CN112595444A - Flexible displacement-pressure sensor - Google Patents
Flexible displacement-pressure sensor Download PDFInfo
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- CN112595444A CN112595444A CN202011344330.4A CN202011344330A CN112595444A CN 112595444 A CN112595444 A CN 112595444A CN 202011344330 A CN202011344330 A CN 202011344330A CN 112595444 A CN112595444 A CN 112595444A
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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
Abstract
The invention provides a flexible displacement-pressure sensor, which comprises an elastic displacement layer, a pressure sensitive layer and an electrode layer, wherein the elastic displacement layer is arranged on the elastic displacement layer; wherein, the surface of the elastic displacement layer is provided with a convex structure. The flexible displacement-pressure sensor provided by the embodiment of the invention has the characteristics of low cost, simple structure and the like.
Description
Technical Field
The invention relates to a displacement-pressure sensor, in particular to a flexible displacement-pressure sensor.
Background
In recent years, the development of flexible electronic technology is promoted by the wide application of intelligent wearable devices, and flexible sensors are widely researched as important components for acquiring information. The flexible sensor has the characteristics of thin structure, light weight, flexibility and the like, so that the flexible sensor has unique advantages in the application field. For example, in the field of human health, the flexible pressure sensor can be attached to the skin to monitor physiological activities of human body such as pulse, sound production, swallowing and the like, and is integrated into the sole to monitor gait; in the field of smart homes, the intelligent sleep monitoring system can be integrated into a mattress to monitor sleep; the airtightness of parts such as doors and windows can be tested in the production process of the automobile, and the pressure distribution of a wiper, an automobile seat, tires and the ground can be tested; the method can be used for testing the sealing performance of the screen edge in the mobile phone production industry and the like. The above applications represent the advantages of a thin film pressure sensor.
Along with the expansion of application scenes, a flexible sensor is required to monitor external force in a certain spatial range. For example, to monitor the pressure change of a force-applying object in real time, conventional thin film pressure sensors cannot detect the pressure change while the pressure change is large, which severely limits their application. Therefore, there is a need for a new flexible displacement-pressure sensor that solves or mitigates the above-mentioned problems.
A flexible displacement-pressure sensor is a sensor that can convert pressure and displacement changes into an electrical signal output. Compared with the traditional single-function sensor, the multifunctional flexible displacement-pressure sensor can sense the displacement change and the pressure, so that the multifunctional flexible displacement-pressure sensor can show wide application prospects in human-computer interface ends of intelligent equipment in various fields, such as emerging fields of intelligent bionic prostheses, rehabilitation medicine, intelligent robots, wearable equipment or flexible electronics.
Disclosure of Invention
It is a primary object of the present invention to provide a flexible displacement-pressure sensor, comprising an elastic displacement layer, a pressure sensitive layer and an electrode layer; wherein, the surface of the elastic displacement layer is provided with a convex structure.
The flexible displacement-pressure sensor provided by the embodiment of the invention has the characteristics of low cost, simple structure and the like.
Drawings
FIG. 1 is a schematic structural diagram of a flexible displacement-pressure sensor in accordance with an embodiment of the present invention;
FIG. 2a is a schematic structural diagram of an elastic displacement layer according to an embodiment of the present invention;
FIG. 2b is a schematic structural diagram of an elastically displacing layer according to another embodiment of the present invention;
FIG. 2c is a schematic structural diagram of an elastic displacement layer according to another embodiment of the present invention;
FIG. 2d is a schematic structural diagram of an elastic displacement layer according to another embodiment of the present invention;
FIG. 2e is a schematic structural diagram of an elastic displacement layer according to another embodiment of the present invention;
FIG. 2f is a schematic structural diagram of an elastic displacement layer according to another embodiment of the present invention;
FIG. 2g is a schematic diagram of a structure of an elastically displacing layer according to another embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an elastically displacing layer according to another embodiment of the present invention;
FIG. 4a is a graph showing a displacement performance test curve of the displacement-pressure sensor manufactured in example 1 of the present invention;
FIG. 4b is a pressure performance test curve of the displacement-pressure sensor made in example 1 of the present invention;
FIG. 5a is a graph showing a displacement performance test curve of the displacement-pressure sensor manufactured in example 2 of the present invention;
FIG. 5b is a pressure performance test curve of the displacement-pressure sensor made in example 2 of the present invention;
FIG. 6a is a graph showing a displacement performance test curve of the displacement-pressure sensor manufactured in example 3 of the present invention;
FIG. 6b is a pressure performance test graph of the displacement-pressure sensor manufactured in example 3 of the present invention;
FIG. 7a is a graph showing a displacement performance test curve of the displacement-pressure sensor manufactured in example 4 of the present invention;
FIG. 7b is a pressure performance test graph of the displacement-pressure sensor made in example 4 of the present invention;
FIG. 8a is a graph showing a displacement performance test curve of the displacement-pressure sensor manufactured in example 5 of the present invention;
FIG. 8b is a pressure performance test curve of the displacement-pressure sensor made in example 5 of the present invention.
