阅读说明：本技术 一种基于pdms材料的包覆型压力传感器及其制备方法 (PDMS material-based coated pressure sensor and preparation method thereof ) 是由 张强 景柱 桑胜波 程永强 郝润芳 张虎林 袁仲云 冀健龙 禚凯 张文栋 于 2019-08-23 设计创作，主要内容包括：本发明一种基于PDMS材料的包覆型压力传感器及其制备方法,属于柔性压力传感器技术领域；所要解决的技术问题为：提供一种基于PDMS材料的包覆型压力传感器结构及其制备方法的改进；解决该技术问题采用的技术方案为：包括作为三维多孔框架的海绵复合骨架,所述海绵复合骨架的三维多孔结构表面包覆有PDMS材料,所述海绵复合骨架的内部还充填有导电纳米材料；所述海绵复合骨架的两侧分别设置有电极,所述电极通过PDMS薄膜键合在海绵复合骨架的表面；所述电极具体为表面涂覆有导电银浆的导电胶带；本发明应用于制作柔性触觉传感器。(The invention relates to a PDMS material-based coated pressure sensor and a preparation method thereof, belonging to the technical field of flexible pressure sensors; the technical problem to be solved is as follows: the coating type pressure sensor structure based on the PDMS material and the improvement of the preparation method thereof are provided; the technical scheme for solving the technical problem is as follows: the sponge composite framework is used as a three-dimensional porous framework, the surface of a three-dimensional porous structure of the sponge composite framework is coated with a PDMS material, and a conductive nano material is filled in the sponge composite framework; electrodes are respectively arranged on two sides of the sponge composite framework and bonded on the surface of the sponge composite framework through a PDMS film; the electrode is specifically a conductive adhesive tape with the surface coated with conductive silver paste; the invention is applied to manufacturing the flexible touch sensor.)

1. The utility model provides a cladding type pressure sensor based on PDMS material which characterized in that: the sponge composite structure comprises a sponge composite framework (1) serving as a three-dimensional porous framework, wherein a PDMS material (2) is coated on the surface of a three-dimensional porous structure of the sponge composite framework (1), and a conductive nano material (3) is filled in the sponge composite framework (1);

electrodes (4) are respectively arranged on two sides of the sponge composite framework (1), and the electrodes (4) are bonded on the surface of the sponge composite framework (1) through a PDMS (polydimethylsiloxane) film (5);

The electrode (4) is specifically a conductive adhesive tape with a conductive silver paste coated on the surface.

2. the PDMS material-based encapsulated pressure sensor of claim 1, wherein: the sponge composite framework (1) is characterized in that a PDMS material (2) is injected into the sponge through an injection pump, a dispenser or a 3D printer.

3. A PDMS material based encapsulated pressure sensor according to claim 2, characterized in that: the conductive nano material (3) is specifically graphene, a carbon nano tube or an MXene material.

4. a preparation method of a coating type pressure sensor based on PDMS material is characterized in that: the method comprises the following steps:

the method comprises the following steps: preparation of PDMS material (2):

Preparing a PDMS solution: placing the PDMS prepolymer and the curing agent in a mass ratio of 10:1 in a test tube, uniformly mixing, placing a part of the PDMS prepolymer and the curing agent in a culture dish to prepare a PDMS film (5), and placing the rest of PDMS in a refrigerator for later use;

preparation of PDMS film (5): putting the prepared PDMS into a culture dish, controlling the thickness to be about 1mm, and drying in a drying oven at the temperature of 70 ℃ for 1 h;

Step two: preparing a sponge composite skeleton (1) of a three-dimensional porous structure frame:

