Ion electron pressure sensor and manufacturing process thereof

Abstract

The invention relates to the technical field of pressure sensors, and discloses an ion electron pressure sensor and a manufacturing process thereof. The silkworm cocoon ionic gel layer is adhered to the bottom surface of the PU foam layer; the two gold electrodes are respectively arranged on the top surface of the PU foam layer and the bottom surface of the silkworm cocoon ionic gel layer; and composite material layers are adhered to the opposite surfaces of the two gold electrodes. According to the technical scheme of the invention, the natural porous structure of silkworm cocoons is utilized to prepare the silkworm cocoons into the ionic gel, and then the ionic liquid is stored in the ionic gel and is released when the pressure is applied, so that the capacitance value of the capacitor is instantly increased, and the sensitivity is improved; when the sensor is constructed by utilizing the pu foam, small initial capacitance is formed; due to the rough surfaces of the silkworm cocoons and the pu foam, the contact area of the electrode and the dielectric layer is gradually increased in the compression process; a shear thickening material is used as a packaging layer, and different from a common ion electron sensor, the obtained sensor also has an impact protection function.

Description

Technical Field

[0001] The present invention belongs to the technical field of pressure sensors, and specifically relates to an ion-electronic pressure sensor and its manufacturing process. Background Art

[0002] With the continuous development of sensor technology, pressure sensors are increasingly widely used in various fields. Especially in the fields of intelligent manufacturing, medical care, environmental monitoring, etc., the sensitivity and accuracy of pressure sensors play a crucial role in the performance of the system. Traditional pressure sensors generally adopt a capacitive structure, where pressure is used to change the shape or thickness of the dielectric layer to achieve capacitance changes, thereby reflecting pressure changes. However, this method often faces certain limitations in the process of improving sensitivity, mainly reflected in the selection of dielectric layer materials and structural design.

[0003] Currently, most capacitive pressure sensors use dielectric layer materials such as polymers, ceramics, or other synthetic materials. The electrical properties of these materials are relatively fixed and it is difficult to quickly respond to changes in external pressure, thereby affecting the sensitivity of the sensor. In addition, many existing technologies attempt to improve the sensitivity of the sensor by changing the surface structure of the dielectric layer or adding specific materials to its surface. However, such methods usually require complex processes or increase the manufacturing cost of the sensor, and it is difficult to achieve the expected sensitivity improvement effect in actual applications.

[0004] In recent years, researchers have begun to attempt to use natural materials in the design and manufacture of sensors. Among them, silkworm cocoons, as a material with a natural porous structure, have attracted wide attention due to their good biodegradability, flexibility, and the potential to obtain electrical properties through specific treatments. The silk fibroin in silkworm cocoons can be transformed into an ion gel material with good ion conductive properties after chemical treatment.

[0005] However, there is currently no technology on the market that directly applies silkworm cocoon ion gel to the dielectric layer of pressure sensors. When using pu foam to construct the sensor, the formation of its small initial capacitance; the rough surfaces of the silkworm cocoon and pu foam, resulting in a gradual increase in the contact area between the electrode and the dielectric layer during the compression process, etc. There is no use of stg (shear thickening material) as the encapsulation layer in the current technology. Different from general ion-electronic sensors, the finally obtained sensor also has an impact protection function. The design of this new type of sensor can effectively overcome the limitations of traditional technologies and has broad application prospects and market potential. Summary of the Invention

[0006] To solve the above technical problems, the basic concept of the technical solution adopted by the present invention is: An ionic electronic pressure sensor and its manufacturing process, including a PU foam layer; and a cocoon ionic gel layer adhered to the bottom surface of the PU foam layer; also including two gold electrodes respectively arranged on the top surface of the PU foam layer and the bottom surface of the cocoon ionic gel layer; on the opposite sides of the two gold electrodes, a composite material layer is adhered, and the composite material layer is a shear thickening gum (STG) / polydimethylsiloxane (PDMS) / nano-silica (NS) composite material layer.

