WO2020191947A1 - Sensor dielectric layer and preparation method and use thereof - Google Patents

Sensor dielectric layer and preparation method and use thereof Download PDF

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Publication number
WO2020191947A1
WO2020191947A1 PCT/CN2019/094686 CN2019094686W WO2020191947A1 WO 2020191947 A1 WO2020191947 A1 WO 2020191947A1 CN 2019094686 W CN2019094686 W CN 2019094686W WO 2020191947 A1 WO2020191947 A1 WO 2020191947A1
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dielectric layer
porous material
sensor
optionally
porous membrane
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PCT/CN2019/094686
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French (fr)
Inventor
Chuanfei Guo
Qingxian LIU
Quan Wang
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Southern University Of Science And Technology.
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Publication of WO2020191947A1 publication Critical patent/WO2020191947A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators

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  • the present application belongs to the technical field of sensors, and relates to a sensor dielectric layer and a preparation method and a use thereof.
  • Sensors with various working principles can convert the changes of measured objects into electrical signals or other information in required forms and output them so as to meet the requirements of transmission, processing, storage, display, recording and control of the information, which therefore play a very important role in people's lives.
  • the capacitive pressure sensor that senses the external force depending on the change of the capacitance value has attracted extensive attention due to its simple structure, good stability and high sensitivity.
  • capacitive pressure sensors have been made remarkable progress in performance parameters such as flexibility, sensitivity, stability and detection limit by means of improving the structure of the sensor dielectric layer.
  • the fabrication of highly transparent pressure sensors still faces enormous challenges, of which the main reason is that maintaining high transparency and high sensing performance at the same time is contradictory for the same sensor dielectric layer.
  • the sensors having a general highly transparent material such as polydimethylsiloxane, polyester, polyimide and glass as the dielectric layer show low sensitivity, which affects their practical application; while the dielectric layer having porous structure or surface microstructure seriously reduces the transparency of the entire device although it can improve the sensitivity of the sensor.
  • the preparation of a highly transparent and highly sensitive dielectric layer is of great importance for the production of a highly transparent sensor.
  • CN105865667A discloses a capacitive flexible pressure sensor based on a microstructured dielectric layer and a method for fabricating the same.
  • the capacitive flexible pressure sensor comprises an upper flexible substrate and a lower flexible substrate, an upper conductive layer attached to an inner surface of the upper flexible substrate and a lower conductive layer attached to an inner surface of the lower flexible substrate, with a microstructured dielectric layer being disposed between the upper conductive layer and the lower conductive layer.
  • CN106017748A discloses a capacitive flexible pressure sensor based on a composite material dielectric layer and a method for fabricating the same.
  • the capacitive flexible pressure sensor comprises an upper flexible substrate and a lower flexible substrate, an upper conductive layer attached to an inner surface of the upper flexible substrate and a lower conductive layer attached to an inner surface of the lower flexible substrate, with a composite material dielectric layer being disposed between the upper conductive layer and the lower conductive layer.
  • the polymer resin of the dielectric layer is doped with materials including a metal conductor, a ferroelectric ceramic, a carbon material and an organic semi-conductor, thereby effectively improving the sensitivity of the capacitive flexible pressure sensor.
  • the invention achieves the purpose of improving the sensitivity of the device by the composite dielectric layer, similarly, it also fails to prepare a dielectric layer which is transparent and has high sensitivity.
  • CN109288500A disclosed a wearable garment sensor and preparation method and application thereof.
  • the garment sensor comprises a fabric layer, a first electrode layer, a dielectric layer and a second electrode layer successively from bottom to top; in which the dielectric layer has a porous structure and an ionic liquid is supported on a pore wall of the dielectric layer.
  • the sensor of this invention has poor transparency, which affects its application.
  • the purpose of the application is to provide a sensor dielectric layer and a preparation method and a use thereof.
  • the sensor dielectric layer provided by the present application can provide high sensitivity, is a transparent dielectric layer, can have flexibility, and is simple in preparation process, low-cost in raw materials, and favorable for large-scale industrial production.
  • the present application provides a sensor dielectric layer, wherein the dielectric layer comprises a porous material and an ionic conductor liquid filled in the pores of the porous material, and the porous material is a non-transparent or semi-transparent material.
  • the sensor dielectric layer has high sensitivity, good light transmittance, and can have flexibility.
  • the dielectric layer provided by the present application adopts a non-transparent or semi-transparent material, the ionic conductor liquid is uniformly distributed in the pores of the porous material, and the rough structure of the porous material surface itself is not completely filled. This unique approach can significantly increase the transparency of the non-transparent or semi-transparent porous material.
  • the coexistence of the ionic active solution and the microstructure can also allow to form an electric double layer in the sensor, thereby greatly improving the sensing performance of the sensor.
  • the non-transparent material refers to a material having a transparency of 0%
  • the semi-transparent material refers to a material having a transparency of not more than 10%
  • the term “comprise (s) /comprising” used in the present application means that in addition to the components described, other components which impart different properties to the cloth can also be included.
  • the term “comprise (s) /comprising” used in the present application may also be replaced by a closed description as “is/are/being” or “consist (s) of/consisting of” ..
  • the porous material is a flexible material.
  • the porous material comprises any one selected from the group consisting of a cloth, a paper, a plastic foam, a polyimide porous membrane, a polydimethylsiloxane porous membrane, a polyvinylidene fluoride porous membrane, a polystyrene porous membrane, a polylactic acid porous membrane, a polypropylene porous membrane, a polyvinyl chloride porous membrane, a polyethylene porous membrane, a cellulose porous membrane, a cellulose acetate porous membrane and a nitrocellulose porous membrane, or a combination of at least two selected therefrom.
  • the typical but non-limiting combinations include: a combination of a cloth and a paper, a combination of a plastic foam and a polyimide porous membrane, a combination of a polydimethylsiloxane porous membrane and a polyvinylidene fluoride porous membrane, a combination of a polystyrene porous membrane, a polylactic acid porous membrane and a polypropylene porous membrane, a combination of a polyvinyl chloride porous membrane, a polyethylene porous membrane and a cellulose acetate porous membrane, a combination of a cloth, a paper, a plastic foam and a polyimide porous membrane, a combination of a polydimethylsiloxane porous membrane, a polyvinylidene fluoride porous membrane, a polystyrene porous membrane, a cellulose porous membrane, a polylactic acid porous membrane and a polypropylene porous membrane, a combination of a polyimide porous membrane
  • the porous material has a pore size of 0.01-100 ⁇ m. for example 0.01 ⁇ m, 1 ⁇ m, 5 ⁇ m, 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, 100 ⁇ m and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable, optionally 0.1-10 ⁇ m, optionally 5 ⁇ m.
