High-sensitivity flexible porous sensor and 3D printing preparation method thereof

Abstract

The invention relates to a high-sensitivity flexible porous sensor and a 3D printing preparation method thereof.The product comprises a sensor body, the two ends of the sensor body are connected with wires, and the sensor body is a multi-layer composite material formed by stacking and arranging a plurality of fuses up and down; the fuses in any layer of the sensor main body are arranged in parallel; an interlayer hole is formed between any two adjacent layers of fuses of the sensor main body; micropores are formed inside and on the surface of the fuse wire; the fuse wire comprises a polymer matrix and a conductive filler uniformly distributed in the polymer matrix; the polymer matrix is a polymer which can generate volume change when external conditions change; during preparation, a fusion 3D printing technology is adopted, a composite material system is fused and then extruded from a spinning nozzle to form fuses, the fuses are stacked up and down to obtain a sensor main body, and the two ends of the sensor main body are connected with wires to form the high-sensitivity flexible porous sensor. The product disclosed by the invention has the characteristics of high sensitivity and flexibility, and has various stimulation responses; the preparation method is simple.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors and relates to a highly sensitive flexible porous sensor and a preparation method thereof. Background Art

[0002] As a current research hotspot, the use of melt 3D printing technology to prepare sensors has the advantages of rapid prototyping, simple operation, and flexible device structure design, and is gradually showing its unique advantages and potential. This technology not only combines the convenience and efficiency of 3D printing, but also integrates the precision and functionality of sensor technology, bringing revolutionary changes to the field of sensor manufacturing.

[0003] Patent ZL202210689541.4 discloses a piezoelectric sensor and a method for preparing it. This patent uses 3D printing to simultaneously extrude and mold conductive materials and piezoelectric materials to prepare a piezoelectric sensor with a parallel structure. It innovates the traditional printing method, enriches the shape and structure of the piezoelectric sensor, and improves the performance of the sensor. However, the deformation generated inside the sensor is small and the sensitivity is still not high.

[0004] The literature (ACS Appl. Nano Mater. 2023, 6, 4522-4531) uses 3D printing technology to prepare a flexible stretchable TPU-based sensor, which can respond to and detect human joint movements. However, the sensitivity of the sensor is limited (GF=1.85) and can only respond to a single stretch.

[0005] Therefore, it is of great significance to study a highly sensitive flexible porous sensor and a preparation method thereof to solve the problems existing in the prior art. Summary of the invention

[0006] The purpose of the present invention is to solve the problems existing in the prior art and to provide a highly sensitive flexible porous sensor and a 3D printing preparation method thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A highly sensitive flexible porous sensor comprises a sensor body, both ends of which are connected with wires (outputting electrical signals), and the sensor body is a multilayer composite material formed by stacking a plurality of fuses in an up-and-down manner;

[0009] The fuses are arranged in parallel in any layer of the sensor body;

[0010] An interlayer hole is formed between any two adjacent layers of fuses of the sensor body;

[0011] The fuse has micropores inside and on the surface;

[0012] The fuse comprises a polymer matrix and a conductive filler, wherein the conductive filler is evenly distributed in the polymer matrix and forms a conductive network;

[0013] The polymer matrix refers to the polymer that can undergo volume changes when external conditions change;

[0014] When external conditions change, the volume of the polymer changes, which causes the spacing between the conductive fillers in the polymer and the contact points between the conductive fillers to change, thereby changing the conductive network and causing a change in resistance; the contact point is the part where the conductive filler contacts.

[0015] Micropores and interlayer pores cooperate with each other to form a porous structure. Under small external stimuli, when the volume of the polymer matrix changes, the micropores are more likely to deform, and the deformation is obvious, so that the spacing between the conductive fillers in the polymer and the contact points between the conductive fillers change significantly, thereby responding to small external stimuli in a timely manner; and under external stimuli, the changes in interlayer pores will also squeeze the micropores in the fuse to form new stimulus transmission, thereby amplifying the electrical signal. Therefore, the micropores and interlayer pores work together to make the highly sensitive flexible porous sensor more sensitive to changes in small deformation quantities.

[0016] Porous sensors are also disclosed in the prior art, such as the piezoelectric sensor in Patent ZL202210689541.4, but its mechanism is completely different from that of the present invention. The mechanism of Patent ZL202210689541.4 is that under the action of pressure, the arrangement of dipoles changes, resulting in charge accumulation and output of electrical signals. The change in deformation will affect the arrangement of dipoles, and the relationship is positively correlated.

[0017] As the preferred technical solution:

[0018] As described above, the highly sensitive flexible porous sensor has an equivalent circular diameter of 0.05-0.15 mm between interlayer pores, a spindle-shaped micropore, and an equivalent circular diameter of 10-150 μm (referring to the longest distance between any two points of the irregular pore).

[0019] In a highly sensitive flexible porous sensor as described above, the arrangement directions of the fuses in adjacent layers are perpendicular to each other, and the interlayer holes are triangular-shaped holes surrounded by two adjacent fuses in any layer and the upper surface or lower surface of the adjacent layer (the triangular-shaped hole is basically the same as the triangle, except that two sides are curved and one side is straight).

[0020] In a highly sensitive flexible porous sensor as described above, the arrangement directions of all layers of fuses are parallel to each other, and the arrangement positions of all layers of fuses in the vertical direction are the same, and the interlayer holes are rhombus-shaped holes surrounded by the upper surfaces or lower surfaces of two adjacent fuses in any layer and the corresponding two adjacent fuses in the adjacent layer (the rhombus-shaped shape is basically the same as the rhombus, the difference being that each side is curved).

