes, and high costs. Summary of the Invention

[0003] The present invention aims to address the challenges of existing electronic nose technology, such as large equipment size, complex multi-sensor array fabrication, and significant cross-interference. By providing a spiral, unidirectional, or bidirectional, spatiotemporal electronic nose based on permeable interdigital electrodes and its applications, the invention addresses these issues. By actively regulating the spatiotemporal diffusion path of gases through a spiral cavity structure and combining it with a detachable gradient permeable microporous array, the invention achieves miniaturization while utilizing the multi-channel spatiotemporal response signals of a single gas-sensitive material to dynamically identify complex VOCs. This significantly reduces manufacturing costs and improves detection sensitivity and interference resistance.

[0004] The specific technical solution for achieving the purpose of the present invention is: A spiral unidirectional or bidirectional space-time electronic nose based on breathable interdigital electrodes, characterized by comprising: a unidirectional circuit board or a bidirectional circuit board, a first FPC connector and a second FPC connector connected to the space-time circuit board, a stainless steel unidirectional cavity or a bidirectional cavity composed of an upper stainless steel bidirectional cavity and a lower bidirectional bottom plate, and several layers of breathable interdigital electrode sheets disposed within the unidirectional cavity or bidirectional cavity, wherein the breathable interdigital electrode sheets are provided with electrode positioning holes, a gold electrode, a breathable ring, and an FPC connection end on the front side, and a reinforcement sheet on the back side; positioning holes corresponding to the electrode positioning holes are provided on the unidirectional circuit board or the bidirectional circuit board and the unidirectional cavity or the bidirectional cavity; screws, nuts, sealing rubber rings, and positioning holes are used to securely connect the several layers of interdigital electrode sheets, the unidirectional circuit board or the bidirectional circuit board, and the unidirectional cavity or the bidirectional cavity, and to bring the second connector into contact with the FPC connection end; internal wires within the circuit board electrically connect the first FPC connector and the second FPC connector, wherein the breathable ring contains a plurality of breathable micropores distributed in a circular pattern.

[0005] Furthermore, the unidirectional circuit board is connected to the FPC connection end of the permeable interdigital electrode through a second FPC connector. The stainless steel unidirectional cavity is composed of two cavities with the same structure and an external pipe line connected to the cavity. Several layers of permeable interdigital electrode sheets are arranged in the cavity, fixed in the electrode positioning holes with several screws and nuts, and equipped with sealing rubber rings to ensure air tightness; each layer of the electrode sheets is stacked at 45°, and the permeable area formed by several permeable rings decreases gradually according to the number of layers; after the gas flows in, it is buffered and pre-diffused in the cavity and then enters the spiral stacking area. A diffusion rate gradient is formed by the gradually shrinking permeable area, and a spatiotemporal response fingerprint is constructed by the channel independent resistance signal with the same number of electrode sheets.

[0006] Furthermore, the bidirectional circuit board is connected to the FPC connection end of the breathable interdigitated electrode sheet through a second FPC connector. The bidirectional cavity is a U-shaped structure with air inlet and outlet on the same side formed by the upper layer of the stainless steel bidirectional cavity and the bidirectional lower bottom plate. The upper layer of the stainless steel bidirectional cavity is connected to a double pipeline. Several layers of breathable interdigitated electrode sheets are arranged in the bidirectional cavity, which are fixed in the electrode positioning holes with several screws and nuts, and are equipped with sealing rubber rings to ensure air tightness. Each layer of the electrode sheets is stacked at 45°, and the breathable area formed by several breathable rings decreases gradually according to the number of layers; after the gas flows into the cavity, it is buffered and pre-diffused before entering the spiral stacking area, and a diffusion rate gradient is formed by the gradually shrinking breathable area, and a spatiotemporal response fingerprint is constructed by the channel independent resistance signal with the same number of electrode sheet layers.

[0007] Furthermore, the first FPC connector and the second FPC connector on the unidirectional circuit board or the bidirectional circuit board are arranged on the circuit board according to the corresponding identification, and are connected to the circuit board through a welding process. The internal wires of the circuit board electrically connect the first FPC connector and the second FPC connector to assemble into a unidirectional or bidirectional circuit board.