  • the porous material has a thickness of 0.01-100 mm, for example 0.01 mm, 1 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable, optionally 0.1-10 mm, optionally 0.5 mm.
  • the porous material has a porosity of 10%-99%, for example 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable, optionally 30-80%, optionally 60%.
  • the ionic conductor liquid comprises any one selected from the group consisting of an ionic liquid, a sodium salt solution, a potassium salt solution, a sulphate solution, a nitrate solution, a chloride salt solution and a phosphate solution, or a combination of at least two selected therefrom, wherein the typical but non-limiting combinations include: a combination of an ionic liquid and a sodium salt solution, a combination of a potassium salt solution and a sulphate solution, a combination of a nitrate solution and a chloride salt solution, a combination of an ionic liquid, a sodium salt solution and a potassium salt solution, a combination of a sulphate solution, a nitrate solution and a chloride salt solution, a combination of an ionic liquid, a sodium salt solution, a potassium salt solution and sulphate solution, a combination of a nitrate solution, a chloride salt solution, a combination of an ionic liquid, a sodium salt solution,
  • the ionic conductor liquid is an ionic liquid.
  • the ionic liquid includes, but is not limited to, any one selected from the group consisting of 1-butyl-3-methylimidazolium trifluoroacetate, 1-hexyl-3-methylimidazolium chloride, 1-amyl-3-methylimidazolium bromide, tributylmethylammonium chloride and 1-ethyl-3-methylimidazolium hexafluorophosphate, or a combination of at least two selected therefrom.
  • the solvent in the sodium salt solution, potassium salt solution, sulphate solution, nitrate solution, chloride salt solution or phosphate solution can be water.
  • the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: (0.1-10) .
  • too much ionic conductor liquid and too little porous material in the dielectric layer may result in poor mechanical properties of the membrane; while too much porous material and too little ionic conductor liquid may result in low transparency and poor sensing performance.
  • the present application provides a preparation method of the sensor dielectric layer according to the first aspect, which preparation method comprises the following steps:
  • the preparation method provided by the present application is simple and practicable, low-cost in raw materials, and convenient for large-scale industrial production.
  • the means for mixing the ionic conductor liquid with the porous material comprises any one selected from the group consisting of suction filtration, titration, spray coating, coating, and immersion, or a combination of at least two selected therefrom, wherein the typical but non-limiting combinations include: a combination of suction filtration and titration, a combination of spray coating and coating, a combination of suction filtration, titration and spray coating, a combination of suction filtration, titration, spray coating and coating, a combination of suction filtration, titration, spray coating, coating and immersion, optionally immersion.
  • the surface of the porous material still has a part of protruding structure, and the sensitivity of the sensor can be effectively improved by the combined action of the protruding structure and the ion conductor.
  • the time for the standing is 1-120 min, for example 1 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable, optionally 10-60 min, optionally 30 min.
  • the preparation method further comprises removing the excess ionic conductor liquid on the surface of the porous material after the standing.
  • the means for removing the excess ionic conductor liquid on the surface of the porous material comprises any one selected from the group consisting of inversion standing, dust-free cloth wiping, glass rod roll wiping, oscillation and rotation, or a combination of at least two selected therefrom, wherein the typical but non-limiting combinations include: a combination of inversion standing and dust-free cloth wiping, a combination of glass rod roll wiping and oscillation, a combination of dust-free cloth wiping, glass rod roll wiping and oscillation, a combination of glass rod roll wiping, oscillation and, a combination of inversion standing, dust-free cloth wiping, glass rod roll wiping, oscillation and rotation.
  • the method comprises the following steps:
  • the present application provides a use of the sensor dielectric layer according to the first aspect, wherein the sensor dielectric layer is used in a flexible transparent sensor.
  • the dielectric layer provided by the present application not only has good optical transparency and flexibility, but also provides high sensing performance, and the dielectric layer has a large application space in the manufacture of transparent sensor devices.
  • the present application has the following beneficial effects:
  • the dielectric layer is mainly composed of a non-transparent or semi-transparent porous material and an ionic conductor liquid. Since the ionic conductor liquid has a similar refractive index to the porous material, the ionic conductor liquid loaded in the pores of the porous material may significantly improve the transparency of the membrane, thereby transforming the non-transparent or semi-transparent porous membrane material into a highly transparent dielectric material, achieving the purpose of converting the non-transparent material into a transparent material;
  • the ionic active material present in the pores of the porous material canlead to form an electric double layer in the sensor under the action of an external force, thereby improving the sensing performance of the sensor;
  • the sensor dielectric layer provided by the present application has a transmissivity that can reach 96.1%, a detection limit that can be as low as 0.2 Pa, a response time that can be as low as 32 s, and a maximum sensitivity that can reach 2.825 KPa -1 , and can be applied in fabrication of highly transparent sensors.
  • Fig. 1 is a schematic structural view of the sensor dielectric layer according to Example 1 of the present application, wherein: 1 -porous material, 2 -ionic conductor liquid;
  • Fig. 2 is a scanning electron micrograph of the polyvinylidene fluoride porous membrane used in Example 1 of the present application;
  • Fig. 3 is a scanning electron micrograph of the ionic liquid-loaded polyvinylidene fluoride membrane prepared in Example 1 of the present application;
  • Fig. 4 is a comparison diagram of transparency of the polyvinylidene fluoride porous membrane used and a dielectric layer filled with an ionic liquid in Example 1 of the present application;
  • Fig. 5 is a detection limit test diagram of a pressure sensor fabricated from the dielectric layer provided by Example 1 of the present application;
  • Fig. 6 is a response time test diagram of a pressure sensor fabricated from the dielectric layer provided by Example 1 of the present application, two embedded illustrations are enlarged figures showing data points when applying and removing pressure.
  • Fig. 7 is a sensitivity test diagram of a pressure sensor fabricated from the dielectric layer provided by Example 1 of the present application;
  • Fig. 8 is a sensitivity test diagram of a pressure sensor fabricated from the dielectric layer provided by Comparison Example 1.