[0021] As described above, a highly sensitive flexible porous sensor, the polymer matrix is ​​thermoplastic polyurethane (TPU), thermoplastic polyester elastomer (TPEE), polyolefin thermoplastic elastomer (POE), polystyrene elastomer (TPES), polyether ester elastomer (EE), polyamide elastomer (TPAE), polyvinylidene fluoride (PVDF), polylactic acid (PLA), polymethyl methacrylate (PMMA) or polyvinyl alcohol (PVA); the conductive filler is carbon black (CB), multi-walled carbon nanotubes (MWCNTs), graphene (Graphene), expanded graphite (EG), graphene oxide (rGO), carbon fiber (sCF), silver nanowires (AgNWs) or gold nanowires (AuNWs); the polymer matrix selected by the present invention can simultaneously respond to stress, temperature, humidity and VOC, while the prior art, such as patent ZL202210689541.4, can only respond to a single stimulus of pressure.

[0022] In the highly sensitive flexible porous sensor as described above, the mass ratio of the polymer matrix to the conductive filler is 9:1 to 7:3; the volume of the micropores accounts for 10 to 60% of the volume of the fuse.

[0023] As described above, a highly sensitive flexible porous sensor, the fuse is a parallel composite fuse; the fuse also contains other fillers, the other fillers are polyacrylonitrile fibers, the polyacrylonitrile fibers are temperature-sensitive and can improve the sensitivity of temperature-sensitive response, and the polyacrylonitrile fibers are uniformly distributed in the polymer matrix; the addition amount of the polyacrylonitrile fibers is 0.5 to 3 wt% of the fuse.

[0024] As described above, the high-sensitivity flexible porous sensor has a strain response sensitivity of 4 to 500, a temperature response sensitivity of 0.3 to 1% / °C, a humidity response sensitivity of 1 to 3, a response sensitivity of chloroform of 0.1 to 5 (5 to 1000 ppm), a response sensitivity of methanol of 0.1 to 4 (5 to 1000 ppm), a response sensitivity of acetone of 0.1 to 2 (5 to 1000 ppm), a response sensitivity of ether of 0.1 to 3 (5 to 1000 ppm), and a response sensitivity of hexane of 0.1 to 4 (5 to 1000 ppm). Chloroform, methanol, acetone and ether are all VOCs, and different VOCs have different response sensitivities.

[0025] The present invention also provides a method for preparing a highly sensitive flexible porous sensor as described above, wherein the composite material system is melted by using a melt 3D printing technique, and then extruded from a spinneret to form a fuse, and the fuse is stacked and arranged up and down (i.e., 3D printing) to obtain a multilayer composite material, i.e., a sensor body, and wires are connected at both ends of the sensor body to form a highly sensitive flexible porous sensor;

[0026] The composite material system includes a polymer matrix, a conductive filler and a foaming agent. The foaming agent and the polymer matrix generate micropores during the melting process. The principle is that during the 3D melt extrusion molding process of the composite wire of the polymer matrix and the foaming agent, since the nozzle temperature is higher than the decomposition temperature of the foaming agent, the extruded composite wire realizes in-situ foaming during the deposition process, thereby forming a fusible wire with internal micropores.

[0027] As the preferred technical solution:

[0028] A method for preparing a highly sensitive flexible porous sensor as described above, wherein the spinneret is a two-component spinneret; two composite material systems are melt-extruded from two spinneret holes of the two-component spinneret to form parallel composite fuses; the structural design of the two-component spinneret refers to CN202210689541.4;

[0029] The polymer matrix in the two composite systems can be the same or different, the conductive filler can be the same or different, and the blowing agent can be the same or different;

[0030] Compared with single-component fuses, the parallel composite fuses have more diverse multi-level regulation of microporous structures and are flexible and controllable. Due to the different selections of polymer matrices and foaming agents, at least two different micropores are formed inside the parallel composite fuses (including micropores inside two polymer matrices and pores at the interface of two polymer matrices); when the polymer matrix and the foaming agent are the same, the sizes of the micropores can also be different by different contents of the foaming agent;

[0031] The foaming agent is AC foaming agent or thermal expansion microspheres.

[0032] In the method for preparing a highly sensitive flexible porous sensor as described above, the amount of foaming agent added is 0.5-20wt% of the composite material system. The more foaming agent is added, the more the number / size of micropores in the fuse will increase; for different polymers, the pores formed by the foaming agent will also be different.

[0033] The method for preparing a highly sensitive flexible porous sensor as described above, the process parameters include: nozzle diameter of 0.4-0.8 mm; nozzle temperature of 180-270° C.; printing speed of 10-40 mm / s; bottom plate temperature of 60-150° C.; layer thickness of 0.2-0.4 mm; filling path of linear filling or concentric circle filling; filling angle of 0°-90°;

[0034] These process parameters affect the number, size, shape, and distribution of micropores and interlayer pores as follows:

[0035] (1) Number of micropores and interlayer pores:

[0036] Nozzle diameter: The larger the diameter, the thicker the extruded filament, the more interlayer pores there are, and the more micropores there are in the filament at the same polymer / filler / foaming agent ratio;

[0037] Nozzle temperature: When the nozzle temperature is high, the foaming agent foams more fully, and the number of micropores in the fuse increases; the fuse melts fully, the fuses are well bonded, and the number of interlayer pores decreases;

[0038] Printing speed: Fast speed will shorten the melting time of the fuse, resulting in insufficient foaming, which will reduce the number of micropores in the fuse; insufficient bonding between fuses will increase the number of interlayer pores;