[0008] Furthermore, the upper layer of the stainless steel bidirectional cavity and the stainless steel unidirectional cavity are prepared by 3D printing using a laser melting (SLM) molding process.

[0009] An application of the above-mentioned spiral unidirectional or bidirectional spatiotemporal electronic nose based on gas permeable interdigital electrodes in volatile gas sensing.

[0010] Furthermore, the preparation of the two-way lower base plate of the organic glass plate includes: A rectangular organic glass plate with a length of 4 to 10 cm, a width of 4 to 10 cm, and a thickness of 1 to 3 mm is selected, and 4 to 10 electrode positioning holes and a shape identical to the upper layer 19 of the stainless steel bidirectional cavity are cut out using a laser.

[0011] Furthermore, the preparation of the sealing rubber ring includes: A silicone pad with a length of 6-20 cm, a width of 6-20 cm, and a thickness of 1 mm was selected. A laser was used to cut out the same shape as the upper layer of the stainless steel bidirectional cavity. Four to ten electrode positioning holes were cut out, and holes of the same size as the PCB microcavity were cut out.

[0012] Advantages of the spiral unidirectional or bidirectional spatiotemporal electronic nose based on air permeable interdigital electrodes of the present invention: 1) The cavity is composed of various parts and can be disassembled and replaced; 2) The design of the breathable interdigitated electrode enables precise control of the diffusion path. The permeable area of the electrode is composed of several breathable rings, each containing multiple micropores, which actively regulate the gas diffusion rate and form a spatiotemporal response gradient. 3) The gas-permeable interdigital electrode array achieves single-material, multi-channel response in its design. Only a single gas-sensitive material is required to be coated on the interdigital electrode area. Combined with a micropore design with different gas permeability areas, it outputs multi-dimensional signals through several layers of independent channels, replacing traditional multi-sensor arrays and significantly reducing costs. 4) A spiral unidirectional spatiotemporal electronic nose achieves gradient diffusion. Several layers of electrodes are stacked at 45°, with the permeability decreasing from large to small. Combined with pre-diffusion in a buffer cavity, this creates a spatiotemporal fingerprint suitable for trace gas identification. 5) A spiral bidirectional space-time electronic nose realizes bidirectional wave path diffusion. It consists of a multi-layer electrode diffusion structure and prolongs the gas contact time through fluid dynamic regulation, thereby enhancing the separation efficiency of mixed VOCs and improving anti-interference performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the explosion of the spiral unidirectional space-time electronic nose of the present invention; Figure 2 Schematic diagram of the spiral unidirectional space-time electronic nose assembly of the present invention; Figure 3 This is a schematic diagram of the explosion of the spiral bidirectional space-time electronic nose of the present invention; Figure 4 Schematic diagram of the spiral bidirectional space-time electronic nose assembly of the present invention; Figure 5 This is a front view schematic diagram of the breathable interdigital electrode of the present invention; Figure 6 Schematic diagram of the back side of the breathable interdigitated electrode of the present invention; Figure 7 This is a front view of a one-way circuit board according to the present invention; Figure 8 This is a schematic diagram of the back side of the one-way circuit board of the present invention; Figure 9 This is a schematic diagram of the stainless steel one-way cavity of the present invention; Figure 10 This is a front view of the bidirectional circuit board of the present invention; Figure 11 This is a schematic diagram of the stainless steel bidirectional cavity of the present invention; Figure 12 This is a schematic diagram of the bidirectional lower floor of the present invention; Figure 13 Schematic diagram of the sealing rubber ring of the present invention; Figure 14 This is a data graph of the spiral unidirectional space-time electronic nose of the present invention testing 10ppm n-hexanol; Figure 15 This is a data graph showing the test of 10 ppm n-hexanol by the spiral bidirectional space-time electronic nose of the present invention. DETAILED DESCRIPTION

[0014] The following is a complete, clear, and detailed description of the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings and specific implementation methods. The described embodiments are partial embodiments of the present invention, not all embodiments. Based on the described 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.