  • a sensor dielectric layer was prepared according to the following method:
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinylidene fluoride porous membrane, the ionic conductor liquid is an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 1.
  • the morphology of the sensor dielectric layer prepared in this example was analyzed by scanning electron microscopy:
  • Fig. 1 is a schematic structural view of the sensor dielectric layer prepared according to this example. As shown in the figure, the ionic conductor liquid 2 fills the pores of the porous material 1.
  • Fig. 2 is a scanning electron micrograph of the polyvinylidene fluoride porous membrane used in this example.
  • the polyvinylidene fluoride before loading the ionic liquid, the polyvinylidene fluoride has a porous structureand a rough surface, and has high light-scattering ability, thus the porous polyvinylidene fluoride is non-transparent or semi-transparent.
  • Fig. 3 is a scanning electron micrograph of the ionic liquid-loaded polyvinylidene fluoride membrane prepared in this example.
  • the ionic liquid fills the pores of the polyvinylidene fluoride porous membrane, and the roughness of the membrane is lowered, so that the transparency of the membrane is greatly improved.
  • the surface of the membrane still has a part of a protruding structure, and the sensitivity of the sensor can be effectively improved by the combined action of the protruding structure and the ion conductor.
  • Fig. 4 is a comparison diagram of transparency of the polyvinylidene fluoride porous membrane used and the dielectric layer filled with an ionic liquid in this example. As can be seen from the figure, after being filled with the ionic liquid, the transmissivity of the polyvinylidene fluoride porous membrane is increased from 20.8%to 94.8%, and the transparency is greatly increased.
  • Fig. 5 is a detection limit test diagram of a pressure sensor fabricated from the dielectric layer provided by this example. As can be inferred from the figure, when the applied pressure is as small as 0.2 Pa, it can also have a distinct detection peak.
  • Fig. 6 is a response time test diagram of a pressure sensor fabricated from the dielectric layer provided by this example. As can be seen from the figure and the illustrations embedded therein, the response time can reach 40 ms, which is comparable to the sensing ability of human skin.
  • Fig. 7 is a sensitivity test diagram of a pressure sensor fabricated from the dielectric layer provided by this example. As can be seen from the figure, the maximum sensitivity of the sensor prepared from the dielectric layer provided in this example reaches 1.194 KPa -1 .
  • a sensor dielectric layer was prepared according to the following method:
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a non-transparent cloth, the ionic conductor liquid is an aqueous solution of sodium chloride, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 2.
  • a sensor dielectric layer was prepared according to the following method:
  • potassium salt potassium chloride
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a non-transparent plastic foam, the ionic conductor liquid is an aqueous solution of potassium chloride, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 0.2.
  • a sensor dielectric layer was prepared according to the following method:
  • a polystyrene porous membrane with a pore size of 1 ⁇ m, a porosity of 70%, a thickness of 0.1 mm was immersed in an aqueous solution of a nitrate (sodium nitrate) , and allowed to stand for 30 min;
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polystyrene porous membrane, the ionic conductor liquid is an aqueous solution of sodium nitrate, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 3.
  • a sensor dielectric layer was prepared according to the following method:
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polylactic acid porous membrane, the ionic conductor liquid is an aqueous solution of sodium sulphate, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 2.
  • a sensor dielectric layer was prepared according to the following method:
  • an ionic liquid (1-butyl-3-methylimidazolium trifluoroacetate) was filtered into a polypropylene porous membrane with a pore diameter of 100 ⁇ m, a porosity of 70%and a thickness of 3 mm, and allowed to stand for 60 min;
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polypropylene porous membrane, the ionic conductor liquid is an ionic liquid (1-butyl-3-methylimidazolium trifluoroacetate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 5.
  • a sensor dielectric layer was prepared according to the following method:
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinyl chloride porous membrane, the ionic conductor liquid is an aqueous solution of sodium phosphate, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 10.
  • a sensor dielectric layer was prepared according to the following method:
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyethylene porous membrane, the ionic conductor liquid is an aqueous solution of barium chloride, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 3.
  • a sensor dielectric layer was prepared according to the following method:
  • a cellulose acetate porous membrane with a pore size of 0.5 ⁇ m, a porosity of 80%, a thickness of 0.2 mm was immersed in an ionic liquid (1-amyl-3-methylimidazolium bromide) , and allowed to stand for 20 min;
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent cellulose acetate porous membrane, the ionic conductor liquid is an ionic liquid (1-amyl-3-methylimidazolium bromide) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 2.
  • a sensor dielectric layer was prepared according to a method of Example with the only difference is that the polyvinylidene fluoride porous membrane was replaced by a cellulose porous membrane in this example.
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent cellulose porous membrane, the ionic conductor liquid is an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 8.
  • a sensor dielectric layer was prepared according to the method of Example 1 with the only difference that the ionic liquid was replaced by an aqueous solution of a sodium salt (sodium chloride) in this example.
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinylidene fluoride porous membrane, the ionic conductor liquid is an aqueous solution of sodium chloride, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 1.
  • a sensor dielectric layer was prepared according to the following method:
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinylidene fluoride porous membrane, the ionic conductor liquid is an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 0.2.
  • the sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinylidene fluoride porous membrane, the ionic conductor liquid is an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 10.
  • Example 1 The only difference from Example 1 is that, in this comparison example, no ionic conductor liquid was filled.
  • Fig. 8 is a sensitivity test diagram of a pressure sensor fabricated from the dielectric layer provided by this comparison example. As can be seen from the figure, the maximum sensitivity of the device without being loaded with ionic conductor liquid is 0.245 KPa -1 . As can be seen in conjunction with Figures 7, 8 and 4, the loading of the ionic active material allows great increase of both transparency and sensing ability of the device.
  • Example 1 The only difference from Example 1 is that, in this comparison example, the ionic conductor liquid was replaced by purified water.
  • Example 1 The only difference from Example 1 is that, in the present comparison example, the polyvinylidene fluoride porous membrane was replaced by a glass.
  • Sensitivity test the required pressure was applied to the samples through a press machine, and the change of the capacitance value of the sample was recorded using a multi-function tester, wherein the test frequency is set to 1 ⁇ 10 5 Hz, and the detection limit, response time and sensitivity of the tested sample were calculated through the relationship between the force and the change rate of the capacitance value.