Detailed Description
Exemplary embodiments that embody features and advantages of the invention are described in detail below in the specification. It is to be understood that the invention is capable of other embodiments and that various changes in form and details may be made therein without departing from the scope of the invention and the description and drawings are to be regarded as illustrative in nature and not as restrictive. Where "second" and the like are used to distinguish between a plurality of similarly named products, they are not intended to be limiting.
As shown in fig. 1, an embodiment of the present invention provides a flexible displacement-pressure sensor, including an elastic displacement layer 10, a pressure sensitive layer 20, and an electrode layer 30; wherein, a convex structure is arranged on the surface of the elastic displacement layer 10.
In one embodiment, the protruding structure comprises one or more of a cylinder, a cuboid, an at least partially spherical body, a pyramid, a cone, a truncated pyramid, a truncated cone, and an arch.
In one embodiment, at least a portion of the sphere comprises a sphere and/or a hemisphere, the hemisphere being cut from the sphere (the precursor) and having a rounded bottom surface with an arcuate top surface joining the bottom surface.
In one embodiment, the hemisphere may be 3/20-1/2 spheres, such as 1/2 sphere, 2/5 sphere, 1/5 sphere, etc.; wherein, 1/2 spheroid is equivalent to half of the parent body ball, and its height (the size from the top surface highest point to the bottom surface center) is 1/2 of the parent body ball diameter; 1/3 the height of the sphere is 1/3 of the diameter of the sphere of its parent body; and so on for others.
In one embodiment, the hemispheres may be disposed on the surface of the elastic displacement layer 10 through the circular bottom surface thereof.
In one embodiment, the cuboid may be disposed on a surface of the elastic displacement layer 10 through one surface thereof, and the cuboid may be, for example, a cube.
In one embodiment, the cylinder, pyramid, cone, frustum of pyramid, and circular truncated cone can be disposed on the surface of the elastic displacement layer 10 through their bottom surfaces.
In one embodiment, the pyramid may be a triangular pyramid, a rectangular pyramid, a pentagonal pyramid, a hexagonal pyramid, an octagonal pyramid, etc., and the pyramid may be connected to the surface of the elastic displacement layer 10 through the bottom surface thereof.
In one embodiment, the pyramid may be a regular pyramid, such as a regular triangular pyramid, a regular rectangular pyramid, a regular pentagonal pyramid, a regular hexagonal pyramid, a regular octagonal pyramid, and the like.
In one embodiment, the prism can be a triangular prism, a rectangular prism, a pentagonal prism, a hexagonal prism, an octagonal prism, etc., and the prism can be connected to the surface of the elastic displacement layer 10 through the bottom surface thereof.
In one embodiment, the prism table may be a regular prism table, such as a regular triangular prism table, a regular rectangular prism table, a regular five-sided prism table, a regular six-sided prism table, or a regular eight-sided prism table.
In one embodiment, the arch may be a portion of a cylinder, such as a structure obtained by cutting the cylinder along a plane parallel to the axis of the cylinder, such as an 1/2 cylinder, or a structure smaller than 1/2 cylinder, such as a 1/3 cylinder, a 1/4 cylinder, and the like.
In one embodiment, the protruding structure may be a cube as shown in fig. 2a, a hemisphere as shown in fig. 2b, an arch as shown in fig. 2c, a regular rectangular pyramid as shown in fig. 2d, a regular rectangular frustum as shown in fig. 2e, a cone as shown in fig. 2f, or a circular truncated cone as shown in fig. 2 g.
In one embodiment, the protrusion structure may be an array of a plurality of, for example, 4 cylinders as shown in fig. 3.
In one embodiment, the height of the protrusion structure may be 2-8 mm, such as 2mm, 5mm, 8mm, etc., wherein the height of the protrusion structure refers to the maximum dimension along the direction perpendicular to the elastic displacement layer 10.