[0039] Bottom plate temperature: mainly affects the micropores in the first layer of fuse. If the bottom plate temperature is high, the first layer of fuse deposited on the bottom plate may continue to foam, increasing the number of micropores inside the fuse (the bottom plate temperature only affects the bottom layer. When actually testing the sensitivity, the bottom layer can be manually removed to avoid the impact);

[0040] The parameters of layer thickness, filling path and filling angle mainly affect the number of interlayer holes; specifically:

[0041] Layer thickness: affects the number of interlayer holes; the smaller the layer thickness, the more fuses are extruded, the tighter the bond between fuses, and the fewer interlayer holes;

[0042] Filling path: affects the number of interlayer holes; the straight-line filling fuses are tightly bonded and have fewer interlayer holes;

[0043] Filling angle: affects the number of interlayer holes; when a single filling angle is used (0°~90°), the larger the filling angle, the more interlayer holes there are; when filling at multiple angles (0° / 90°, ±45°), 0° / 90° filling results in tight adhesion between fuses and a small number of interlayer holes;

[0044] (2) shape;

[0045] Printing speed affects the shape of micropores; the stretching effect during extrusion causes spindle-shaped pores to form. The faster the printing speed, the more standard the spindle shape.

[0046] (3) The size of micropores and interlayer pores;

[0047] The nozzle diameter and nozzle temperature affect the size of micropores. When the nozzle diameter is large, the extrusion of the melt leads to small micropores. When the nozzle temperature is high, the foaming is more complete, forming larger micropores.

[0048] The base plate temperature is high, which causes the fuse to foam twice / continuously. The micropores of the first layer of fuse will be larger than those of other layers.

[0049] When the layer thickness is small, melt extrusion will reduce the micropore size;

[0050] The filling rate is large and the interlayer pores are small; Figure 6 As shown, it is a schematic diagram of fuse distribution with different filling rates, which shows that the greater the filling rate, the more interlayer holes there are;

[0051] like Figure 4 The figure shows the schematic diagram of the linear filling and concentric circle filling paths; in the concentric circle filling path, the interlayer pores are smaller;

[0052] The filling angle also affects the shape of the interlayer pores. When the filling angle is single (0° to 90°), the interlayer pores are rhombus-like. When the filling angle is multi-angle (0° / 90°, ±45°), the interlayer pores are triangular-like or rhombus-like.

[0053] (4) interlayer pore distribution;

[0054] The filling angle affects the distribution of interlayer pores; e.g. Figure 5 The figure shows the schematic diagram of fuse distribution at different filling angles. When the filling angle is single (0°~90°), the distribution of interlayer holes (in the same layer) is consistent with the filling angle, and the holes between the upper and lower adjacent layers are arranged in parallel. When the filling angle is multi-angle (0° / 90°, ±45°), the upper and lower interlayer holes are in a vertical relationship, the distribution of the upper and lower interlayer holes is consistent with the filling angle, and the adjacent holes in the same layer are arranged in parallel.

[0055] The effects of micropore size, micropore number, interlayer pore size, interlayer pore number and interlayer pore distribution on the response are as follows:

[0056] The smaller the micropore size, the higher the sensitivity, because the micropore can change (squeeze and stretch) more sensitively under the same external stimulus;

[0057] The more micropores there are, the higher the sensitivity is, because the more micropores there are inside the fuse, the more sensitive it is to external stimuli;

[0058] The more interlayer pores there are, the higher the sensitivity is, because the more there are, the more micropores there are inside the interlayers, and they are more sensitive to external stimuli;

[0059] The larger the interlayer pore size, the higher the sensitivity, because the interlayer pores can change more sensitively (squeeze and stretch) under the same external stimulus;

[0060] The distribution of interlayer pores will only affect the stress-stretching response. This is because during stress stretching, the volume of the polymer matrix changes unevenly and deforms along the direction of stress stretching. For other external stimuli that cause the polymer volume to expand uniformly, the distribution of interlayer pores will not affect its sensitivity.

[0061] Beneficial effects:

[0062] (1) In the highly sensitive flexible porous sensor of the present invention, micropores and interlayer pores cooperate with each other to form a porous structure, so that the highly sensitive flexible porous sensor is more sensitive to changes in small deformation amounts and can achieve multiple stimulus responses (temperature, humidity, VOCs, etc.);

[0063] (2) A 3D printing preparation method of a high-sensitivity flexible porous sensor of the present invention utilizes melt 3D printing technology and in-situ foaming to prepare a high-sensitivity flexible porous sensor. The porous structure of the high-sensitivity flexible porous sensor has the characteristics of multi-level and adjustable, which gives the sensor high sensitivity and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 Schematic diagram of a highly sensitive flexible porous sensor;

[0065] Figure 2 It is a cross-sectional schematic diagram of the distribution of holes between fuse layers at a filling angle of 0 / 90° and a filling rate of 100% in Example 5;

[0066] Figure 3 Schematic cross-sectional view of the distribution of holes between fuse layers at a filling angle of 0° and a filling rate of 100% in Example 1;

[0067] Figure 4 The top view of the hole size between fuses controlled by different filling paths, where the left image is a linear filling and the right image is a concentric circle filling;

[0068] Figure 5 It is a top view schematic diagram of the internal fuse distribution at different filling angles;

[0069] Figure 6 It is a top view schematic diagram of internal fuse distribution with different filling rates;

[0070] Figure 7 Schematic diagram of the cross section before (two composite material systems) and after (parallel composite fuses) 3D printing melt extrusion;