  • the sensor dielectric layers prepared in the examples of the present application have excellent optical transparency, and the sensor manufactured from the sensor dielectric layer has the advantages of low detection limit, fast response and high sensitivity.
  • the dielectric layer loaded with the ionic conductor liquid prepared by the present application can not only effectively improve the transparency of the device, but also significantly improve the sensing performance.
  • the use of a porous membrane as a substrate in the present application can better increase the sensing performance of the sensor.

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Abstract

A sensor dielectric layer and a preparation method and a use thereof. The sensor dielectric layer comprises a porous material (1) and an ionic conductor liquid (2) filled in the pores of the porous material (1), and the porous material (1) is a non-transparent or semi-transparent material. The preparation method comprises: mixing the ionic conductor liquid (2) with the porous material (1), allowing them to stand to obtain the sensor dielectric layer. By filling the ionic conductor liquid, the sensor dielectric layer achieves the purpose of converting a non-transparent material into a transparent material, improves the sensing performance of the sensor, and can be applied to the fabrication of a highly transparent sensor device or the like.

Description

Sensor Dielectric Layer and Preparation Method and Use Thereof Technical field
The present application belongs to the technical field of sensors, and relates to a sensor dielectric layer and a preparation method and a use thereof.
Background
Sensors with various working principles can convert the changes of measured objects into electrical signals or other information in required forms and output them so as to meet the requirements of transmission, processing, storage, display, recording and control of the information, which therefore play a very important role in people's lives. Among them, the capacitive pressure sensor that senses the external force depending on the change of the capacitance value has attracted extensive attention due to its simple structure, good stability and high sensitivity. In recent years, capacitive pressure sensors have been made remarkable progress in performance parameters such as flexibility, sensitivity, stability and detection limit by means of improving the structure of the sensor dielectric layer. At present, however, the fabrication of highly transparent pressure sensors still faces enormous challenges, of which the main reason is that maintaining high transparency and high sensing performance at the same time is contradictory for the same sensor dielectric layer. In other words, the sensors having a general highly transparent material such as polydimethylsiloxane, polyester, polyimide and glass as the dielectric layer show low sensitivity, which affects their practical application; while the dielectric layer having porous structure or surface microstructure seriously reduces the transparency of the entire device although it can improve the sensitivity of the sensor. On this basis, the preparation of a highly transparent and highly sensitive dielectric layer is of great importance for the production of a highly transparent sensor.
CN105865667A discloses a capacitive flexible pressure sensor based on a microstructured dielectric layer and a method for fabricating the same. The capacitive flexible pressure sensor comprises an upper flexible substrate and a lower flexible substrate, an upper conductive layer attached to an inner surface of the upper flexible substrate and a lower conductive layer attached to an inner  surface of the lower flexible substrate, with a microstructured dielectric layer being disposed between the upper conductive layer and the lower conductive layer. By designing parameters such as shape, size, distribution of the microstructure of the dielectric layer, the capacitive flexible pressure sensor of the invention realizes effective adjustment of the performance of the sensor and realizes the fabrication of the capacitive flexible pressure sensor with different sensitivity and test ranges. However, the construction of the microstructure inevitably increases the haze of the dielectric layer, reducing the overall transparency of the sensor, which affects the use range of the sensor.
CN106017748A discloses a capacitive flexible pressure sensor based on a composite material dielectric layer and a method for fabricating the same. The capacitive flexible pressure sensor comprises an upper flexible substrate and a lower flexible substrate, an upper conductive layer attached to an inner surface of the upper flexible substrate and a lower conductive layer attached to an inner surface of the lower flexible substrate, with a composite material dielectric layer being disposed between the upper conductive layer and the lower conductive layer. In this invention, the polymer resin of the dielectric layer is doped with materials including a metal conductor, a ferroelectric ceramic, a carbon material and an organic semi-conductor, thereby effectively improving the sensitivity of the capacitive flexible pressure sensor. Although the invention achieves the purpose of improving the sensitivity of the device by the composite dielectric layer, similarly, it also fails to prepare a dielectric layer which is transparent and has high sensitivity.
CN109288500A disclosed a wearable garment sensor and preparation method and application thereof. The garment sensor comprises a fabric layer, a first electrode layer, a dielectric layer and a second electrode layer successively from bottom to top; in which the dielectric layer has a porous structure and an ionic liquid is supported on a pore wall of the dielectric layer. Although better flexibility, the sensor of this invention has poor transparency, which affects its application.
Therefore, there is a need to develop a dielectric layer that is flexible and transparent and capable of providing high sensitivity so as to meet the requirements of highly transparent sensors.
Summary
The following is a brief summary of the subject matter that is described herein. The summary is not intended to be limiting as to the protection scope of the claims.
The purpose of the application is to provide a sensor dielectric layer and a preparation method and a use thereof. The sensor dielectric layer provided by the present application can provide high sensitivity, is a transparent dielectric layer, can have flexibility, and is simple in preparation process, low-cost in raw materials, and favorable for large-scale industrial production.
To achieve this purpose, the present application adopts the following technical solutions.
In a first aspect, the present application provides a sensor dielectric layer, wherein the dielectric layer comprises a porous material and an ionic conductor liquid filled in the pores of the porous material, and the porous material is a non-transparent or semi-transparent material.
In the present application, the sensor dielectric layer has high sensitivity, good light transmittance, and can have flexibility. Although the dielectric layer provided by the present application adopts a non-transparent or semi-transparent material, the ionic conductor liquid is uniformly distributed in the pores of the porous material, and the rough structure of the porous material surface itself is not completely filled. This unique approach can significantly increase the transparency of the non-transparent or semi-transparent porous material. Moreover, under the action of an external force, the coexistence of the ionic active solution and the microstructure can also allow to form an electric double layer in the sensor, thereby greatly improving the sensing performance of the sensor.
In the present application, the non-transparent material refers to a material having a transparency of 0%, and the semi-transparent material refers to a material having a transparency of not more than 10%.
As used herein, the term “comprise (s) /comprising” used in the present application means that in addition to the components described, other components which impart different properties to the cloth can also be included. In addition, the term “comprise (s) /comprising” used in the present application may also be replaced by a closed description as “is/are/being” or “consist (s) of/consisting of” ..