In one embodiment, the length of the side or the diameter of the bottom of the protrusion structure may be 2-10 mm, such as 2mm, 6mm, 10mm, etc.
In one embodiment, the plurality of protruding structures are in a square array, and the plurality of protruding structures in the array are arranged at equal intervals; the convex structures are regular triangular pyramids or regular rectangular pyramids, the ratio of the side length of the bottom of each convex structure to the distance between two adjacent convex structures in the array is 1 (0.1-1.1), for example, the side length of each convex structure is 10mm, and the distance between two adjacent convex structures is 5 mm;
in one embodiment, the plurality of convex structures in the array are arranged in the same direction, for example, the convex structures are regular triangular pyramids, and the side length of the triangle at the base side of each convex structure is parallel to the corresponding side length of the triangle at the base side of the adjacent regular triangular pyramid.
In one embodiment, the protruding structures are regular pyramids, the number of sides n of a polygon at the bottom of the protruding structures is greater than or equal to 5, such as a regular pentagonal pyramid, a regular hexagonal pyramid or a regular octagonal pyramid, and the ratio of the maximum size of the bottom of the protruding structure to the distance between two adjacent protruding structures in the array is 1 (0.1-1.1). For example, the base of a regular hexagonal pyramid is a regular hexagon, the largest dimension of which is from one diagonal of the interior.
In one embodiment, the protruding structures are hemispheroids, and the ratio of the diameter of the bottom surface of each hemispheroid to the distance between two adjacent protruding structures in the array is 1 (0.1-1.1).
In one embodiment, the protruding structures are arch-shaped bodies obtained by cutting the cylinder along a plane parallel to the axis of the cylinder, the bottom of each arch-shaped body is square, and the ratio of the side length of each square to the distance between two adjacent protruding structures in the array is 1 (0.1-1.1).
The bottom or bottom surface of the convex structure refers to the part connected with the surface of the elastic displacement layer 10, and if the convex structure is a hemisphere, the hemisphere is connected with the elastic displacement layer 10 through a round bottom surface; if the convex structure is a regular triangular pyramid, the regular triangular pyramid is connected to the elastic displacement layer 10 through the bottom surface of the regular triangle. The pitch of the two raised structures refers to the shortest distance between the two raised structures on the elastomeric displacement layer 10.
In one embodiment, the protruding structure may be a solid structure.
In one embodiment, the material of the elastic displacement layer 10 may be rubber.
In one embodiment, the rubber used for the elastic displacement layer 10 may be one or more than two types of silicone rubber, such as ecoflex and/or Polydimethylsiloxane (PDMS).
In one embodiment, the pressure sensitive layer 20 is made of a conductive composition including an elastomer material, a carbon-based powder, and a conductive ink.
In one embodiment, the pressure sensitive layer 20 has force sensitive properties, for example, it can be a force sensitive conductive elastomer film, which can be a planar film or a surface microstructured film.
In one embodiment, the planar film is a film having two oppositely disposed planar surfaces.
In one embodiment, the planar film is prepared by coating the conductive composition slurry on a planar substrate and curing.
In one embodiment, the surface microstructured film is made by coating a slurry of the conductive composition onto a corresponding template substrate and curing.
In an embodiment, the surface microstructured film is formed by disposing at least one second protrusion structure on the surface of the planar film, where the second protrusion structure may be an irregular protrusion with gaussian distribution, or a plurality of independent second protrusion structures arranged in an array, where the second protrusion structure may be a cylinder, a cube, a hemisphere, a pyramid, a cone, a truncated pyramid, a circular truncated cone, or an arch.
In one embodiment, the elastic displacement layer 10 includes a first surface provided with a protruding structure and a second surface disposed opposite to the first surface, and the second surface may be a flat surface.
In one embodiment, the pressure sensitive layer 20 is disposed on the second surface of the elastic displacement layer 10, and the second protrusion structure is located on the surface of the pressure sensitive layer 20 away from the second surface.
In one embodiment, the elastomeric material may be rubber.
In one embodiment, the rubber may be silicone rubber, which may be ecoflex and/or Polydimethylsiloxane (PDMS).
In one embodiment, the carbon-based powder may be a powder based on carbon element, particularly a powder of a carbon simple substance, such as one or more of carbon fiber powder, biomass carbon, conductive carbon black, and graphite powder, and since the carbon-based powder is relatively low in price, the cost of the conductive elastomer film produced by using the carbon-based powder is reduced.