Washing the sponge with deionized water for 2-3 times, drying in a drying box, and cutting the dried sponge into the size of the required sensor;

sucking the prepared PDMS solution into an injector, injecting the PDMS solution into the pretreated sponge through the injector, wherein the volume of the injected PDMS solution is adapted to the size of the cut sponge block;

after injection is finished, extruding the sponge by different forces according to the requirement of preparing the sensing direction of the sensor, removing the extruded PDMS solution, taking out the sponge block, and slightly pressing to uniformly disperse the PDMS solution in the sponge block;

Step three: preparing a solution of the conductive nanomaterial (3):

Dispersing the required conductive nano material (3) in absolute ethyl alcohol, and performing ultrasonic treatment for 1h to obtain a suspension of the uniformly dispersed conductive nano material (3);

step four: preparing a flexible pressure sensor:

putting the sponge composite framework (1) coated by the PDMS solution into a suspension of the conductive nano material (3), and after the sponge sufficiently absorbs the suspension, putting the sponge into a drying box to dry for 4 hours at the temperature of 70 ℃;

Cutting the conductive adhesive tape into a size which is suitable for the sensor, coating conductive silver paste on the conductive adhesive tape, and adhering the dried sponge block and the conductive adhesive tape through the conductive silver paste to ensure that the conductive adhesive tape is adhered to the upper surface and the lower surface of the sponge block;

Cutting the prepared PDMS film (5) into a size which is suitable for the sensor, and sticking the PDMS film on the surface of the conductive adhesive tape;

and (3) putting the prepared sensor device into a drying box, drying for 3h at the temperature of 70 ℃, and taking out to finish the preparation.

Technical Field

The invention discloses a PDMS material-based coated pressure sensor and a preparation method thereof, and belongs to the technical field of flexible pressure sensors.

background

The electronic skin is one of the leading directions of research on intelligent materials and sensors, is also a new field for the development of the modern electronic information industry, and has important application value in the fields of artificial intelligence, communication entertainment, medical health and the like; the flexible touch sensor is an important component in electronic skin research, is an important way for a robot to sense external environment information only in vision, is one of necessary media for the robot to realize direct interaction with the external environment or a target, and has important scientific significance and application value for the future robot to explore the physical world.

With the development of scientific technology and the continuous improvement of production and preparation processes, higher requirements are put forward on the aspects of functional structures, appearance characteristics and the like of the robot touch sensor, and the flexible touch sensor with the characteristics of flexibility, wearing comfort, high sensitivity, high stability, large-area touch sensing and the like becomes a research hotspot of electronic skins; traditional silicon-based and metal strain gauge type touch sensors cannot meet functional requirements on flexibility, ductility, wearing comfort and the like, so that a force-sensitive conductive composite material prepared by filling a nano conductive material in a flexible substrate is widely applied to design of the flexible touch sensors.

according to different working principles, flexible touch sensors can be roughly divided into photoelectric type, piezoelectric type, resistance type, capacitance type and the like, wherein the capacitance type flexible touch sensor has the advantages of high sensitivity, high precision, high response speed, small delay, easiness in integration and the like, and is widely applied to the research of electronic skins of intelligent robots; the sensitivity of a traditional flexible touch sensor based on a composite material in a low-pressure area is low, in order to improve the sensing performance of the flexible touch sensor, a common method for improving the electronic skin touch detection sensitivity of a robot is to arrange a microstructure on a touch sensitive layer, the common microstructure mainly comprises a pyramid, a tentacle, a concave-convex shape, a microneedle structure and the like, a complex process flow such as photoetching, sputtering, evaporation, etching and the like is usually required in the preparation process of the microstructure when the microstructure is designed on the sensitive layer, and the defects that large-scale production is not easy to realize and the like exist.