The following are preferred technical solutions of the present application, but not as a limit of technical solutions provided by the present application, and the technical objects and advantageous effects of the present application can be better achieved and realized by the following optional technical solutions.
As an optional technical solution of the present disclosure, the porous material is a flexible material.
Optionally, the porous material comprises any one selected from the group consisting of a cloth, a paper, a plastic foam, a polyimide porous membrane, a polydimethylsiloxane porous membrane, a polyvinylidene fluoride porous membrane, a polystyrene porous membrane, a polylactic acid porous membrane, a polypropylene porous membrane, a polyvinyl chloride porous membrane, a polyethylene porous membrane, a cellulose porous membrane, a cellulose acetate porous membrane and a nitrocellulose porous membrane, or a combination of at least two selected therefrom. Wherein the typical but non-limiting combinations include: a combination of a cloth and a paper, a combination of a plastic foam and a polyimide porous membrane, a combination of a polydimethylsiloxane porous membrane and a polyvinylidene fluoride porous membrane, a combination of a polystyrene porous membrane, a polylactic acid porous membrane and a polypropylene porous membrane, a combination of a polyvinyl chloride porous membrane, a polyethylene porous membrane and a cellulose acetate porous membrane, a combination of a cloth, a paper, a plastic foam and a polyimide porous membrane, a combination of a polydimethylsiloxane porous membrane, a polyvinylidene fluoride porous membrane, a polystyrene porous membrane, a cellulose porous membrane, a polylactic acid porous membrane and a polypropylene porous membrane, a combination of a polyimide porous membrane, a polydimethylsiloxane porous membrane, a polyvinyl chloride porous membrane, a polyethylene porous membrane, a cellulose porous membrane, a cellulose acetate porous membrane and a nitrocellulose porous membrane, and the like. Optionally, the porous material is a polyvinylidene fluoride porous membrane.
Optionally, the porous material has a pore size of 0.01-100 μm. for example 0.01 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable, optionally 0.1-10 μm, optionally 5μm.
Optionally, the porous material has a thickness of 0.01-100 mm, for example 0.01 mm, 1 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable, optionally 0.1-10 mm, optionally 0.5 mm.
Optionally, the porous material has a porosity of 10%-99%, for example 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable, optionally 30-80%, optionally 60%.
As an optional technical solution of the present application, the ionic conductor liquid comprises any one selected from the group consisting of an ionic liquid, a sodium salt solution, a potassium salt solution, a sulphate solution, a nitrate solution, a chloride salt solution and a phosphate solution, or a combination of at least two selected therefrom, wherein the typical but non-limiting combinations include: a combination of an ionic liquid and a sodium salt solution, a combination of a potassium salt solution and a sulphate solution, a combination of a nitrate solution and a chloride salt solution, a combination of an ionic liquid, a sodium salt solution and a potassium salt solution, a combination of a sulphate solution, a nitrate solution and a chloride salt solution, a combination of an ionic liquid, a sodium salt solution, a potassium salt solution and sulphate solution, a combination of a nitrate solution, a chloride salt solution, an ionic liquid and a phosphate solution, a combination of an ionic liquid, a sodium salt solution, a potassium salt solution, a sulphate solution and a nitrate solution, and the like; optionally an ionic liquid.
Optionally, the ionic conductor liquid is an ionic liquid. The ionic liquid includes, but is not limited to, any one selected from the group consisting of 1-butyl-3-methylimidazolium trifluoroacetate, 1-hexyl-3-methylimidazolium chloride, 1-amyl-3-methylimidazolium bromide, tributylmethylammonium chloride and 1-ethyl-3-methylimidazolium hexafluorophosphate, or a combination of at least two selected therefrom.
The solvent in the sodium salt solution, potassium salt solution, sulphate solution, nitrate solution, chloride salt solution or phosphate solution can be water.
As an optional technical solution of the present application, the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: (0.1-10) . for example 1: 0.1, 1: 0.5, 1: 1, 1: 2, 1: 3, 1: 4, 1: 5, 1: 6, 1: 7, 1: 8, 1: 9, 1: 10 and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable; optionally 1: (2-5) . In the present application, too much ionic conductor liquid and too little porous material in the dielectric layer may result in poor mechanical properties of the membrane; while too much porous material and too little ionic conductor liquid may result in low transparency and poor sensing performance.
In a second aspect, the present application provides a preparation method of the sensor dielectric layer according to the first aspect, which preparation method comprises the following steps:
mixing the ionic conductor liquid with the porous material, and allowing them to stand to obtain the sensor dielectric layer.
The preparation method provided by the present application is simple and practicable, low-cost in raw materials, and convenient for large-scale industrial production.
As an optional technical solution of the present application, the means for mixing the ionic conductor liquid with the porous material comprises any one selected from the group consisting of suction filtration, titration, spray coating, coating, and immersion, or a combination of at least two selected therefrom, wherein the typical but non-limiting combinations include: a combination of suction filtration and titration, a combination of spray coating and coating, a combination of suction filtration, titration and spray coating, a combination of suction filtration, titration, spray coating and coating, a combination of suction filtration, titration, spray coating, coating and immersion, optionally immersion.
After the ionic liquid is loaded on the porous material by the above method of the present application, the surface of the porous material still has a part of protruding structure, and the sensitivity of the sensor can be effectively improved by the combined action of the protruding structure and the ion conductor.
As an optional technical solution of the present application, the time for the standing is 1-120 min, for example 1 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min and the like, but not limited to the enumerated values recited herein, with the other unenumerated values within the range of the enumerated values being also applicable, optionally 10-60 min, optionally 30 min.
As an optional technical solution of the present application, the preparation method further comprises removing the excess ionic conductor liquid on the surface of the porous material after the standing.
Optionally, the means for removing the excess ionic conductor liquid on the surface of the porous material comprises any one selected from the group consisting of inversion standing, dust-free cloth wiping, glass rod roll wiping, oscillation and rotation, or a combination of at least two selected therefrom, wherein the typical but non-limiting combinations include: a combination of inversion standing and dust-free cloth wiping, a combination of glass rod roll wiping and oscillation, a combination of dust-free cloth wiping, glass rod roll wiping and oscillation, a combination of glass rod roll wiping, oscillation and, a combination of inversion standing, dust-free cloth wiping, glass rod roll wiping, oscillation and rotation.