[0007] As a preferred embodiment of the present invention, the present invention also discloses a preparation method of an ionic electronic pressure sensor, and the steps of the preparation method are as follows: Step S1: Gold is plated on the copper-clad side of the commercial PI-copper film for 4 minutes under the condition of a current of 25 mA by an ion sputtering instrument, which is used as the electrode layer of the ionic electronic pressure sensor, and conductive silver wires are pasted on the gold-plated layer by conductive silver paste to prepare external electrodes; Step S2: A PU foam with a thickness of 3 mm and a PPI of 60 and the prepared cocoon ionic gel are placed in the middle of the sensor as a dielectric layer; Step S3: Both ends of the sensor are covered with STG / PDMS / NS composite materials; Step S4: Finally, the sensor is encapsulated with a PI film to obtain an ionic electronic pressure sensor.

[0008] As a preferred embodiment of the present invention, the preparation method of the cocoon ionic gel includes the following steps: a: Cut the mulberry cocoons into a size of 2 cm * 2.5 cm (the specific size can be adjusted) and put them into an oven at 55 °C in advance for 24 h to remove moisture; b: Dissolve ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) with a purity of 98% in pure water to prepare an ionic liquid solution with a concentration of 3.5 g / ml; c: Put the cocoons into the ionic liquid solution and place them in an ultrasonic cleaner for ultrasonic treatment for 4 h, and then put them into an oven at 85 °C for treatment for 1.5 h; d: After taking out, absorb the excess ionic liquid solution with dust-free paper to obtain the cocoon ionic gel.

[0009] As a preferred embodiment of the present invention, the preparation process of the STG / PDMS / NS composite material is as follows: Step A: First, heat boric acid at 160 °C for 2 h to obtain pyroboric acid. Then, stir the pyroboric acid and dimethyl silicone oil with a mass ratio of 2:15 at 210 °C for 4 h. After cooling the mixture to room temperature, shear thickening gum is obtained; Step B: Weigh SiO2 nanoparticles, benzoyl peroxide as the vulcanizing agent, and the shear thickening glue prepared previously in a mass ratio of 2.5:1:25, stir them thoroughly in a certain amount of acetone and perform ultrasonic treatment for 30 min to prepare a SiO2 / shear thickening glue suspension; Step C: Add component A of the shear thickening glue to the SiO2 / shear thickening glue suspension, stir evenly with an overhead stirrer, and then place it in an AR-100 Nisshin-based rotary and orbital mixer for further stirring and defoaming; subsequently, place the suspension in a heating jacket at 60 °C for stirring treatment to volatilize the excess acetone; after a certain amount of acetone has volatilized, add component B of PDMS and perform stirring and defoaming treatment with a mixer; Step D: Place the treated suspension in an oven at 100 °C for vulcanization for 3 h; lay the vulcanized composite material flat in a mold with a thickness of 1 mm and perform hot pressing at 100 °C and 20 MPa for 15 min to obtain a composite material of shear thickening glue, PDMS, and nano-SiO2.

[0010] The present invention has the following beneficial effects compared with the prior art: The technical solution of the present invention utilizes the natural porous structure of silkworm cocoons, and then prepares them into ionic gels and stores ionic liquids in them and releases them during pressure application, improving the effective dielectric constant of the dielectric layer, thereby instantaneously increasing the capacitance value of the capacitor and improving its sensitivity.

[0011] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings. Description of the Drawings

[0012] In the drawings: Figure 1 It is a schematic diagram of the overall structure of an ion-electronic pressure sensor; Figure 2 It is a rheological property diagram of the composite material of the present invention; Figure 3 It is a sensing property diagram of the ion-electronic pressure sensor.

[0013] In the figure: 1, composite material layer; 2, gold electrode; 3, PU foam layer; 4, silkworm cocoon ionic gel layer. Specific Embodiments

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments in conjunction with the accompanying drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention.

[0015] As Figures 1 to 3As shown in the figure, an ion-electronic pressure sensor includes a PU foam layer 3; and a silkworm cocoon ion gel layer 4 adhered to the bottom surface of the PU foam layer 3. It also includes two gold electrodes 2 respectively arranged on the top surface of the PU foam layer 3 and the bottom surface of the silkworm cocoon ion gel layer 4. Composite material layers 1 are adhered to the opposite sides of the two gold electrodes 2. The composite material layer 1 is a shear thickening gel (STG) / polydimethylsiloxane (PDMS) / nano-silica (NS) composite material layer.