The common preparation method of the three-dimensional porous microstructure composite conductive material comprises the following steps: vacuum freeze-drying and chemical vapor deposition; the principle of the vacuum freeze-drying method is that a wet material or solution is frozen into a solid state at a lower temperature (-50 ℃ to-10 ℃), then the moisture in the wet material or solution is directly sublimated into a gaseous state without a liquid state under vacuum (1.3 to 12Pa) so as to achieve the purpose of drying, and the flexible touch sensor prepared by the method can realize higher detection sensitivity (-0.8 kPa-1), lower detection lower limit (-0.24 Pa), quick response (-100 ms) and the like; but the vacuum freeze-drying method has the disadvantages of expensive equipment, energy consumption, high material preparation cost and the like;

Chemical Vapor Deposition (CVD) generally takes a three-dimensional foamed nickel material as a template, conductive materials such as graphene and the like are deposited on a three-dimensional framework in a chemical vapor mode, then the foamed nickel framework is removed through chemical etching, and graphene conductive foam with a three-dimensional porous microstructure can be obtained, and the flexible touch sensor prepared by the method can realize the touch sensing function of high sensitivity (strain coefficient GF is 35), quick response (about 30ms) and good stability (cycle number is more than 5000); however, chemical vapor deposition generally has the requirements of low deposition rate, easy pollution to the surface of the film and the environment in the deposition process, and corrosion resistance to equipment.

disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to solve the technical problems that: provides a coating type pressure sensor structure based on PDMS material and improvement of a preparation method thereof.

In order to solve the technical problems, the invention adopts the technical scheme that: a coating type pressure sensor based on PDMS materials comprises a sponge composite framework serving as a three-dimensional porous framework, wherein the surface of a three-dimensional porous structure of the sponge composite framework is coated with PDMS materials, and conductive nano materials are filled in the sponge composite framework;

electrodes are respectively arranged on two sides of the sponge composite framework and bonded on the surface of the sponge composite framework through a PDMS film;

the electrode is specifically a conductive adhesive tape with a conductive silver paste coated on the surface.

The sponge composite framework is characterized in that PDMS materials are injected into the sponge through an injection pump, a glue dispenser or a 3D printer.

the conductive nano material is specifically graphene, a carbon nano tube or an MXene material.

a preparation method of a PDMS material-based coated pressure sensor comprises the following steps:

The method comprises the following steps: preparing a PDMS material:

preparing a PDMS solution: placing the PDMS prepolymer and the curing agent in a test tube at a mass ratio of 10:1, uniformly mixing, placing a part of the PDMS prepolymer and the curing agent in a culture dish to prepare a PDMS film, and placing the rest of PDMS in a refrigerator for later use;

preparing a PDMS film: putting the prepared PDMS into a culture dish, controlling the thickness to be about 1mm, and drying in a drying oven at the temperature of 70 ℃ for 1 h;

Step two: preparing a sponge composite framework of a three-dimensional porous structure framework:

Washing the sponge with deionized water for 2-3 times, drying in a drying box, and cutting the dried sponge into the size of the required sensor;

Sucking the prepared PDMS solution into an injector, injecting the PDMS solution into the pretreated sponge through the injector, wherein the volume of the injected PDMS solution is adapted to the size of the cut sponge block;

After injection is finished, extruding the sponge by different forces according to the requirement of preparing the sensing direction of the sensor, removing the extruded PDMS solution, taking out the sponge block, and slightly pressing to uniformly disperse the PDMS solution in the sponge block;

step three: preparing a solution of the conductive nano material:

dispersing the required conductive nano material in absolute ethyl alcohol, and performing ultrasonic treatment for 1h to obtain a uniformly dispersed suspension of the conductive nano material;

Step four: preparing a flexible pressure sensor:

Putting the sponge composite framework coated by the PDMS solution into a suspension of a conductive nano material, and after the suspension is fully absorbed by the sponge, putting the sponge into a drying box to be dried for 4 hours at the temperature of 70 ℃;

cutting the conductive adhesive tape into a size which is suitable for the sensor, coating conductive silver paste on the conductive adhesive tape, and adhering the dried sponge block and the conductive adhesive tape through the conductive silver paste to ensure that the conductive adhesive tape is adhered to the upper surface and the lower surface of the sponge block;

Cutting the prepared PDMS film into a size which is suitable for the sensor, and sticking the PDMS film on the surface of the conductive adhesive tape;

And (3) putting the prepared sensor device into a drying box, drying for 3h at the temperature of 70 ℃, and taking out to finish the preparation.