As an optional technical solution of the preparation method according to the present application, the method comprises the following steps:
(1) mixing the ionic conductor liquid with the porous material by means of immersion, and allowing them to stand for 10-60 min;
(2) removing the excess ionic conductor liquid on the surface of the porous material in the step (1) by means of inversion standing to obtain the sensor dielectric layer.
In a third aspect, the present application provides a use of the sensor dielectric layer according to the first aspect, wherein the sensor dielectric layer is used in a flexible transparent sensor.
The dielectric layer provided by the present application not only has good optical transparency and  flexibility, but also provides high sensing performance, and the dielectric layer has a large application space in the manufacture of transparent sensor devices.
As compared to the existing technologies, the present application has the following beneficial effects:
(1) In the present application, the dielectric layer is mainly composed of a non-transparent or semi-transparent porous material and an ionic conductor liquid. Since the ionic conductor liquid has a similar refractive index to the porous material, the ionic conductor liquid loaded in the pores of the porous material may significantly improve the transparency of the membrane, thereby transforming the non-transparent or semi-transparent porous membrane material into a highly transparent dielectric material, achieving the purpose of converting the non-transparent material into a transparent material;
(2) In the present application, the ionic active material present in the pores of the porous material canlead to form an electric double layer in the sensor under the action of an external force, thereby improving the sensing performance of the sensor;
(3) The sensor dielectric layer provided by the present application has a transmissivity that can reach 96.1%, a detection limit that can be as low as 0.2 Pa, a response time that can be as low as 32 s, and a maximum sensitivity that can reach 2.825 KPa -1, and can be applied in fabrication of highly transparent sensors.
Other aspects will be apparent upon reading and understanding the detailed description and drawings.
Brief Description of the Drawings
Fig. 1 is a schematic structural view of the sensor dielectric layer according to Example 1 of the present application, wherein: 1 -porous material, 2 -ionic conductor liquid;
Fig. 2 is a scanning electron micrograph of the polyvinylidene fluoride porous membrane used in Example 1 of the present application;
Fig. 3 is a scanning electron micrograph of the ionic liquid-loaded polyvinylidene fluoride membrane prepared in Example 1 of the present application;
Fig. 4 is a comparison diagram of transparency of the polyvinylidene fluoride porous membrane used and a dielectric layer filled with an ionic liquid in Example 1 of the present application;
Fig. 5 is a detection limit test diagram of a pressure sensor fabricated from the dielectric layer provided by Example 1 of the present application;
Fig. 6 is a response time test diagram of a pressure sensor fabricated from the dielectric layer provided by Example 1 of the present application, two embedded illustrations are enlarged figures showing data points when applying and removing pressure.
Fig. 7 is a sensitivity test diagram of a pressure sensor fabricated from the dielectric layer provided by Example 1 of the present application;
Fig. 8 is a sensitivity test diagram of a pressure sensor fabricated from the dielectric layer provided by Comparison Example 1.
Detailed Description
In order to better illustrate the present application and to facilitate understanding of the technical solutions of the present application, the present application will be further described in detail below. However, the following examples are merely illustrative of the present application and are not intended to limit the scope of the present application, and the scope of the present application is defined by the claims.
The following are typical but non-limitative examples of the present application.
Example 1
In this example, a sensor dielectric layer was prepared according to the following method:
(1) a polyvinylidene fluoride porous membrane with a pore size of 5 μm, a porosity of 50%, a  thickness of 0.5 mm was immersed in an ionic liquid solution (1-ethyl-3-methylimidazolium hexafluorophosphate) , and allowed to stand for 60 min;
(2) the excess ionic conductor liquid on the surface of the membrane was removed by dust-free cloth wiping so as to obtain a transparent sensor dielectric layer.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinylidene fluoride porous membrane, the ionic conductor liquid is an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 1.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
The morphology of the sensor dielectric layer prepared in this example was analyzed by scanning electron microscopy:
Fig. 1 is a schematic structural view of the sensor dielectric layer prepared according to this example. As shown in the figure, the ionic conductor liquid 2 fills the pores of the porous material 1.
Fig. 2 is a scanning electron micrograph of the polyvinylidene fluoride porous membrane used in this example. As can be seen from the figure, before loading the ionic liquid, the polyvinylidene fluoride has a porous structureand a rough surface, and has high light-scattering ability, thus the porous polyvinylidene fluoride is non-transparent or semi-transparent.
Fig. 3 is a scanning electron micrograph of the ionic liquid-loaded polyvinylidene fluoride membrane prepared in this example. As can be seen from the figure, after immersion of the polyvinylidene fluoride porous membrane into the ionic liquid, the ionic liquid fills the pores of the polyvinylidene fluoride porous membrane, and the roughness of the membrane is lowered, so that the transparency of the membrane is greatly improved. Moreover, as a pressure sensor, after the  ionic liquid is loaded, the surface of the membrane still has a part of a protruding structure, and the sensitivity of the sensor can be effectively improved by the combined action of the protruding structure and the ion conductor.
Fig. 4 is a comparison diagram of transparency of the polyvinylidene fluoride porous membrane used and the dielectric layer filled with an ionic liquid in this example. As can be seen from the figure, after being filled with the ionic liquid, the transmissivity of the polyvinylidene fluoride porous membrane is increased from 20.8%to 94.8%, and the transparency is greatly increased.
Fig. 5 is a detection limit test diagram of a pressure sensor fabricated from the dielectric layer provided by this example. As can be inferred from the figure, when the applied pressure is as small as 0.2 Pa, it can also have a distinct detection peak.
Fig. 6 is a response time test diagram of a pressure sensor fabricated from the dielectric layer provided by this example. As can be seen from the figure and the illustrations embedded therein, the response time can reach 40 ms, which is comparable to the sensing ability of human skin.
Fig. 7 is a sensitivity test diagram of a pressure sensor fabricated from the dielectric layer provided by this example. As can be seen from the figure, the maximum sensitivity of the sensor prepared from the dielectric layer provided in this example reaches 1.194 KPa -1.