[0071] Figure 8Schematic diagram of a highly sensitive flexible porous sensor with a filling angle of 0° / 90° (a) and a stereogram of its upper surface (b);

[0072] Fig. 9 This is a schematic diagram of the changes in the interlayer pores and micropores in the fuse before and after stretching when the extruded fuse is filled at 0° / 90°;

[0073] Fig.10 Schematic diagram of the change of the internal conductive path of the fuse under tensile strain and release (resistance change);

[0074] Fig.11 This is a schematic diagram of the change of the conductive path inside the fuse before and after VOCs gas adsorption (resistance change);

[0075] Among them, 1-sensor body, 2-conducting wire, 3-conductive tape, 4-fuse, 5-interlayer hole, 6-polymer matrix A, 7-polymer matrix B, 8-foaming agent, 9-micropores, 10-conductive filler, 11-conductive path. DETAILED DESCRIPTION

[0076] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0077] The test methods involved in the performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0078] (1) Strain response sensitivity: Use an electronic universal testing machine and a digital multimeter to test and calculate the strain response sensitivity during stretching; use the tensile strain range to represent flexibility, and the strain range is 0.5-500%; fix the sensor sample on the universal testing machine and connect it to the digital multimeter, and set the stretching rate of the testing machine to 10 mm / min; measure each strain 3 times during the sensitivity test; the strain response sensitivity calculation formula is as follows:

[0079] GF=(ΔR / R 0 ) / ε;

[0080] Where ΔR is the resistance change rate, R 0 is the initial resistance, ε is the strain (%), and GF (Gauge Factor) is the sensitivity factor;

[0081] (2) Temperature response sensitivity: The sample was placed in a glass container filled with silicone oil (manufacturer: Shanghai Yuanye Biotechnology Co., Ltd., CAS: 63148-62-9) and heated on a heating table (using a thermocouple to measure the silicone oil temperature in real time). The sample was connected to a digital multimeter to test the change in electrical signals; the silicone oil temperature T was 25°C, 50°C, 75°C, 100°C, 125°C, and 150°C; during the sensitivity test, each temperature was measured 3 times; the temperature response sensitivity calculation formula is as follows:

[0082] S=(ΔR / R 0 ) / T;

[0083] (3) Humidity response sensitivity: The samples were placed in glass containers containing saturated salt solution of calcium chloride, saturated salt solution of magnesium chloride, saturated salt solution of potassium carbonate, saturated salt solution of sodium chloride and saturated salt solution of potassium nitrate, respectively, and the relative humidity (RH) was controlled at 16%, 35%, 45%, 75% and 95%, respectively. The change of electrical signal was tested with a digital multimeter. During the sensitivity test, each humidity was measured 3 times. The humidity response sensitivity calculation formula is as follows:

[0084] S = resistance change rate (ΔR / R 0 ) / humidity change (RH / %);

[0085] (4) VOCs gas responsiveness: Gas responsiveness can reflect the speed of the sensor's response in different gas atmospheres, that is, the resistance change rate (ΔR / R) under a certain gas concentration. 0 ) changes with time, the gas concentration is 5 to 1000ppm; the specific test process is: the two ends of the sample are connected to a digital multimeter and fixed in a glass chamber, and the glass chamber maintains a continuous airflow of 200ml / s; the gas response performance test is carried out at room temperature (25°C) and a relative humidity of 15%. Before the gas responsiveness test, dry air is used as a purge gas to purge the entire chamber for 30s, and then the test gas VOCs is injected. During the gas responsiveness test, VOCs (15s) and dry air (100s) are alternately flowed to measure each concentration 3 times.

[0086] Example 1

[0087] A 3D printing preparation method for a highly sensitive flexible porous sensor, the specific steps are as follows:

[0088] (1) Preparation of raw materials:

[0089] The composite material system A includes a polymer matrix A, a conductive filler A and 0.5 wt% of a foaming agent A; wherein the mass ratio of the polymer matrix A to the conductive filler A is 9:1;

[0090] The composite material system B includes a polymer matrix B, a conductive filler B and 0.5 wt% of a foaming agent B; wherein the mass ratio of the polymer matrix B to the conductive filler B is 7:3;

[0091] Polymer matrix A: thermoplastic polyurethane, manufacturer: BASF, Germany, item number: 1185A;

[0092] Polymer matrix B: thermoplastic polyurethane, manufacturer: BASF, Germany, item number: 1185A;

[0093] Conductive filler A: carbon black, manufacturer: Adamas, product number: 01018339;

[0094] Conductive filler B: carbon fiber, manufacturer: Zhongfu Shenying Carbon Fiber Co., Ltd., item number: 1K;

[0095] Foaming agent A: AC foaming agent, manufacturer: Shanghai McLean Biochemical Technology Co., Ltd., CAS: 123-77-3;

[0096] Foaming agent B: AC foaming agent, manufacturer: Shanghai McLean Biochemical Technology Co., Ltd., CAS: 123-77-3;

[0097] (2) Using melt 3D printing technology, two composite materials are melt-extruded from two spinnerets of a two-component spinneret to form parallel composite fuses, which are stacked up and down to obtain a sensor body. Wires are connected at both ends of the sensor body to form a highly sensitive flexible porous sensor.