[0015] See Figure 1-13 The present invention provides a spiral unidirectional or bidirectional space-time electronic nose based on breathable interdigital electrodes. The electronic nose includes a unidirectional circuit board 1, a first FPC connector 2, a second FPC connector 3, an electrode positioning hole 4, an azimuth positioning hole 5, a PCB microcavity 6, an M1.6 nut 7, a stainless steel unidirectional cavity 8, a sealing rubber ring 9, a breathable interdigital electrode sheet 10, an M1.6 screw 11, a breathable ring 12, breathable micropores 13, a PI reinforcement sheet 14, a unidirectional cavity air pipe connection 15, a unidirectional cavity buffer cavity 16, a gold electrode 17, a bidirectional circuit board 18, a stainless steel bidirectional cavity upper layer 19, a plexiglass bidirectional lower bottom plate 20, and an FPC connection end 21.

[0016] The breathable interdigitated electrode sheet 10 is designed with several breathable rings 12 and gold electrodes 17 on a flexible polyimide (PI) film substrate. Each breathable ring has a central micropore distributed in a circular pattern. Each breathable ring has multiple breathable micropores 13 and a PI reinforcement sheet 14 on the back.

[0017] The stainless steel bidirectional cavity upper layer 19 and the stainless steel unidirectional cavity 8 are both manufactured by 3D printing using a laser melting (SLM) molding process.

[0018] The bidirectional lower bottom plate 20 is a circular organic glass thin plate, and 4 to 10 electrode positioning holes are symmetrically cut on its surface to form the same shape as the stainless steel bidirectional cavity upper layer 19.

[0019] The sealing rubber ring 9 is cut into the same shape as the upper layer 19 of the stainless steel bidirectional cavity using a laser, and is cut into holes of the same size as 4 to 10 electrode positioning holes and the same size as the PCB microcavity 6.

[0020] A spiral unidirectional space-time electronic nose is composed of a stainless steel unidirectional cavity 8, a sealing rubber ring 9, a unidirectional circuit board 1, several breathable interdigital electrode sheets 10, a sealing rubber ring 9, and a stainless steel unidirectional cavity 8 stacked in sequence from top to bottom, with the electrode positioning holes 4 aligned one by one. Screws 11 are inserted from 4 to 10 electrode positioning holes of the stainless steel unidirectional cavity 8 and then tightened with nuts 7.

[0021] A spiral bidirectional space-time electronic nose is composed of a stainless steel bidirectional cavity upper layer 19, a sealing rubber ring 9, a bidirectional circuit board 18, several breathable interdigital electrode sheets 10, a sealing rubber ring 9, and a plexiglass bidirectional lower bottom plate 20 stacked in sequence from top to bottom. The electrode positioning holes 4 are aligned one by one, and screws 11 are inserted through 4 to 10 electrode positioning holes of the stainless steel bidirectional cavity upper layer 19 and then tightened with nuts 7. Example

[0022] Assembly of a spiral unidirectional spatiotemporal electronic nose based on gas permeable interdigital electrodes, see Figure 1 、 Figure 2 ; Stack the stainless steel unidirectional cavity 8, sealing rubber ring 9, unidirectional circuit board 1, 7 breathable interdigital electrode sheets 10, sealing rubber ring 9, and stainless steel unidirectional cavity 8 from top to bottom, and align their electrode positioning holes 4 one by one. Connect the second FPC connector 3 on the unidirectional circuit board 1 to the FPC connection end 21 of the breathable interdigital electrode sheet 10, insert the screws 11 into the 4th to 10th electrode positioning holes of the stainless steel unidirectional cavity 8, and then tighten and fix them with nuts 7. Example

[0023] Assembly of a spiral bidirectional spatiotemporal electronic nose based on gas permeable interdigital electrodes, see Figure 3 、 Figure 4 ; The stainless steel bidirectional cavity upper layer 19, the sealing rubber ring 9, the bidirectional circuit board 18, the 8 breathable interdigital electrode sheets 10, the sealing rubber ring 9, and the organic glass plate bidirectional lower bottom plate 20 are stacked from top to bottom, and their electrode positioning holes 4 are aligned one by one. The second FPC connector 3 on the bidirectional circuit board 18 is connected to the FPC connection end 21 of the breathable interdigital electrode sheet 10, and the screws 4 are inserted into the 4 to 10 electrode positioning holes of the stainless steel bidirectional cavity upper layer 19, and then tightened with nuts 7. Example