Example 2
In this example, a sensor dielectric layer was prepared according to the following method:
(1) an aqueous solution of sodium salt (sodium chloride) was titrated into a cloth with a pore size of 100 μm, a porosity of 30%, a thickness of 1 mm, and allowed to stand for 30 min;
(2) the excess aqueous solution of sodium salt on the surface of the cloth was removed by inversion standing so as to obtain a transparent dielectric layer material.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a  non-transparent cloth, the ionic conductor liquid is an aqueous solution of sodium chloride, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 2.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 3
In this example, a sensor dielectric layer was prepared according to the following method:
(1) an aqueous solution of potassium salt (potassium chloride) was coated into a plastic foam with a pore size of 50 μm, a porosity of 60%, a thickness of 10 mm, and allowed to stand for 20 min;
(2) the excess aqueous solution of potassium salt on the surface of the cloth was removed by glass rod roll wiping so as to obtain a transparent dielectric layer material.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a non-transparent plastic foam, the ionic conductor liquid is an aqueous solution of potassium chloride, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 0.2.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 4
In this example, a sensor dielectric layer was prepared according to the following method:
(1) a polystyrene porous membrane with a pore size of 1 μm, a porosity of 70%, a thickness of 0.1 mm was immersed in an aqueous solution of a nitrate (sodium nitrate) , and allowed to stand for 30 min;
(2) the excess aqueous solution of nitrate on the surface of the polystyrene porous membrane was  removed by oscillation so as to obtain a transparent dielectric layer material.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polystyrene porous membrane, the ionic conductor liquid is an aqueous solution of sodium nitrate, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 3.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 5
In this example, a sensor dielectric layer was prepared according to the following method:
(1) a polylactic acid porous membrane with a pore size of 10 μm, a porosity of 85%, a thickness of 0.3 mm was immersed in an aqueous solution of a sulphate (sodium sulphate) , and allowed to stand for 60 min;
(2) the excess aqueous solution of sulphate on the surface of the polylactic acid porous membrane was removed by rotation so as to obtain a transparent dielectric layer material.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polylactic acid porous membrane, the ionic conductor liquid is an aqueous solution of sodium sulphate, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 2.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 6
In this example, a sensor dielectric layer was prepared according to the following method:
(1) an ionic liquid (1-butyl-3-methylimidazolium trifluoroacetate) was filtered into a polypropylene porous membrane with a pore diameter of 100 μm, a porosity of 70%and a thickness of 3 mm, and allowed to stand for 60 min;
(2) the excess ionic gel on the surface of the polypropylene porous membrane was removed by dust-free cloth wiping so as to obtain a transparent dielectric layer material.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polypropylene porous membrane, the ionic conductor liquid is an ionic liquid (1-butyl-3-methylimidazolium trifluoroacetate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 5.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 7
In this example, a sensor dielectric layer was prepared according to the following method:
(1) an aqueous solution of a phosphate (sodium phosphate) was coated into a polyvinyl chloride porous membrane with a pore size of 50 μm, a porosity of 30%, a thickness of 5 mm, and allowed to stand for 60 min;
(2) the excess aqueous solution of phosphate on the surface of the polyvinyl chloride porous membrane was removed by oscillation so as to obtain a transparent dielectric layer material.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinyl chloride porous membrane, the ionic conductor liquid is an aqueous solution of sodium phosphate, and the mass ratio of the ionic conductor liquid to the porous  material in the sensor dielectric layer is 1: 10.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 8
In this example, a sensor dielectric layer was prepared according to the following method:
(1) an aqueous solution of a chloride salt (barium chloride) was suction-filtered into a polyethylene porous membrane with a pore diameter of 1 μm, a porosity of 40%, and a thickness of 1 mm, and allowed to stand for 120 minutes;
(2) the excess chloride salt solution on the surface of the polyethylene porous membrane was removed by rotation so as to obtain a transparent dielectric layer material.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyethylene porous membrane, the ionic conductor liquid is an aqueous solution of barium chloride, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 3.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 9
In this example, a sensor dielectric layer was prepared according to the following method:
(1) a cellulose acetate porous membrane with a pore size of 0.5 μm, a porosity of 80%, a thickness of 0.2 mm was immersed in an ionic liquid (1-amyl-3-methylimidazolium bromide) , and allowed to stand for 20 min;
(2) the excess ionic liquid on the surface of the cellulose acetate porous membrane was removed by  inversion standing so as to obtain a transparent dielectric layer material.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent cellulose acetate porous membrane, the ionic conductor liquid is an ionic liquid (1-amyl-3-methylimidazolium bromide) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 2.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 10
In this example, a sensor dielectric layer was prepared according to a method of Example with the only difference is that the polyvinylidene fluoride porous membrane was replaced by a cellulose porous membrane in this example.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent cellulose porous membrane, the ionic conductor liquid is an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 8.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 11
In this example, a sensor dielectric layer was prepared according to the method of Example 1 with the only difference that the ionic liquid was replaced by an aqueous solution of a sodium salt (sodium chloride) in this example.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic  conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinylidene fluoride porous membrane, the ionic conductor liquid is an aqueous solution of sodium chloride, and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 1.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 12
In this example, a sensor dielectric layer was prepared according to the following method:
(1) a polyvinylidene fluoride porous membrane with a pore size of 0.1 μm, a porosity of 80%, a thickness of 100 mm was immersed in an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and allowed to stand for 10 min;
(2) the excess ionic conductor liquid on the surface of the membrane was removed by dust-free cloth wiping so as to obtain a transparent sensor dielectric layer.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinylidene fluoride porous membrane, the ionic conductor liquid is an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 0.2.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Example 13
(1) a polyvinylidene fluoride porous membrane with a pore size of 0.01 μm, a porosity of 10%, a thickness of 0.01 mm was immersed in an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and allowed to stand for 1 min;
(2) the excess ionic conductor liquid on the surface of the membrane was removed by dust-free cloth wiping so as to obtain a transparent sensor dielectric layer.
The sensor dielectric layer prepared in this example is composed of a porous material and an ionic conductor liquid filled in the pores of the porous material, wherein the porous material is a semi-transparent polyvinylidene fluoride porous membrane, the ionic conductor liquid is an ionic liquid (1-ethyl-3-methylimidazolium hexafluorophosphate) , and the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: 10.
The performance test results of the sensor dielectric layer prepared in this example are shown in Table 1.
Comparison Example 1
The only difference from Example 1 is that, in this comparison example, no ionic conductor liquid was filled.