[0098] The process parameters include: nozzle diameter is 0.4mm; nozzle temperature is 220℃; printing speed is 10mm / s; base plate temperature is 90℃; layer thickness is 0.2mm; filling path is linear filling; filling angle is 0°, and filling rate is 100%;

[0099] like Figure 3As shown, the sensor body in the finally obtained high-sensitivity flexible porous sensor is a 4-layer composite material formed by stacking multiple fuses 4 up and down; the fuses in any layer of the sensor body are arranged in parallel; interlayer pores are formed between any two adjacent layers of fuses in the sensor body, and the equivalent circular diameter of the interlayer pores is 0.05mm; there are micropores inside and on the surface of the fuse, the micropores are spindle-shaped, and the volume of the micropores accounts for 10% of the volume of the fuse; the equivalent circular diameter of the micropores in the fuse formed by the composite material system A is 10-20μm, and the equivalent circular diameter of the micropores in the fuse formed by the composite material system B is 10-20μm. The diameter is 15 to 25 μm; the fuse comprises a polymer matrix and a conductive filler, and the conductive filler is uniformly distributed in the polymer matrix to form a conductive network; the strain response sensitivity of the high-sensitivity flexible porous sensor is 4, the temperature response sensitivity is 0.3% / °C, the humidity response sensitivity is 1, the response sensitivity of chloroform is 0.1 (5 ppm), the response sensitivity of methanol is 0.1 (5 ppm), the response sensitivity of acetone is 0.1 (5 ppm), the response sensitivity of ether is 0.1 (5 ppm), and the response sensitivity of hexane is 0.1 (5 ppm).

[0100] Example 2

[0101] A 3D printing preparation method for a highly sensitive flexible porous sensor, the specific steps are as follows:

[0102] (1) Preparation of raw materials:

[0103] The composite material system A includes a polymer matrix A, a conductive filler A and 1 wt% of a foaming agent A; wherein the mass ratio of the polymer matrix A to the conductive filler A is 8:2;

[0104] The composite material system B includes a polymer matrix B, a conductive filler B and 15 wt % of a foaming agent B; wherein the mass ratio of the polymer matrix B to the conductive filler B is 8:2;

[0105] Polymer matrix A: thermoplastic polyester elastomer, manufacturer: SK Company of South Korea, item number: S2008;

[0106] Polymer matrix B: polyamide elastomer, manufacturer: DuPont, USA, product number: 7246WT408;

[0107] Conductive filler A: multi-walled carbon nanotubes, manufacturer: Sane Chemical Technology (Shanghai) Co., Ltd., product number: 308068-56-6;

[0108] Conductive filler B: nano silver wire, manufacturer: Xianfeng Nano, product number: 102071;

[0109] Foaming agent A: thermal expansion microspheres, manufacturer: American Boliken, product number: 220DU30;

[0110] Foaming agent B: thermal expansion microspheres, manufacturer: American Boliken, product number: 220DU30;

[0111] (2) Using melt 3D printing technology, two composite materials are melt-extruded from two spinnerets of a two-component spinneret to form parallel composite fuses, which are stacked up and down to obtain a sensor body. Wires are connected at both ends of the sensor body to form a highly sensitive flexible porous sensor.

[0112] The process parameters include: nozzle diameter is 0.4mm; nozzle temperature is 240℃; printing speed is 20mm / s; base plate temperature is 100℃; layer thickness is 0.2mm; filling path is concentric circle filling, and the filling rate is 100%.

[0113] The sensor body of the finally obtained highly sensitive flexible porous sensor is a 5-layer composite material formed by stacking multiple fuses up and down; the fuses in any layer of the sensor body are arranged in parallel; interlayer pores are formed between any two adjacent layers of fuses in the sensor body, and the equivalent circular diameter of the interlayer pores is 0.05 mm; there are micropores inside and on the surface of the fuse, the micropores are spindle-shaped, and the volume of the micropores accounts for 20% of the volume of the fuse; the equivalent circular diameter of the micropores in the fuse formed by the composite material system A is 30-50 μm, and the equivalent circular diameter of the micropores in the fuse formed by the composite material system B is 35-60 μm; the fuse comprises a polymer matrix and a conductive filler, and the conductive filler is uniformly distributed in the polymer matrix to form a conductive network; the strain response sensitivity of the high-sensitive flexible porous sensor is 100, the temperature response sensitivity is 0.4% / ℃, the humidity response sensitivity is 1.3, the response sensitivity of chloroform is 0.8 (100ppm), the response sensitivity of methanol is 1 (100ppm), the response sensitivity of acetone is 0.9 (100ppm), the response sensitivity of ether is 1.1 (100ppm), and the response sensitivity of hexane is 2.1 (100ppm).

[0114] Example 3

[0115] A 3D printing preparation method for a highly sensitive flexible porous sensor, the specific steps are as follows:

[0116] (1) Preparation of raw materials:

[0117] The composite material system A includes a polymer matrix A, a conductive filler A and 5 wt% of a foaming agent A; wherein the mass ratio of the polymer matrix A to the conductive filler A is 7:3;

[0118] The composite material system B includes a polymer matrix B, a conductive filler B and 10 wt % of a foaming agent B; wherein the mass ratio of the polymer matrix B to the conductive filler B is 9:1;

[0119] Polymer matrix A: polyolefin thermoplastic elastomer, manufacturer: ExxonMobil, product number: POE 0203;

[0120] Polymer matrix B: polyvinylidene fluoride, manufacturer: Shanghai San Ai Fu New Materials Co., Ltd., product number: FR906;

[0121] Conductive filler A: graphene, manufacturer: Sane Chemical Technology (Shanghai) Co., Ltd., product number: A60116;

[0122] Conductive filler B: gold nanowire, manufacturer: Xianfeng Nano, product number: 103667;

[0123] Foaming agent A: AC foaming agent, manufacturer: Shanghai McLean Biochemical Technology Co., Ltd., CAS: 123-77-3;

[0124] Foaming agent B: thermal expansion microspheres, manufacturer: American Boliken, product number: 220DU30;

[0125] (2) Using melt 3D printing technology, two composite materials are melt-extruded from two spinnerets of a two-component spinneret to form parallel composite fuses, which are stacked up and down to obtain a sensor body. Wires are connected at both ends of the sensor body to form a highly sensitive flexible porous sensor.