In one embodiment, the diameter of the carbon fiber powder may be 5 to 10 μm, such as 5 μm, 8 μm, 10 μm; the length may be 10 to 100 μm, for example, 20 μm, 30 μm, 50 μm, 80 μm, etc.
In one embodiment, the conductive ink may be a conductive carbon ink.
In one embodiment, the conductive composition includes 6 parts by mass of a carbon-based powder, 49 parts by mass of an elastomer material, and 31 parts by mass of a conductive ink.
As shown in fig. 1, the flexible displacement-pressure sensor according to an embodiment of the present invention includes a package layer 50, an elastic displacement layer 10, a pressure sensitive layer 20, a rubber ring 40, and an electrode layer 30, which are stacked.
In one embodiment, the electrode layer 30 includes a flexible substrate and a conductive trace formed on the flexible substrate; the flexible substrate may be, for example, polyethylene terephthalate (PET), Polyimide (PI), Polydimethylsiloxane (PDMS), or woven cloth; the conductive lines may be gold, silver or copper lines, for example.
In one embodiment, the electrode layer 30 may be an interdigitated electrode or a planar electrode.
In one embodiment, the pressure sensitive layer 20 is disposed between the elastic displacement layer 10 and the electrode layer 30.
The invention provides a preparation method of a flexible displacement-pressure sensor, which comprises the steps of sequentially laminating an elastic displacement layer 10, a pressure sensitive layer 20 and an electrode layer 30 (interdigital electrode), bonding and fixing by using a rubber ring, and packaging by using polyethylene terephthalate (PET).
In one embodiment, the method for assembling the elastic displacement layer 10 and the pressure sensitive layer 20 includes: after curing the elastomeric displacement layer 10, a slurry of the conductive composition is applied directly to the surface of the elastomeric displacement layer 10 without demolding.
In one embodiment, the method for assembling the elastic displacement layer 10 and the pressure sensitive layer 20 includes: coating the elastic displacement layer liquid on a substrate with patterns, putting the substrate coated with the liquid into a vacuum drying oven, vacuumizing at room temperature to remove bubbles, blade-coating a liquid film with a preset thickness by using a scraper, then putting the blade-coated substrate into a 70 ℃ blast drying oven for curing, taking out, cooling at room temperature, coating the conductive composition slurry on the surface of the elastic displacement layer 10, performing air suction curing, cooling at room temperature, and stripping to obtain the assembled elastic displacement layer-pressure sensitive layer.
In one embodiment, the patterned substrate may be a glass plate, a quartz plate, or a subgrid plate.
In one embodiment, the patterned substrate may be formed by engraving a predetermined pattern on the substrate with a laser.
In one embodiment, the method for assembling the elastic displacement layer 10 and the pressure sensitive layer 20 includes: after the elastic displacement layer liquid is coated on the substrate with the pattern, the pressure sensitive layer 20 film is flatly placed above the elastic displacement layer liquid; in particular, when the pressure sensitive layer 20 is a surface microstructured film, the planar layer of the surface microstructured film is placed flat against and above the elastic displacement layer liquid facing the elastic displacement layer liquid.
In one embodiment, the method for assembling the elastic displacement layer 10 and the pressure sensitive layer 20 includes: coating the elastic displacement layer liquid on a substrate with patterns, putting the substrate coated with the liquid into a vacuum drying box, vacuumizing at room temperature to remove air bubbles, blade-coating a liquid film with a preset thickness by using a scraper, and then flatly placing the pressure sensitive layer 20 film above the elastic displacement layer liquid; and then, putting the substrate subjected to blade coating into a 70 ℃ blast drying oven for curing, taking out, cooling at room temperature, and stripping to obtain the assembled elastic displacement layer-pressure sensitive layer.
The preparation method of the elastic displacement layer-pressure sensitive layer provided by the embodiment of the invention can effectively reduce the manufacturing cost and simplify the manufacturing steps.
In one embodiment, the flexible displacement-pressure sensor may include two planar electrodes, the pressure sensitive layer 20 is sandwiched between the two planar electrodes, the conductive traces of the two planar electrodes are disposed opposite to each other, and the elastic displacement layer 10 is disposed on the flexible substrate of the upper planar electrode.
In one embodiment, the assembly method of the elastic displacement layer 10 and the upper planar electrode may be as follows: after the elastic displacement layer liquid is coated on the substrate with the patterns, the flexible substrate layer of the planar electrode is flatly placed above the elastic displacement layer liquid and faces the elastic displacement layer liquid.