Compared with the prior art, the invention has the following beneficial effects:

the three-dimensional porous flexible touch sensor provided by the invention takes a three-dimensional structure frame as a framework, and the conductive nano material is adhered by PDMS (polydimethylsiloxane), so that the detection range of the flexible pressure sensor can be controlled by controlling the content of PDMS, and meanwhile, the three-dimensional structure has good mechanical characteristics and can provide good stability and dynamic response;

The touch pressure sensor is prepared by adopting the sponge and the PDMS material in the form of adhering the conductive nano material, and has the advantages of low cost, simple process flow and benefit for macro preparation;

The invention takes commercially available sponge as a base material, and PDMS is combined with the conductive nano material, so that the price of the used material is low, and the requirements of electronic skin on flexibility, wearability and large-area touch perception can be well met;

compared with a vacuum freeze drying method and a chemical vapor deposition method, the sensor preparation method provided by the invention has the advantages that the three-dimensional porous microstructure composite conductive material is directly formed on the surface of the three-dimensional skeleton structure in a self-assembly mode of an impregnation wrapping method, the preparation cost is reduced, the process flow is simplified, the method is simple to prepare, the macro preparation is facilitated, and the like.

Drawings

The invention is further described below with reference to the accompanying drawings:

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic flow chart of the production process of the present invention;

FIG. 3 is a scanning electron microscope image of the pressure touch sensor;

FIG. 4 is a graph of sensitivity of a force down tactile sensor;

FIG. 5 is a graph of a cyclic test of a pressure touch sensor;

In the figure: 1 is a sponge composite framework, 2 is a PDMS material, 3 is a conductive nano material, 4 is an electrode and 5 is a PDMS film.

Detailed Description

as shown in fig. 1 and 2, the invention belongs to the field of flexible touch sensors, and particularly relates to a high-sensitivity flexible pressure sensor based on a PDMS coated three-dimensional structure and a preparation method thereof, which can be applied to touch sensing in the field of electronic skin.

in order to improve the mechanical property of the sensor, the three-dimensional skeleton of the sponge is used as a frame, the PDMS coats the three-dimensional porous structure, the conductive nano material is filled by utilizing the characteristics of the PDMS, and the conductive silver paste is adhered to the electrodes from top to bottom in the three-dimensional structure to form the flexible pressure sensor through self-assembly.

The three-dimensional porous pressure sensor is mainly obtained by taking sponge (but not limited to the sponge) as a three-dimensional porous frame, coating PDMS (polydimethylsiloxane) by using an injector, filling conductive nano materials (such as graphene, carbon nano tubes, MXene, conductive nano metal particles and the like) and impregnating the surface of the PDMS-coated three-dimensional porous structure with the conductive nano materials for self-assembly.

The PDMS is injected into the sponge through an injector (an injection pump, a dispenser, a 3D printer and the like), and is uniformly coated on the three-dimensional porous structure through extrusion with a certain force, so that redundant PDMS is removed.

And putting the PDMS-coated three-dimensional porous structure into the dispersion liquid of the conductive nano material for sufficient adsorption, and then putting the three-dimensional porous structure into a drying line for drying.

The electrodes are connected through the conductive silver paste and the conductive adhesive tape, and then the sensor is assembled through the PDMS film (also can be medical adhesive tape, SEBS thermoplastic rubber and the like).