[0126] The process parameters include: nozzle diameter is 0.6mm; nozzle temperature is 270℃; printing speed is 30mm / s; base plate temperature is 150℃; layer thickness is 0.3mm; filling path is linear filling; filling angle is 0°, and filling rate is 60%.

[0127] The sensor body of the finally obtained highly sensitive flexible porous sensor is a three-layer composite material formed by stacking multiple fuses up and down; the fuses in any layer of the sensor body are arranged in parallel; interlayer pores are formed between any two adjacent layers of fuses in the sensor body, and the equivalent circular diameter of the interlayer pores is 0.12 mm; there are micropores inside and on the surface of the fuse, the micropores are spindle-shaped, and the volume of the micropores accounts for 16% of the volume of the fuse; the equivalent circular diameter of the micropores in the fuse formed by the composite material system A is 50-70 μm, and the equivalent circular diameter of the micropores in the fuse formed by the composite material system B is 60-8 5μm; the fuse comprises a polymer matrix and a conductive filler, and the conductive filler is uniformly distributed in the polymer matrix to form a conductive network; the strain response sensitivity of the high-sensitivity flexible porous sensor is 123, the temperature response sensitivity is 0.5% / ℃, the humidity response sensitivity is 1.5, the response sensitivity of chloroform is 4 (500ppm), the response sensitivity of methanol is 3 (500ppm), the response sensitivity of acetone is 3.1 (500ppm), the response sensitivity of ether is 2.7 (500ppm), and the response sensitivity of hexane is 3.6 (500ppm).

[0128] Example 4

[0129] A 3D printing preparation method for a highly sensitive flexible porous sensor, the specific steps are as follows:

[0130] (1) Preparation of raw materials:

[0131] The composite material system A comprises a polymer matrix A, a conductive filler A and 10 wt% of a foaming agent A; wherein the mass ratio of the polymer matrix A to the conductive filler A is 9:1;

[0132] The composite material system B includes a polymer matrix B, a conductive filler B and 20 wt% of a foaming agent B; wherein the mass ratio of the polymer matrix B to the conductive filler B is 7:3;

[0133] Polymer matrix A: polystyrene elastomer, manufacturer: Li Changrong (Huizhou) High-tech Materials Co., Ltd., product number: SBS1475;

[0134] Polymer matrix B: polylactic acid, manufacturer: BASF, Germany, product number: Ultrafuse;

[0135] Conductive filler A: expanded graphite, manufacturer: Sane Chemical Technology (Shanghai) Co., Ltd., product number: A62064;

[0136] Conductive filler B: expanded graphite, manufacturer: Sane Chemical Technology (Shanghai) Co., Ltd., product number: A62064;

[0137] Foaming agent A: thermal expansion microspheres, manufacturer: American Boliken, product number: 220DU30;

[0138] Foaming agent B: AC foaming agent, manufacturer: Shanghai McLean Biochemical Technology Co., Ltd., CAS: 123-77-3;

[0139] (2) Using melt 3D printing technology, two composite materials are melt-extruded from two spinnerets of a two-component spinneret to form parallel composite fuses, which are stacked up and down to obtain a sensor body. Wires are connected at both ends of the sensor body to form a highly sensitive flexible porous sensor.

[0140] The process parameters include: nozzle diameter is 0.8mm; nozzle temperature is 180℃; printing speed is 40mm / s; base plate temperature is 60℃; layer thickness is 0.4mm; filling path is linear filling; filling angle is 45°, and filling rate is 40%.

[0141] The sensor body of the finally prepared highly sensitive flexible porous sensor is a three-layer composite material formed by stacking multiple fuses up and down; the fuses in any layer of the sensor body are arranged in parallel; interlayer pores are formed between any two adjacent layers of fuses in the sensor body, and the equivalent circular diameter of the interlayer pores is 0.15 mm; there are micropores inside and on the surface of the fuse, the micropores are spindle-shaped, and the volume of the micropores accounts for 60% of the volume of the fuse; the equivalent circular diameter of the micropores in the fuse formed by the composite material system A is 110-150 μm, and the equivalent circular diameter of the micropores in the fuse formed by the composite material system B is 100 ~130μm; the fuse comprises a polymer matrix and a conductive filler, the conductive filler is uniformly distributed in the polymer matrix and forms a conductive network; the strain response sensitivity of the high-sensitivity flexible porous sensor is 480, the temperature response sensitivity is 0.75% / ℃, the humidity response sensitivity is 3, the response sensitivity of chloroform is 5 (1000ppm), the response sensitivity of methanol is 4 (1000ppm), the response sensitivity of acetone is 2 (1000ppm), the response sensitivity of ether is 3 (1000ppm), and the response sensitivity of hexane is 4 (1000ppm).