[0024] Preparation of the gas permeable interdigitated electrode sheet 10, see Figure 5 、 Figure 6 ; First, we designed the design for the breathable interdigital electrodes. Based on the design requirements, we selected a polyimide (PI) substrate for processing. We attached a PI reinforcement sheet to the back of the FPC connector area, using 3M adhesive to ensure mechanical strength. Wires were designed into the electrodes, and the exposed gold electrodes 17 were gold-plated to enhance their oxidation resistance. The outer contours were then laser cut according to the design documentation. Example

[0025] Preparation of unidirectional circuit board 1 and bidirectional circuit board 18, see Figure 7 、 Figure 8 、 Figure 10 First, design drawings for a unidirectional circuit board and a bidirectional circuit board, and then produce the circuit boards according to the design drawings. Apply medium-temperature solder paste to the exposed pads, and place the first FPC connector 2 and the second FPC connector 3 on the two circuit boards according to the corresponding markings. Next, heat the circuit boards on a 200° constant-temperature heating table. After the solder paste melts, remove the circuit boards and cool them to room temperature. The internal wires of the circuit boards electrically connect the first FPC connector 2 and the second FPC connector 3, and use a multimeter to check for solder leaks. Thus, the unidirectional circuit board 1 and the bidirectional circuit board 18 are produced. Example

[0026] The preparation of the stainless steel one-way cavity 8 and the stainless steel two-way cavity upper layer 19 is as follows: Figure 9 、 Figure 11 ; First, the design drawings of the stainless steel bidirectional cavity upper layer 19 and the stainless steel unidirectional cavity 8 were designed, and the stainless steel cavity was prepared by 3D printing using the laser melting (SLM) molding process. Example

[0027] Preparation of organic glass plate two-way lower bottom plate 20 and sealing rubber ring 9, see Figure 12 and Figure 13 ; 6.1: Take a 20cm x 20cm, 2mm thick plexiglass plate and use a CO2 laser at 70% power and a cutting speed of 50mm / s to cut 4 to 10 through-holes with a diameter of 1.6mm into the plate as electrode positioning holes 4. Finally, use the same power and cutting speed to cut out the circular shape. The plexiglass plate has a two-way bottom plate 20.

[0028] 6.2: Take a piece of silicone film with a thickness of 0.2mm and a size of 10cm*10cm. Use a CO2 laser at 30% power and a cutting speed of 200mm / s to cut a circular outline, 4 to 10 through-holes with a diameter of 1.6mm as electrode positioning holes, and a circular through-hole with a diameter of 18mm corresponding to the PCB microcavity on the silicone film to make a sealing rubber ring 9. Example

[0029] An application of a spiral unidirectional spatiotemporal electronic nose based on permeable interdigital electrodes involves connecting a stainless steel unidirectional chamber 8 to a polytetrafluoroethylene tube and N2 flow. The interdigital electrode sensor array in the chamber is flushed with a flow rate of 1000 seem to stabilize the baseline of the interdigital electrode sensor array. The sensor array, coated with a gas-sensitive material, is then exposed to 10 ppm of n-hexanol VOCs for 3 minutes. The resistance change of the permeable interdigital electrode sheets (7 in total) is measured using a multi-channel benchtop multimeter. Finally, N2 is passed through the interdigital electrode sensor array to flush out the previously introduced VOCs. Figure 14 As can be seen from the figure: the electronic nose can realize the gradient differentiation of n-hexanol VOCs and has high-performance volatile gas sensing capabilities. Example

[0030] An application of a spiral dual-time space electronic nose involves connecting one end of the upper layer 19 of a stainless steel bidirectional cavity to a polytetrafluoroethylene tube and N2 flow. The interdigital electrode sensor array in the chamber is flushed with a flow rate of 1000 seem to stabilize the baseline of the interdigital electrode sensor array. The sensor array, coated with gas-sensitive material, is then exposed to a 10 ppm concentration of n-hexanol VOCs for 3 minutes. The resistance change of the gas permeability interdigital electrodes (a total of 8) is measured using a multi-channel benchtop multimeter. Finally, N2 is passed through the sensor array to flush out the previously introduced VOCs. Figure 15 ; It can be seen from the figure that the electronic nose realizes the gradient differentiation of n-hexanol VOCs and has high-performance volatile gas sensing capabilities.