[0016] The present invention also discloses a preparation method of an ion-electronic pressure sensor. The steps of the preparation method are as follows: Step S1: Gold is sputtered on the copper-clad side of a commercial PI-copper thin film for 4 minutes at a current of 25 mA by an ion sputtering instrument to be used as the electrode layer of the ion-electronic pressure sensor. Conductive silver wires are pasted on the gold-plated layer with conductive silver paste to prepare external electrodes. Step S2: A PU foam with a thickness of 3 mm and a PPI of 60 and the prepared silkworm cocoon ion gel are placed in the middle of the sensor as a dielectric layer. Step S3: Both ends of the sensor are covered with a shear thickening gel (STG) / polydimethylsiloxane (PDMS) / nano-silica (NS) composite material. Step S4: Finally, the sensor is encapsulated with a PI film to obtain an ion-electronic pressure sensor.

[0017] Furthermore, the preparation method of the silkworm cocoon ion gel includes the following steps: a: Cut the mulberry silkworm cocoons into a size of 2 cm * 2.5 cm (the specific size can be adjusted) and put them into an oven at 55 °C for 24 h to remove moisture in advance. b: Dissolve ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) with a purity of 98% in pure water to prepare an ionic liquid solution with a concentration of 3.5 g / ml. c: Put the silkworm cocoons into the ionic liquid solution and place them in an ultrasonic cleaner for ultrasonic treatment for 4 h, and then place them in an oven at 85 °C for treatment for 1.5 h. d: After taking out, absorb the excess ionic liquid solution with dust-free paper to obtain the silkworm cocoon ion gel.

[0018] Furthermore, the preparation process of the shear thickening gel, PDMS, and nano-silica composite material is as follows: Step A: First, heat boric acid at 160 °C for 2 h to obtain pyroboric acid. Then, stir a mixture of pyroboric acid and dimethyl silicone oil with a mass ratio of 2:15 at 210 °C for 4 h. After cooling the mixture to room temperature, shear thickening gel is obtained. Step B: Weigh SiO2 nanoparticles, benzoyl peroxide as the vulcanizing agent, and the shear thickening gum prepared previously in a mass ratio of 2.5:1:25. Stir them well in a certain amount of acetone and perform ultrasonic treatment for 30 min to prepare a SiO2 / shear thickening gum suspension; Step C: Add component A of the shear thickening gum to the SiO2 / shear thickening gum suspension and stir evenly with a overhead stirrer. Then put it into an AR-100 Nisshinbo planetary mixer for further stirring and defoaming; Subsequently, place the suspension in a heating jacket at 60 °C for stirring treatment to volatilize the excess acetone; After a certain amount of acetone has volatilized, add component B of PDMS and perform stirring and defoaming treatment with a mixer; Step D: Place the treated suspension in an oven at 100 °C for vulcanization for 3 h; Lay the vulcanized composite material flat in a mold with a thickness of 1 mm and hot press it at 100 °C and 20 MPa for 15 min to obtain a composite material of shear thickening gum, PDMS, and nano-SiO2.

[0019] Traditional sensors usually adopt microstructures (such as micro pyramids, micro domes, gradient structures, etc.), which not only makes the cost and technical difficulty high, but also the microstructures will harden under high pressure, resulting in a decrease in sensitivity. Therefore, the novel double dielectric layer structure designed in this technical solution based on the compressibility of materials effectively avoids this problem and significantly improves the sensitivity and working pressure range of the sensor.

[0020] Due to the porous structures inside the silk cocoon ion gel and the PU foam, the contact area between the electrode and the dielectric layer gradually increases during the compression process. The sensitivity of the ion-electronic pressure sensor effectively increases because a double electron layer is formed at the contact interface between its electrode and the dielectric layer, thus significantly increasing the capacitance of the sensor (this is the inherent advantage of the ion-electronic pressure sensor). Therefore, compared with traditional sensors during the compression process, initially, since the ionic liquid in the silk cocoon ion gel has not penetrated into the gold electrode, that is, the double electron layer has not been formed (at this time, the initial capacitance is very small). As the pressure increases later, the double electron layer gradually forms, resulting in a significant increase in capacitance, thus significantly increasing the sensitivity of the sensor. Due to the synergistic effect between the silk cocoon ion gel and the PU foam, the sensor in this technical solution has a wide working range while having ultra-high sensitivity compared with other sensors.

