CN109655180B - Flexible pressure sensor based on crack array structure and preparation method thereof - Google Patents
Flexible pressure sensor based on crack array structure and preparation method thereof Download PDFInfo
- Publication number
- CN109655180B CN109655180B CN201910041452.7A CN201910041452A CN109655180B CN 109655180 B CN109655180 B CN 109655180B CN 201910041452 A CN201910041452 A CN 201910041452A CN 109655180 B CN109655180 B CN 109655180B
- Authority
- CN
- China
- Prior art keywords
- flexible
- crack array
- flexible substrate
- crack
- conductive layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
- G01L1/2287—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges constructional details of the strain gauges
- G01L1/2293—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges constructional details of the strain gauges of the semi-conductor type
Abstract
The invention relates to a flexible pressure sensor based on a crack array structure and a preparation method thereof, wherein the flexible pressure sensor comprises the following components which are arranged from top to bottom in sequence: the flexible substrate comprises a flexible upper cover, an upper flexible substrate, an upper conducting layer, a lower flexible substrate and a flexible lower cover; one surface of the upper flexible substrate, which is opposite to the upper conductive layer, is provided with a crack array inverse structure; one surface of the lower flexible substrate, which is opposite to the lower conductive layer, is provided with a crack array structure; the upper conducting layer is provided with an upper electrode, and the lower conducting layer is provided with a lower electrode; the upper electrode and the lower electrode do not intersect. The flexible upper cover, the upper flexible substrate, the lower flexible substrate and the flexible lower cover are made of flexible materials. The flexible pressure sensor changes the characteristic of resistance by using the change of the contact area of the crack array structure on the surface of the flexible substrate and the inverse structure of the crack array under the action of external pressure, thereby improving the sensitivity and the reliability.
Description
Technical Field
The invention relates to a flexible pressure sensor technology, in particular to a flexible pressure sensor based on a crack array structure and a preparation method thereof.
Background
As an important component in the sensing layer of the Internet of things system, the sensor plays a crucial role in modern measurement, information interaction and automatic production processes. The sensor is a source of information acquisition and is a prerequisite component for determining system characteristics and performance indexes to a certain extent. With the progress of the modern technology and the rapid development of artificial intelligence, the depth and the breadth of people for collecting surrounding environment information are continuously improved, and the rigid sensor is difficult to meet the normal production and living requirements of human beings, so that the flexible pressure sensor is produced at the right moment.
The flexible pressure sensor is a flexible electronic device which converts force, such as pressure, tension, stress and the like, received by a sensitive body into an electrical signal, can be conformally attached to the surfaces of various irregular objects, can conveniently and accurately and quickly measure special environments and signals, has wide application prospects in the fields of human body sign detection (monitoring), intelligent man-machine interaction, intelligent robots, intelligent skin and the like, and is gradually paid attention to by people. According to the signal conversion mechanism, pressure sensors are mainly classified into resistive sensors, capacitive sensors, and piezoelectric sensors. Compared with other two types, the resistance type sensor has the advantages of simple device structure, stable detection resistance, higher sensitivity and the like. In order to keep consistent with the technical development trend that the object to be detected is complex in shape and the capability of capturing and processing information is increasingly enhanced, the actual working condition demands that various performance indexes, particularly the sensitivity and the stability, of the flexible pressure sensor are more and more strict. However, the conventional large-volume multifunctional sensor has difficulty in satisfying the above-described requirements. Therefore, the development of high-performance flexible pressure sensors is one of the important leading issues in the field of flexible electronics.
At present, a manufacturing method of a flexible pressure sensor mainly utilizes processing technologies such as ultraviolet lithography to prepare a substrate with a micro-nano structure, and a conductive active substance is covered on the substrate, so that the sensitivity and the reliability of the pressure sensor are improved. In the prior art, the main method of the flexible pressure sensor with the micro-nano structure is based on a regular pyramid-shaped, convex-bag-shaped and regular crack-shaped flexible pressure sensor. The working principle of the flexible pressure sensor based on the crack type is as follows: under the action of external weak load, the flexible substrate induces the contact area of the surface crack between the upper and lower flexible substrates to change, thereby causing resistance change. However, although these micro-nano structures give the sensor higher sensitivity and reliability, a series of processes such as corrosion, lithography, oxidation, nanoimprint, sputtering and the like involved in the template processing process have the disadvantages of high equipment dependence, high technical difficulty, high manufacturing cost and the like, and the practical application and popularization of the micro-nano structures are greatly limited. In addition, the lowest detected pressure limit is in need of further optimization. In addition, the resistance-type flexible pressure sensor developed based on the micro-nano scale crack structure realizes the generation of cracks in a mode of damaging the structure of the material, and the normal service life of the sensor is seriously influenced.