In one embodiment, the elastic displacement layer liquid is coated on a substrate with patterns, the substrate coated with the liquid is placed in a vacuum drying oven, vacuum pumping is carried out at room temperature to remove air bubbles, a liquid film with a preset thickness is blade-coated by a scraper, and then the flexible substrate layer of the planar electrode is flatly placed above the elastic displacement layer liquid facing the elastic displacement layer liquid; and then, putting the substrate subjected to blade coating into a 70 ℃ air-blast drying oven for curing, taking out, cooling at room temperature, and stripping to obtain the assembled elastic displacement layer-planar electrode.
According to the embodiment of the invention, the patterned displacement-pressure sensor can be prepared by utilizing the moldability of the elastomer material, so that the sensor has better current change in a displacement range of 0-3 mm, and can well detect the pressure while detecting the displacement. Has excellent sensing performance in practical potential application.
The flexible displacement-pressure sensor provided by the embodiment of the invention has a simple preparation process, can be used for preparing various patterns according to template design, and can also be used for preparing sensors with any shape and any size according to design, so that large-scale production is realized.
The displacement-pressure sensor provided by the embodiment of the invention is suitable for miniaturized and integrated equipment, and has wide application prospects in the fields of intelligent bionic artificial limbs, man-machine interaction, rehabilitation training and the like.
The flexible displacement-pressure sensor and the preparation thereof according to an embodiment of the present invention will be further described with reference to the accompanying drawings and specific examples. Wherein, the carbon fiber powder, the conductive carbon ink and the PDMS are all purchased from the market; the diameter range of the carbon fiber powder is 5-10 μm, and the length range is 10-100 μm. The related tests comprise a sensor displacement performance test and a pressure performance test, wherein a figure 5a shows the displacement performance test of the sensor, and the sensor has better linearity within the range of 0-3 mm. Fig. 5b is a pressure performance test of the sensor, the detection device is an MTS mechanical testing machine, and the performance condition of the sensor can be seen from the graph.
Example 1
Preparation of elastic displacement layer-pressure sensitive layer
Coating PDMS elastic displacement layer liquid on a substrate with cuboid protrusions (the bottom surface is square, the side length is 8mm, and the height is 6mm), putting the substrate coated with the liquid into a vacuum drying oven, vacuumizing at room temperature to remove bubbles, blade-coating a liquid film with a preset thickness by using a scraper, then putting the blade-coated substrate into a 70 ℃ blast drying oven for curing, taking out, and cooling at room temperature.
Adding carbon fiber powder with the diameter of 5 micrometers and the length of 20 micrometers into a PDMS main agent, uniformly dispersing through planets, then adding a curing agent, and uniformly stirring to obtain carbon fiber powder-PDMS composite slurry;
adding conductive carbon printing ink into the carbon fiber powder-PDMS composite slurry, and mechanically stirring uniformly to obtain conductive elastomer slurry; the mass fraction of the carbon fiber powder in the conductive elastomer slurry is 6%, and the mass fraction of the conductive carbon ink is 31%; coating the conductive elastomer slurry on the surface of the elastic displacement layer 10, removing bubbles in vacuum, coating with an adjustable scraper to a preset thickness, then placing in an air-blast drying oven for curing, and stripping to obtain the elastic displacement layer (with cuboid protrusions) -the pressure sensitive layer (a planar film).
Preparation of flexible displacement-pressure sensor
And (3) taking the PI interdigital electrode coated with copper on the surface as an electrode layer 30, and laminating the electrode layer with the elastic displacement layer-pressure sensitive layer to obtain the flexible displacement-pressure sensor.
FIG. 4a is a graph showing the displacement performance of the displacement-pressure sensor prepared in example 1, and the results show that the current increase in the range of 0-3 mm displacement maintains uniform linearity and goodness of fit R in the range of full range2Is 0.99. Figure 4b shows a pressure performance representation of the displacement-pressure sensor prepared in example 1. The results show that in the range of 0-10N, the current flow can be seenThe increase of (a) is in an overall rising state.
Example 2
Preparation of pressure-sensitive layer-planar electrode
Adding carbon fiber powder with the diameter of 5 micrometers and the length of 20 micrometers into a PDMS main agent, uniformly dispersing through planets, then adding a curing agent, and uniformly stirring to obtain carbon fiber powder-PDMS composite slurry;
adding conductive carbon printing ink into the carbon fiber powder-PDMS composite slurry, and mechanically stirring uniformly to obtain conductive elastomer slurry; the mass fraction of the carbon fiber powder in the conductive elastomer slurry is 6%, and the mass fraction of the conductive carbon ink is 31%; coating the conductive elastomer slurry on a glass plate, removing bubbles in vacuum, blade-coating a PET (polyethylene terephthalate) planar electrode conductive circuit with silver paste screen printed on the surface by using an adjustable scraper to a preset thickness, flatly placing the PET planar electrode conductive circuit facing the conductive elastomer slurry above the conductive elastomer slurry, then placing the PET planar electrode conductive circuit in an air-blast drying oven for curing and stripping to obtain a pressure sensitive layer (planar film) -planar electrode.