Claims

1. An ion-electronic pressure sensor, characterized in that, Comprising: PU foam layer (3); Silkworm cocoon ion gel layer (4), adhered to the bottom surface of the PU foam layer (3); Gold electrodes (2), two in number, respectively arranged on the top surface of the PU foam layer (3) and the bottom surface of the silkworm cocoon ion gel layer (4); Composite material layers (1) are adhered to the opposite sides of the two gold electrodes (2).

2. An ion-electronic pressure sensor according to claim 1, characterized in that, The composite material layer (1) is a composite material layer of shear thickening glue, polydimethylsiloxane and nano-silica.

3. A preparation method of an ion-electronic pressure sensor, which is applied to an ion-electronic pressure sensor according to any one of claims 1-2, characterized in that, The preparation method steps are as follows: Step S1: Gold-plate the copper-clad side of a commercial PI-copper thin film for 4 min under the condition of a current of 25 mA by using an ion sputtering instrument, which is used as the electrode layer of the ion-electronic pressure sensor, and paste a conductive silver wire on the gold-plated layer by using conductive silver paste to prepare an external electrode; Step S2: Place a PU foam with a thickness of 3 mm and a PPI of 60 and the prepared silkworm cocoon ion gel in the middle of the sensor as the dielectric layer; Step S3: Cover both ends of the sensor with a composite material of shear thickening glue, polydimethylsiloxane and nano-silica; Step S4: Finally, encapsulate the sensor with a PI thin film to obtain an ion-electronic pressure sensor.

4. The preparation method of an ion-electronic pressure sensor according to claim 3, wherein, The preparation method of the silkworm cocoon ion gel includes the following steps: a: Cut the mulberry silkworm cocoon into a size of 2 cm * 2.5 cm and put it into an oven at 55 °C in advance for 24 h to remove moisture; b: Dissolve the ionic liquid 1-butyl-3-methylimidazolium chloride with a purity of 98% in pure water to prepare an ionic liquid solution with a concentration of 3.5 g / ml; c: Put the silkworm cocoon into the ionic liquid solution and put it into an ultrasonic cleaner for ultrasonic treatment for 4 h, and then put it into an oven at 85 °C for treatment for 1.5 h; d: After taking it out, absorb the excess ionic liquid solution with lint-free paper to obtain the silkworm cocoon ion gel.

5. The preparation method of an ion-electronic pressure sensor according to claim 3, characterized in that, The preparation process of the composite material of shear thickening glue, polydimethylsiloxane and nano-silica is as follows: Step A: First, heat boric acid at 160 °C for 2 h to obtain pyroboric acid. Then stir the pyroboric acid and dimethyl silicone oil with a mass ratio of 2:15 at 210 °C for 4 h. After cooling the mixture to room temperature, shear thickening glue is obtained; Step B: Weigh SiO2 nanoparticles, vulcanizing agent benzoyl peroxide, and the shear thickening glue prepared in the previous stage with a mass ratio of 2.5:1:25, and fully stir and ultrasonically treat them in a certain amount of acetone for 30 min to prepare a SiO2 / shear thickening glue suspension; Step C: Add the A component of the shear thickening glue to the SiO2 / shear thickening glue suspension and stir it evenly with a overhead stirrer, then put it into an AR-100 Nissin base self-rotating and revolving stirrer for further stirring and defoaming; then place the suspension in a heating jacket at 60 °C for stirring treatment to volatilize the excess acetone; after a certain amount of acetone has volatilized, add the B component of PDMS and stir and defoam it with a stirrer; Step D: Place the treated suspension in an oven at 100 °C for vulcanization for 3 h; lay the vulcanized composite material flat in a mold with a thickness of 1 mm and hot press it at 100 °C and 20 MPa for 15 min to obtain a composite material of shear thickening glue, polydimethylsiloxane and nano-silica.

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