Therefore, it is necessary to provide a pressure sensor based on a surface regular crack structure and a low-cost, simple and controllable preparation method thereof, which can ensure the sensitivity and reliability of the pressure sensor and realize large-area commercial application.
Disclosure of Invention
Objects of the invention
The invention aims to overcome the defects of difficult processing and preparation, high technical requirement and the like of the conventional flexible pressure sensor, and provides the resistor-type flexible pressure sensor with the regular crack array structure and the preparation method thereof. Meanwhile, the obtained flexible pressure sensor is high in sensitivity and reliability, and has great potential in the aspects of human motion detection and vital sign monitoring.
(II) technical scheme
In order to achieve the purpose, the invention adopts the main technical scheme that:
a flexible pressure sensor based on a crack array structure comprises,
arranged from top to bottom in sequence: the flexible substrate comprises a flexible upper cover, an upper flexible substrate, an upper conducting layer, a lower flexible substrate and a flexible lower cover;
one surface of the upper flexible substrate, which is opposite to the upper conductive layer, is provided with a crack array structure;
one surface of the lower flexible substrate, which is opposite to the lower conductive layer, is provided with a crack array inverse structure;
the upper conducting layer is provided with an upper electrode, and the lower conducting layer is provided with a lower electrode; the upper electrode and the lower electrode do not intersect.
The flexible upper cover, the upper flexible substrate, the lower flexible substrate and the flexible lower cover are made of flexible materials;
the crack array structure comprises a groove;
the crack array inverse structure comprises a bump;
wherein, the crack array inverse structure of the upper flexible substrate is formed by manufacturing a template with a crack array structure;
the crack array structure of the lower flexible substrate is manufactured through a transition template, and the transition template is manufactured through the template with the crack array structure.
The depth of the grooves of the crack array structure is 1-2 mu m, and the average distance between the grooves is 2 mu m;
the height of the protrusions of the crack array inverse structure is 1-2 μm, and the average width between the protrusions is 2 μm.
The flexible material is one of polyamide, polydimethylsiloxane, polyimide or polyethylene terephthalate.
The upper conducting layer and the lower conducting layer are both made of silver nano metal particles.
On the other hand, the invention also provides a preparation method of the flexible pressure sensor, which comprises the following steps:
s1, preparing a template with a crack array structure;
s2, preparing an upper flexible substrate with a crack array reverse structure by using a template with a crack array structure;
s3, preparing a transition template with a crack array reverse structure by using the template with the crack array structure, and preparing a lower flexible substrate with the crack array structure by using the transition template with the crack array reverse structure;
s4, preparing an upper conductive layer on one side of the upper flexible substrate with the crack array reverse structure to obtain the upper flexible substrate with the upper conductive layer; preparing a lower conductive layer on one surface of the lower flexible substrate with the crack array structure to obtain a lower flexible substrate with the lower conductive layer;
s5, manufacturing a flexible upper cover on one surface, far away from the upper conductive layer, of the upper flexible substrate with the upper conductive layer to obtain a first flexible structure, and manufacturing a flexible lower cover on one surface, far away from the lower conductive layer, of the lower flexible substrate with the lower conductive layer to obtain a second flexible structure;
and S6, covering the first flexible structure on the second flexible structure, wherein the surface with the upper conductive layer in the first flexible structure is opposite to the surface with the lower conductive layer in the second flexible structure, so as to obtain the flexible pressure sensor.
The step S1 includes:
and (3) placing absolute ethyl alcohol into a culture dish with an upper cover, placing the culture dish and the upper cover on a heating table, and heating for a period of time to obtain the upper cover with the crack array structure, which is a template with the crack array structure.
The step S2 includes:
mixing the flexible material and the curing agent according to the mass ratio of 10:1, uniformly stirring, spin-coating on the surface of the crack array structure with the upper cover of the crack array structure, curing and stripping to obtain the flexible material film with the crack array reverse structure, which is an upper flexible substrate with the crack array reverse structure.
The step S3 includes:
mixing A, B groups in the epoxy AB glue according to the mass ratio of 3:1, uniformly stirring, spin-coating on the surface of the crack array structure with the upper cover of the crack array structure, curing and stripping to obtain an epoxy film with a crack array reverse structure, which is a transition template with the crack array reverse structure;
mixing the flexible material and the curing agent according to the mass ratio of 10:1, uniformly stirring, spin-coating on the surface of the crack array inverse structure of the transition template with the crack array inverse structure, curing and stripping to obtain the flexible material film with the crack array structure, which is a lower flexible substrate with the crack array structure.