Preparation of elastic displacement layer-planar electrode-pressure sensitive layer
Coating ecoflex elastic displacement layer liquid on a substrate with a circular truncated cone protrusion (the circular diameter of the bottom surface is 10mm, the height is 5mm, and the circular diameter of the top surface is 6mm), putting the substrate coated with the liquid into a vacuum drying oven, vacuumizing at room temperature to remove air bubbles, scraping a liquid film with a preset thickness by using a scraper, and then flatly placing a pressure sensitive layer-planar electrode (a planar electrode flexible substrate layer faces the elastic displacement layer liquid) above the elastic displacement layer liquid facing the elastic displacement layer liquid. And then, putting the substrate subjected to blade coating into a 70 ℃ blast drying oven for curing, taking out, cooling at room temperature, and stripping to obtain the elastic displacement layer (with the circular truncated cone bulges), the planar electrode and the pressure sensitive layer (planar film).
Preparation of flexible displacement-pressure sensor
And (3) taking the PET planar electrode with the silver paste silk-screened surface as the other electrode layer 30, laminating the other electrode layer with the prepared elastic displacement layer, planar electrode and pressure sensitive layer together, and positioning the pressure sensitive layer 20 between the two planar electrodes to obtain the flexible displacement-pressure sensor.
Shown in FIG. 5aShown as the displacement performance display of the displacement-pressure sensor prepared in example 2, the results show that the current increase in the full-scale range maintains uniform linearity and goodness of fit R in the displacement range of 0-3 mm2Is 0.996. Figure 5b shows a pressure performance demonstration of the displacement-pressure sensor prepared in example 2. The results show that the current increases in the range of 0 to 10N, and the current also increases as a whole.
Example 3
Preparation of pressure-sensitive layer-planar electrode
Adding carbon fiber powder with the diameter of 5 micrometers and the length of 20 micrometers into a PDMS main agent, uniformly dispersing through planets, then adding a curing agent, and uniformly stirring to obtain carbon fiber powder-PDMS composite slurry;
adding conductive carbon printing ink into the carbon fiber powder-PDMS composite slurry, and mechanically stirring uniformly to obtain conductive elastomer slurry; the mass fraction of the carbon fiber powder in the conductive elastomer slurry is 6%, and the mass fraction of the conductive carbon ink is 31%; coating the conductive elastomer slurry on a glass plate, removing bubbles in vacuum, blade-coating a PET (polyethylene terephthalate) planar electrode conductive circuit with silver paste screen printed on the surface by using an adjustable scraper to a preset thickness, flatly placing the PET planar electrode conductive circuit facing the conductive elastomer slurry above the conductive elastomer slurry, then placing the PET planar electrode conductive circuit in an air-blast drying oven for curing and stripping to obtain a pressure sensitive layer (planar film) -planar electrode.
Preparation of elastic displacement layer-planar electrode-pressure sensitive layer
Coating ecoflex elastic displacement layer liquid on a substrate with four cylindrical protrusions (the bottom surface is 5mm in diameter, the height is 5mm, and the distance is 0.5mm), putting the substrate coated with the liquid into a vacuum drying oven, vacuumizing at room temperature to remove air bubbles, scraping a liquid film with a preset thickness by using a scraper, and then flatly placing a pressure sensitive layer-planar electrode (a planar electrode flexible substrate layer faces the elastic displacement layer liquid) above the elastic displacement layer liquid facing the elastic displacement layer liquid. And then, putting the substrate subjected to blade coating into a 70 ℃ forced air drying oven for curing, taking out, cooling at room temperature, and stripping to obtain the elastic displacement layer (with four cylindrical bulges), the planar electrode and the pressure sensitive layer (planar film).
Preparation of flexible displacement-pressure sensor
And (3) taking the PET planar electrode with the silver paste silk-screened surface as the other electrode layer 30, laminating the other electrode layer with the prepared elastic displacement layer, planar electrode and pressure sensitive layer together, and positioning the pressure sensitive layer 20 between the two planar electrodes to obtain the flexible displacement-pressure sensor.