Claims

1. A spiral unidirectional or bidirectional spatiotemporal electronic nose based on gas permeable interdigital electrodes, characterized in that: include: A unidirectional circuit board (1) or a bidirectional circuit board (18), a first FPC connector (2) and a second FPC connector (3) connected to the circuit board, a stainless steel unidirectional cavity (8) or a bidirectional cavity composed of an upper stainless steel bidirectional cavity (19) and a bidirectional lower bottom plate (20), and several layers of breathable interdigitated electrode sheets (10) arranged in the unidirectional cavity or the bidirectional cavity, wherein the breathable interdigitated electrode sheets (10) are provided with electrode positioning holes (4), gold electrodes (17), breathable rings (12) and FPC connection terminals (21) on the front side, and reinforcing sheets (14) on the back side; the unidirectional Positioning holes corresponding to the electrode positioning holes (4) are provided on the circuit board (1) or the bidirectional circuit board (18) and the one-way cavity (8) or the bidirectional cavity; the several layers of interdigitated electrode sheets (10), the one-way circuit board (1) or the bidirectional circuit board (18) and the one-way cavity (8) or the bidirectional cavity are fixedly connected by screws (11), nuts (7), sealing rubber rings (9) and the positioning holes, and the second FPC connector (3) is connected to the FPC connection end (21); wherein the air ring (12) contains a plurality of air permeable micropores (13) distributed in a circular equidistant manner.

2. The spiral unidirectional or bidirectional space-time electronic nose according to claim 1, characterized in that: The unidirectional circuit board (1) is connected to the FPC connection end (21) of the permeable interdigital electrode (10) through a second FPC connector (3); the stainless steel unidirectional cavity (8) is composed of two cavities with the same structure and an external pipe line connected to the cavity; several layers of permeable interdigital electrode sheets (10) are arranged in the cavity, fixed in the electrode positioning holes (4) with several screws (11) and nuts (7), and equipped with a sealing rubber ring (9) to ensure air tightness; each layer of the electrode sheet (10) is stacked at 45 degrees, and the permeable area formed by several permeable rings (12) decreases gradually according to the number of layers; after the gas flows in, it is buffered and pre-diffused in the cavity and then enters the spiral stacking area, forming a diffusion rate gradient through the layer-by-layer shrinking permeable area, and constructing a spatiotemporal response fingerprint by the channel independent resistance signal with the same number of electrode sheet layers.

3. The spiral unidirectional or bidirectional space-time electronic nose according to claim 1, characterized in that: The bidirectional circuit board (18) is connected to the FPC connection end (21) of the breathable interdigital electrode sheet (10) through a second FPC connector (3). The bidirectional cavity is a U-shaped structure with air inlet and outlet on the same side formed by the upper layer (19) of the stainless steel bidirectional cavity and the bidirectional lower bottom plate (20). The upper layer (19) of the stainless steel bidirectional cavity is connected to a double pipeline outside the cavity. Several layers of breathable interdigital electrode sheets (10) are arranged in the bidirectional cavity and fixed in the electrode positioning holes (4) with several screws (11) and nuts (7). A sealing rubber ring (9) is provided to ensure air tightness. Each layer of the electrode sheets is stacked at 45 degrees, and the breathable area formed by several breathable rings (12) decreases gradually according to the number of layers. After the gas flows into the cavity, it is buffered and pre-diffused and then enters the spiral stacking area. A diffusion rate gradient is formed by the gradually shrinking breathable area, and a spatiotemporal response fingerprint is constructed by the channel independent resistance signal with the same number of electrode sheet layers.

4. The spiral unidirectional or bidirectional space-time electronic nose according to claim 1, characterized in that: The one-way circuit board (1) or the two-way circuit board (18) has a first FPC connector (2) and a second FPC connector (3) arranged on the circuit board according to corresponding markings, connected to the circuit board through a welding process, and the internal wires of the circuit board electrically connect the first FPC connector (2) and the second FPC connector (3).

5. The spiral single or bidirectional space-time electronic nose according to claim 1, characterized in that: The stainless steel bidirectional cavity upper layer (19) and the stainless steel unidirectional cavity (8) are prepared by 3D printing using a laser melting process.

6. Use of the spiral unidirectional or bidirectional spatiotemporal electronic nose based on gas permeable interdigital electrodes according to claim 1 in volatile gas sensing.

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