[0142] Example 5

[0143] A 3D printing preparation method for a highly sensitive flexible porous sensor, the specific steps are as follows:

[0144] (1) Preparation of raw materials:

[0145] The composite material system A includes a polymer matrix A, a conductive filler, 15 wt% of a foaming agent and polyacrylonitrile fiber; wherein the mass ratio of the polymer matrix A to the conductive filler A is 8:2;

[0146] The composite material system B includes a polymer matrix B, a conductive filler, 5 wt% of a foaming agent and polyacrylonitrile fiber; wherein the mass ratio of the polymer matrix B to the conductive filler B is 8:2;

[0147] Polymer matrix A: polyether ester elastomer, manufacturer: DuPont, USA, product number: G3548L;

[0148] Polymer matrix B: polymethyl methacrylate, manufacturer: SABIC, product number: 20HR;

[0149] Conductive filler: graphene oxide, manufacturer: Sane Chemical Technology (Shanghai) Co., Ltd., product number: A60008;

[0150] Foaming agent: AC foaming agent, manufacturer: Shanghai McLean Biochemical Technology Co., Ltd., CAS: 123-77-3;

[0151] Polyacrylonitrile fiber: Manufacturer: Shandong Taili Chemical Fiber Products Co., Ltd., Item No.: White-6mm;

[0152] (2) Using the melt 3D printing technology, the two composite materials are melted and extruded from the two spinnerets of the two-component spinneret to form parallel composite fuses. The fuses are stacked up and down to obtain the sensor body. The two ends of the sensor body are connected with wires, such as Figure 1 As shown, the wire 2 is connected to both ends of the sensor body 1 through the conductive tape 3 to form a highly sensitive flexible porous sensor; wherein the amount of polyacrylonitrile fiber added is 0.5wt% of the fuse;

[0153] The process parameters include: nozzle diameter is 0.8mm; nozzle temperature is 210℃; printing speed is 30mm / s; base plate temperature is 100℃; layer thickness is 0.4mm; filling path is linear filling; filling angle is 0 / 90°, and filling rate is 100%.

[0154] like Figure 7 As shown, after printing (melting) and extrusion, the foaming agent 8 foams smoothly and forms micropores 9 in the fuse.

[0155] like Figure 2 As shown, the sensor body in the finally obtained high-sensitivity flexible porous sensor is a 4-layer composite material formed by stacking multiple fuses 4 up and down; the fuses in any layer of the sensor body are arranged in parallel; interlayer pores are formed between any two adjacent layers of fuses in the sensor body, and the equivalent circular diameter of the interlayer pores is 0.1 mm; there are micropores 9 inside and on the surface of the fuse, and the micropores 9 are spindle-shaped, and the volume of the micropores accounts for 50% of the volume of the fuse; the equivalent circular diameter of the micropores in the fuse formed by the composite material system A is 70-80 μm, and the equivalent circular diameter of the micropores in the fuse formed by the composite material system B is 75-95 μm; the fuse comprises a polymer matrix A6 and a polymer matrix B 7. Conductive filler and polyacrylonitrile fiber, polyacrylonitrile is evenly distributed in the polymer matrix, and the conductive filler is evenly distributed in the polymer matrix to form a conductive network; the strain response sensitivity of the high-sensitivity flexible porous sensor is 350, the temperature response sensitivity is 0.9% / ℃, the humidity response sensitivity is 2, the response sensitivity of chloroform is 1.4 (500ppm), the response sensitivity of methanol is 2 (500ppm), the response sensitivity of acetone is 1.1 (500ppm), the response sensitivity of ether is 2 (500ppm), and the response sensitivity of hexane is 3.4 (500ppm).

[0156] like Figure 8 As shown here Figure 8 (a) A multilayer composite material is drawn for illustration only and does not represent the actual number of layers). The extruded fuses are deposited at 0° and 90° in an alternating manner, and interlayer pores 5 can be seen between the fuses. Micropores 9 formed by foaming of the foaming agent exist inside and on the surface of a single fuse.

[0157] like Fig. 9As shown, after being stretched, the holes 5 between the fuse layers and the micro-holes 9 within the fuse are both elongated along the stretching direction.

[0158] like Fig.10 As shown, after being stretched, the fuse is stretched and squeezed to produce deformation, the micropores 9 are stretched, and the distribution of the internal conductive filler 10 particles also changes accordingly. The change of the conductive path 11 leads to the change of the electrical signal.

[0159] like Fig.11 As shown, after the gas is adsorbed, the fuse is deformed (expanded), the distance between the micropores 9 increases, and the distance between the particles of the internal conductive filler 10 increases, so that the conductive path 11 changes, resulting in a signal change.

[0160] Example 6

[0161] A 3D printing preparation method for a highly sensitive flexible porous sensor, the specific steps are as follows:

[0162] (1) Preparation of raw materials:

[0163] The composite material system A includes a polymer matrix A, a conductive filler A, 20 wt% of a foaming agent A and polyacrylonitrile fiber; wherein the mass ratio of the polymer matrix A to the conductive filler A is 7:3;

[0164] The composite material system B includes a polymer matrix B, a conductive filler B, 1 wt% of a foaming agent B and polyacrylonitrile fiber; wherein the mass ratio of the polymer matrix B to the conductive filler B is 9:1;

[0165] Polymer matrix A: polyolefin thermoplastic elastomer, manufacturer: ExxonMobil, product number: POE 0203;

[0166] Polymer matrix B: polyvinylidene fluoride, manufacturer: Shanghai San Ai Fu New Materials Co., Ltd., product number: FR906;

[0167] Conductive filler A: graphene, manufacturer: Sane Chemical Technology (Shanghai) Co., Ltd., product number: A60116;

[0168] Conductive filler B: gold nanowire, manufacturer: Xianfeng Nano, product number: 103667;