FIG. 6a is a graph showing the displacement performance of the displacement-pressure sensor prepared in example 3, and the results show that the current increase in the range of 0-3 mm displacement maintains uniform linearity and goodness of fit R in the range of full range2Is 0.98. Figure 6b shows a pressure performance demonstration of the displacement-pressure sensor prepared in example 3. The results show that the current increases in the range of 0 to 10N, and the current also increases as a whole.
Example 4
Preparation of pressure-sensitive layers
Adding carbon fiber powder with the diameter of 5 micrometers and the length of 20 micrometers into a PDMS main agent, uniformly dispersing through planets, then adding a curing agent, and uniformly stirring to obtain carbon fiber powder-PDMS composite slurry;
adding conductive carbon printing ink into the carbon fiber powder-PDMS composite slurry, and mechanically stirring uniformly to obtain conductive elastomer slurry; the mass fraction of the carbon fiber powder in the conductive elastomer slurry is 6%, and the mass fraction of the conductive carbon ink is 31%; and coating the conductive elastomer slurry on a glass plate, removing bubbles in vacuum, coating with an adjustable scraper to a preset thickness, then placing in an air-blast drying oven for curing, and stripping to obtain the planar film.
Preparation of elastic displacement layer-pressure sensitive layer
Coating elastic displacement layer liquid with the mixing mass ratio of PDMS to ecoflex being 1:1 on a substrate with four regular rectangular pyramid bulges (the bottom surface is 5mm in side length, 5mm in height and 0.5mm in distance), putting the substrate coated with the liquid into a vacuum drying oven, vacuumizing at room temperature to remove air bubbles, blade-coating a liquid film with a preset thickness by using a scraper, and then flatly placing the prepared planar film above the elastic displacement layer liquid in a manner of facing the elastic displacement layer liquid; and then, putting the substrate subjected to blade coating into a 70 ℃ forced air drying oven for curing, taking out, cooling at room temperature, and peeling to obtain an elastic displacement layer (with 4 rectangular pyramid protrusions) -pressure sensitive layer (planar film) assembly.
Preparation of flexible displacement-pressure sensor
And (3) using the PET interdigital electrode with the surface screen printed with silver paste as an electrode layer 30, and superposing the electrode layer and the elastic displacement layer-pressure sensitive layer assembly together to obtain the flexible displacement-pressure sensor.
FIG. 7a is a graph showing the displacement performance of the displacement-pressure sensor prepared in example 4, and the results show that the current increase in the range of 0-3 mm displacement maintains uniform linearity and goodness of fit R in the range of full range2Is 0.994. Figure 7b shows a pressure performance demonstration of the displacement-pressure sensor prepared in example 4. The results show that the current increases in the range of 0 to 10N, and the current also increases as a whole.
Example 5
Preparation of pressure-sensitive layers
Adding carbon fiber powder with the diameter of 5 micrometers and the length of 20 micrometers into a PDMS main agent, uniformly dispersing through planets, then adding a curing agent, and uniformly stirring to obtain carbon fiber powder-PDMS composite slurry;
adding conductive carbon printing ink into the carbon fiber powder-PDMS composite slurry, and mechanically stirring uniformly to obtain conductive elastomer slurry; the mass fraction of the carbon fiber powder in the conductive elastomer slurry is 6%, and the mass fraction of the conductive carbon ink is 31%; and (3) coating the conductive elastomer slurry on a glass plate with a hemispheroid array, which is engraved by laser, and has the diameter of 0.2mm, the interval of 0.2mm and the depth of 50 mu m, removing bubbles in vacuum, scraping and coating the conductive elastomer slurry with a preset thickness by using an adjustable scraper, then placing the conductive elastomer slurry in an air-blast drying oven for curing at 100 ℃ for 2h, and stripping to obtain the surface microstructured conductive film with the hemispheroid array on one side surface.
Preparation of elastic displacement layer-pressure sensitive layer
The planar pressure sensitive layer film was replaced with a surface microstructured conductive film in the same procedure as in example 2. The planar layer of the surface microstructured conductive film faces the elastic displacement layer liquid. Obtaining the elastic displacement layer (with the circular truncated cone bulge) and the pressure sensitive layer (with the hemispherical bulge).