The tactile pressure sensor provided by the invention is mainly obtained by taking sponge as a framework, adhering a conductive nano material by PDMS (polydimethylsiloxane), and self-assembling an adhesive electrode, and the preparation method comprises the following steps:

1. Preparing PDMS:

preparing a PDMS solution: placing the PDMS prepolymer and the curing agent in a test tube at a mass ratio of 10:1, uniformly mixing, placing a part of the PDMS prepolymer and the curing agent in a culture dish to prepare a PDMS film, and placing the rest of PDMS in a refrigerator for later use;

preparing a PDMS film: and (3) putting the prepared PDMS into a culture dish, controlling the thickness to be about 1mm, and drying in a drying oven at 70 ℃ for 1 h.

2. Three-dimensional porous structural framework:

washing commercially available melamine foaming sponge with deionized water for 2-3 times, drying in a drying oven, and cutting into 1 cubic centimeter blocks.

get its PDMS that will prepare of syringe and inhale 8ml in the syringe, take out the sponge that the preliminary treatment is good, stretch into the sponge with the syringe needle inside, inject PDMS into the sponge inside, press the sponge piece respectively through 800KPa, 500KPa, 250 KP's pressure, handle the PDMS that extrudes, take out the sponge piece and slightly press and make PDMS at sponge piece inside dispersion even.

3. Preparing a graphene solution:

and (3) putting 0.2mg of graphene into 20ml of absolute ethyl alcohol for dispersion, and carrying out ultrasonic treatment for 1h to obtain a uniformly dispersed graphene suspension.

4. preparing a three-dimensional porous flexible pressure sensor:

put into graphite alkene suspension after taking out PDMS coated sponge, put into drying oven 70 ℃ after fully absorbing and dry for 4h, take out after waiting to dry and tailor into 1cm wide rectangular with the electrically conductive adhesive tape, coat electrically conductive silver thick liquid on the electrically conductive adhesive tape and pass through the electrically conductive silver thick liquid adhesion with the electrically conductive adhesive tape sponge piece, the electrically conductive adhesive tape is located the upper and lower two-layer of sponge piece. Then cutting the prepared PDMS film into a square with the size of 1 cubic centimeter, and adhering the square to the upper layer and the lower layer of the conductive adhesive tape. And (3) putting the prepared device into a drying oven, drying for 3h at 70 ℃, and taking out, thus completing the preparation of the three-dimensional porous flexible touch sensor.

compared with a flexible pressure sensor without the PDMS coated sponge, the flexible pressure sensor with the PDMS coated sponge can effectively enable the conductive nano material to be adhered to the sponge, and the stability and consistency of the sensor are improved.

As shown in fig. 3, in particular to a scanning electron microscope image of the pressure touch sensor prepared by the present invention, it can be known from a Scanning Electron Microscope (SEM) image of Graphene @ PDMS @ MF sensor that: the distance between the cross-linked frameworks is about 60-80 mu m, the surface of the sponge framework is smooth under high magnification, the width of the framework is about 5-10 mu m, Graphene sheets in the Graphene @ PDMS @ MF sensor are uniformly dispersed on the sponge framework and stably adhered to the framework, and gaps between the frameworks are beneficial to improving the measurement range of the sensor.

as shown in fig. 4, specifically, a sensitivity comparison graph of the pressure tactile sensor prepared by the invention under different pressure values is shown, different measurement ranges and different sensitivities can be realized by extruding the sponge with different pressure values in the preparation method, and the corresponding measurement ranges and sensitivity sensors can be prepared according to requirements to realize application in different occasions.

as shown in fig. 5, particularly, the pressure tactile sensor cycle test chart prepared by the invention has a good resilience, and is of great significance for improving the dynamic characteristics of the pressure tactile sensor as a template of a three-dimensional porous microstructure composite medium layer, the flexible pressure tactile sensor obtained in the embodiment is cyclically loaded and unloaded in the chart, the stability and the repeatability of the flexible pressure tactile sensor are observed, and the test result is shown in the chart, and the flexible pressure tactile sensor prepared by the invention can still stably output after about 2000s loading and unloading experiments, so that the stability in the use process is ensured.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.