[0169] Foaming agent A: AC foaming agent, manufacturer: Shanghai McLean Biochemical Technology Co., Ltd., CAS: 123-77-3;

[0170] Foaming agent B: thermal expansion microspheres, manufacturer: American Boliken, product number: 220DU30;

[0171] Polyacrylonitrile fiber: Manufacturer: Shandong Taili Chemical Fiber Products Co., Ltd., Item No.: White-6mm;

[0172] (2) Using melt 3D printing technology, two composite materials are melt-extruded from two spinnerets of a two-component spinneret to form parallel composite fuses, which are stacked up and down to obtain a sensor body. Wires are connected at both ends of the sensor body to form a highly sensitive flexible porous sensor; wherein the amount of polyacrylonitrile fiber added is 0.5 to 3 wt% of the fuse;

[0173] The process parameters include: nozzle diameter is 0.8mm; nozzle temperature is 270℃; printing speed is 20mm / s; base plate temperature is 150℃; layer thickness is 0.4mm; filling path is concentric circle filling; filling rate is 80%.

[0174] The sensor body of the finally obtained highly sensitive flexible porous sensor is a three-layer composite material formed by stacking multiple fuses up and down; the fuses in any layer of the sensor body are arranged in parallel; interlayer pores are formed between any two adjacent layers of fuses in the sensor body, and the equivalent circular diameter of the interlayer pores is 0.15 mm; there are micropores inside and on the surface of the fuse, the micropores are spindle-shaped, and the volume of the micropores accounts for 54% of the volume of the fuse; the equivalent circular diameter of the micropores in the fuse formed by the composite material system A is 120-135 μm, and the equivalent circular diameter of the micropores in the fuse formed by the composite material system B is 110-120 μm; the fuse contains polymer The invention relates to a polymer sensor comprising a matrix, a conductive filler and polyacrylonitrile fibers, wherein the polyacrylonitrile is uniformly distributed in the polymer matrix, and the conductive filler is uniformly distributed in the polymer matrix to form a conductive network; the strain response sensitivity of the high-sensitivity flexible porous sensor is 500, the temperature response sensitivity is 1% / °C, the humidity response sensitivity is 2.6, the response sensitivity of chloroform is 4.8 (500ppm), the response sensitivity of methanol is 3.5 (500ppm), the response sensitivity of acetone is 1.6 (500ppm), the response sensitivity of ether is 2.5 (500ppm), and the response sensitivity of hexane is 4.4 (500ppm).

Claims

1. A highly sensitive flexible porous sensor, comprising a sensor body, with wires connected to both ends of the sensor body, characterized in that: The sensor body is a multi-layer composite material formed by stacking multiple fuses up and down; The fuses are arranged in parallel in any layer of the sensor body; An interlayer hole is formed between any two adjacent layers of fuses of the sensor body; The fuse has micropores inside and on the surface; The fuse comprises a polymer matrix and a conductive filler, wherein the conductive filler is evenly distributed in the polymer matrix and forms a conductive network; A polymer matrix refers to a polymer that can undergo volume changes when external conditions change.

2. A highly sensitive flexible porous sensor according to claim 1, characterized in that: The equivalent circular diameter of the interlayer pores is 0.05-0.15 mm, and the micropores are spindle-shaped, with an equivalent circular diameter of 10-150 μm.

3. A highly sensitive flexible porous sensor according to claim 1, characterized in that: The polymer matrix is ​​thermoplastic polyurethane, thermoplastic polyester elastomer, polyolefin thermoplastic elastomer, polystyrene elastomer, polyether ester elastomer, polyamide elastomer, polyvinylidene fluoride, polylactic acid, polymethyl methacrylate or polyvinyl alcohol; the conductive filler is carbon black, multi-walled carbon nanotubes, graphene, expanded graphite, graphene oxide, carbon fiber, nano silver wire or nano gold wire.

4. A highly sensitive flexible porous sensor according to claim 1, characterized in that: The mass ratio of the polymer matrix to the conductive filler is 9:1 to 7:3; the volume of the micropores accounts for 10 to 60% of the volume of the fuse.

5. The highly sensitive flexible porous sensor according to claim 1, characterized in that: The fuse is a parallel composite fuse; the fuse also contains polyacrylonitrile fibers, which are evenly distributed in a polymer matrix; and the addition amount of the polyacrylonitrile fibers is 0.5-3wt% of the fuse.

6. The method for preparing a highly sensitive flexible porous sensor according to claim 1, characterized in that: The composite material system is melted by using the melt 3D printing technology and then extruded from the spinneret to form a fuse. The fuse is stacked up and down to obtain the sensor body. The two ends of the sensor body are connected with wires to form a highly sensitive flexible porous sensor. The composite material system includes a polymer matrix, a conductive filler and a foaming agent.

7. The method for preparing a highly sensitive flexible porous sensor according to claim 6, characterized in that: The spinneret is a two-component spinneret; two composite material systems are melt-extruded from two spinneret holes of the two-component spinneret to form parallel composite fusible wires; The foaming agent is AC foaming agent or thermal expansion microspheres.

8. The method for preparing a highly sensitive flexible porous sensor according to claim 6, characterized in that: The added amount of the foaming agent is 0.5-20wt% of the composite material system.

9. The method for preparing a highly sensitive flexible porous sensor according to claim 6, characterized in that: The process parameters include: nozzle diameter is 0.4-0.8mm; nozzle temperature is 180-270℃; printing speed is 10-40mm / s; base plate temperature is 60-150℃; layer thickness is 0.2-0.4mm; filling path is linear filling or concentric circle filling; filling angle is 0°-90°.

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