The performance test results of the sensor dielectric layer prepared in this comparison example are shown in Table 1.
Fig. 8 is a sensitivity test diagram of a pressure sensor fabricated from the dielectric layer provided by this comparison example. As can be seen from the figure, the maximum sensitivity of the device without being loaded with ionic conductor liquid is 0.245 KPa -1. As can be seen in conjunction with Figures 7, 8 and 4, the loading of the ionic active material allows great increase of both transparency and sensing ability of the device.
Comparison Example 2
The only difference from Example 1 is that, in this comparison example, the ionic conductor liquid was replaced by purified water.
The performance test results of the sensor dielectric layer prepared in this comparison example are shown in Table 1.
Comparison Example 3
The only difference from Example 1 is that, in the present comparison example, the polyvinylidene fluoride porous membrane was replaced by a glass.
The performance test results of the sensor dielectric layer prepared in this comparison example are shown in Table 1.
Test methods:
(1) The samples of the examples and comparison samples were tested using an ultraviolet-visible spectrophotometer, and the value of the transmissivity at 550 nm was selected as the transparency of the tested sample.
(2) Sensitivity test: the required pressure was applied to the samples through a press machine, and the change of the capacitance value of the sample was recorded using a multi-function tester, wherein the test frequency is set to 1×10 5 Hz, and the detection limit, response time and sensitivity of the tested sample were calculated through the relationship between the force and the change rate of the capacitance value.
(3) Flexibility test: both ends of the tested sample were held by hand and two opposite forces were applied to see if the sample can be twisted.
The test results are shown in the table below.
Table 1
Figure PCTCN2019094686-appb-000001
Figure PCTCN2019094686-appb-000002
In summary of the above examples and comparison examples, the sensor dielectric layers prepared in the examples of the present application have excellent optical transparency, and the sensor manufactured from the sensor dielectric layer has the advantages of low detection limit, fast response and high sensitivity. From the comparison between Example 1 and Comparison Examples 1-2, it can be seen that the dielectric layer loaded with the ionic conductor liquid prepared by the present application can not only effectively improve the transparency of the device, but also significantly improve the sensing performance. From the comparison between Example 1 and Comparison Examples 3, it can be seen that the use of a porous membrane as a substrate in the present application can better increase the sensing performance of the sensor.
The applicant declares that detailed features and detailed methods of the present application is illustrated by the above-described embodiments, but the present application is not limited to the above process steps, that is, it does not mean that the present application must be implemented in accordance with the process steps described above.

Claims (14)

  1. A sensor dielectric layer, wherein the dielectric layer comprises a porous material and an ionic conductor liquid filled in the pores of the porous material, and the porous material is a non-transparent or semi-transparent material.
  2. The sensor dielectric layer according to claim 1, wherein the mass ratio of the ionic conductor liquid to the porous material in the sensor dielectric layer is 1: (0.1-10) , optionally 1: (2-5) .
  3. The sensor dielectric layer according to claim 1 or 2, wherein the porous material has a porosity of 10%-99%, optionally 30-80%, optionally 60%.
  4. The sensor dielectric layer according to claim 1, wherein the porous material is a flexible material.
  5. The sensor dielectric layer according to any of claims 1-4, wherein the porous material comprises any one selected from the group consisting of a cloth, a paper, a plastic foam, a polyimide porous membrane, a polydimethylsiloxane porous membrane, a polyvinylidene fluoride porous membrane, a polystyrene porous membrane, a polylactic acid porous membrane, polypropylene porous membrane, a polyvinyl chloride porous membrane, a polyethylene porous membrane, a cellulose porous membrane, a cellulose acetate porous membrane and a nitrocellulose porous membrane, or a combination of at least two selected therefrom, optionally a polyvinylidene fluoride porous membrane.
  6. The sensor dielectric layer according to any of claims 1-5, wherein the porous material has a pore size of 0.01-100 μm, optionally 0.1-10 μm, optionally 5 μm.
  7. The sensor dielectric layer according to any of claims 1-6, wherein the porous material has a thickness of 0.01-100 mm, optionally 0.1-10 mm, optionally 0.5 mm.
  8. The sensor dielectric layer according to any of claims 1-7, wherein the ionic conductor liquid comprises any one selected from the group consisting of an ionic liquid, a sodium salt solution, a potassium salt solution, a sulphate solution, a nitrate solution, a chloride salt solution and a phosphate solution, or a combination of at least two selected therefrom; optionally, the ionic conductor liquid is an ionic liquid.
  9. A preparation method of the sensor dielectric layer according to any of claims 1-8, wherein the method comprises the following steps:
    mixing the ionic conductor liquid with the porous material, and allowing them to stand to obtain the sensor dielectric layer.
  10. The preparation method according to claim 9, wherein the means for mixing the ionic conductor liquid with the porous material comprises any one selected from the group consisting of suction filtration, titration, spray coating, coating and immersion, or a combination of at least two selected therefrom, optionally immersion.
  11. The preparation method according to claim 9 or 10, wherein the time for the standing is 1-120 min, optionally 10-60 min, optionally 30 min.
  12. The preparation method according to any of claim 9-11, wherein the preparation method further comprises:
    removing the excess ionic conductor liquid on the surface of the porous material after the standing;
    optionally, the means for removing the excess ionic conductor liquid on the surface of the porous material comprises any one selected from the group consisting of inversion standing, dust-free cloth wiping, glass rod roll wiping, oscillation and rotation, or a combination of at least two selected therefrom, optionally inversion standing.
  13. The preparation method according to any of claim 9-12, wherein the preparation method comprises the following steps:
    (1) mixing the ionic conductor liquid with the porous material by means of immersion, and allowing them to stand for 10-60 min;
    (2) removing the excess ionic conductor liquid on the surface of the porous material in the step (1)  by means of inversion standing to obtain the sensor dielectric layer.
  14. A use of the sensor dielectric layer according to any of claims 1-8, wherein the sensor dielectric layer is used in a flexible transparent sensor.
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CN106017748A (en) * 2016-05-19 2016-10-12 北京印刷学院 Capacitive flexible pressure sensor based on composite material dielectric layer and preparation method of capacitive flexible pressure sensor
CN106959176A (en) * 2017-05-10 2017-07-18 江西科技师范大学 A kind of pliable pressure sensor and preparation method thereof
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