Preparation of flexible displacement-pressure sensor
And (3) using the PET interdigital electrode with the surface screen printed with silver paste as an electrode layer 30, and superposing the electrode layer with the elastic displacement layer-pressure sensitive layer combination, wherein the microstructure layer of the surface microstructured conductive film faces the interdigital electrode to obtain the flexible displacement-pressure sensor.
Fig. 8a shows the displacement performance of the displacement-pressure sensor prepared in example 5, and the result shows that the current keeps increasing continuously in the range of 0-3 mm displacement, and the increase of the current shows a nonlinear trend in the full-scale range. Figure 8b shows a pressure performance demonstration of the displacement-pressure sensor prepared in example 5. The results show that the increase in current is also in an overall rising state in the range of 0-10N. Compared with the embodiment 2, the linearity of the displacement-pressure sensor in the range of 0-3 mm is reduced by arranging the convex structure on the surface of the pressure sensitive layer.
Unless otherwise defined, all terms used herein have the meanings commonly understood by those skilled in the art.
The described embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the present invention, and those skilled in the art may make various other substitutions, alterations, and modifications within the scope of the present invention, and thus, the present invention is not limited to the above-described embodiments but only by the claims.
Claims (10)
1. A flexible displacement-pressure sensor comprises an elastic displacement layer, a pressure sensitive layer and an electrode layer; wherein, the surface of the elastic displacement layer is provided with a convex structure.
2. The flexible displacement-pressure sensor of claim 1, wherein the raised structure comprises one or more of a cylinder, a cuboid, an at least partially spherical body, a pyramid, a cone, a frustum, a truncated cone, an arch.
3. The flexible displacement-pressure sensor according to claim 2, wherein the cylinder, the pyramid, the cone, the frustum of a pyramid, or the frustum of a cone is disposed on a surface of the elastic displacement layer through respective bottom surfaces.
4. The flexible displacement-pressure sensor of claim 2, wherein the pyramid comprises one or more of a triangular pyramid, a rectangular pyramid, a pentagonal pyramid, a hexagonal pyramid, an octagonal pyramid; and/or the presence of a gas in the gas,
the prismatic table comprises one or more of a triangular prismatic table, a rectangular prismatic table, a five-prismatic table, a six-prismatic table and an eight-prismatic table; and/or;
the at least part of sphere comprises a sphere and/or a hemisphere, and the hemisphere is 3/20-1/2 sphere; and/or the presence of a gas in the gas,
the arch is a structure obtained by cutting the cylinder along a plane parallel to the axis of the cylinder.
5. The flexible displacement-pressure sensor of claim 4 wherein the raised structures are connected to the surface of the elastic displacement layer by a bottom surface; the bottom surface of the hemisphere is circular, and the bottom surface of the arch body is a cutting plane.
6. The flexible displacement-pressure sensor of claim 4, wherein the raised structures are one or more and a plurality of the raised structures are arranged in an array.
7. The flexible displacement-pressure sensor of claim 6, wherein the convex structures are regular triangular pyramids or regular rectangular pyramids, and the ratio of the side length of the bottom surface to the distance between two adjacent convex structures in the array is 1 (0.1-1.1); or
The convex structures are regular pyramids, the number n of the sides of a polygon on the bottom surface of the convex structures is more than or equal to 5, and the ratio of the maximum size of the polygon to the distance between two adjacent convex structures in the array is 1 (0.1-1.1);
the distance between the two convex structures refers to the shortest distance between the two convex structures on the elastic displacement layer.
8. The flexible displacement-pressure sensor of claim 6 wherein the raised structures are hemispheres having a ratio of bottom surface diameter to the pitch of two adjacent raised structures in the array of 1 (0.1-1.1); or
The convex structures are the arch-shaped bodies, the bottom surfaces of the convex structures are square cutting surfaces, and the ratio of the side length of each square to the distance between two adjacent convex structures in the array is 1 (0.1-1.1);
the distance between the two convex structures refers to the shortest distance between the two convex structures on the elastic displacement layer.
9. The flexible displacement-pressure sensor of claim 1 wherein the pressure sensitive layer comprises two oppositely disposed planar surfaces; or
The surface of the pressure sensitive layer is provided with at least one second protruding structure, the second protruding structure comprises one or more of a cylinder, a cube, a hemisphere, a pyramid, a cone, a frustum, a circular truncated cone and an arch, or the second protruding structure is in Gaussian distribution.
10. The flexible displacement-pressure sensor of claim 1, wherein the elastic displacement layer is made of rubber; the pressure sensitive layer is made of a conductive composition, and the conductive composition comprises an elastomer material, carbon-based powder and conductive ink.
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