The step S4 further includes:
the upper conducting layer is connected with the copper sheet electrode and the conducting wire and is an upper electrode;
the lower conducting layer is connected with the copper sheet electrode and the conducting wire and is a lower electrode;
wherein the upper electrode and the lower electrode do not intersect.
(III) advantageous effects
The invention has the beneficial effects that:
(1) compared with other resistance-type pressure sensors, the flexible pressure sensor provided by the invention has the advantages that the two flexible substrates respectively provided with the regular crack array structure and the crack array inverse structure are oppositely arranged, so that the contact area change of the crack array structure and the crack array inverse structure on the surface of the flexible substrate under the action of external pressure can be utilized to change the resistance characteristic, and the sensitivity and the reliability are improved.
(2) According to the invention, the crack array structure and the crack array inverse structure are generated on the surface of PDMS through film inversion and are integrally formed, so that the structure of the material is prevented from being damaged, and the service life of the sensor is prolonged.
(3) The flexible pressure sensor is simple in preparation method, and complex processes such as photoetching are not needed; in addition, the preparation cost is low, the preparation can be carried out in a large area, and the application prospect is wide.
Drawings
FIG. 1 is a schematic structural diagram of a flexible pressure sensor based on a crack array structure according to an embodiment of the present invention;
FIG. 2 is a surface topography of a template with a crack array structure prepared by a flexible pressure sensor according to an embodiment of the present invention;
FIG. 3 is an SEM image of an inverse structure of a flexible substrate surface crack array on a flexible pressure sensor according to an embodiment of the invention;
FIG. 4 is an SEM image of a surface crack array of a flexible substrate under a flexible pressure sensor according to an embodiment of the invention;
FIG. 5 is a schematic diagram of a method for manufacturing a flexible pressure sensor according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of an upper flexible substrate structure with a conductive layer on a flexible pressure sensor strip according to an embodiment of the present invention;
FIG. 7 is a schematic view of a lower flexible substrate with a lower conductive layer of a flexible pressure sensor strip according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of an electrode structure of a flexible pressure sensor according to an embodiment of the present invention;
FIG. 9 is a schematic view of a structure of a lower electrode of a flexible pressure sensor according to an embodiment of the present invention;
FIG. 10 is a schematic view of a first compliant structure according to an embodiment of the present invention;
FIG. 11 is a schematic view of a second compliant structure according to an embodiment of the present invention;
FIG. 12 is a schematic structural diagram of a flexible pressure sensor in accordance with an embodiment of the present invention;
FIG. 13 is a graph of sensitivity versus pressure for a flexible pressure sensor in accordance with an embodiment of the present invention;
FIG. 14 is a graph showing the sensitivity change of a flexible pressure sensor prepared according to the present invention in a cyclic loading state;
FIG. 15 is a graph of response time and recovery time for a flexible pressure sensor made in accordance with the present invention;
FIG. 16 is a graph of response time and recovery time for a flexible pressure sensor made in accordance with the present invention;
fig. 17 is a graph of the low detection limit of a flexible pressure sensor made in accordance with the present invention.
Detailed Description
For a better understanding of the present invention, reference will now be made in detail to the present invention by way of specific embodiments thereof.
As shown in fig. 1, an embodiment of the present invention provides a flexible pressure sensor based on a crack array structure, which includes, sequentially arranged from top to bottom: flexible upper cover 1, upper flexible substrate 2, upper conductive layer 3, lower conductive layer 4, lower flexible substrate 5, and flexible lower cover 6
The flexible upper cover 1 and the flexible lower cover 6 are disposed in parallel with each other for protecting the upper flexible substrate 2 and the lower flexible substrate 5. The lower surface of the flexible upper cover 1 is conformally covered on the upper surface of the upper flexible substrate 2, and the lower surface of the lower flexible substrate 5 is conformally covered on the flexible lower cover 6.
The upper conductive layer 3 is sputter coated on the lower surface of the upper flexible substrate 2 and the lower conductive layer 4 is sputter coated on the upper surface of the lower flexible substrate 5.
An upper electrode 7 is provided on the upper conductive layer, and the upper electrode 7 includes a copper electrode and a lead-out copper wire.
The lower conducting layer is provided with a lower electrode 8, and the lower electrode 8 comprises a copper electrode and a lead-out copper wire.
The upper conductive layer 3 and the lower conductive layer 4 naturally contact each other, but the upper electrode 7 and the lower electrode 8 do not contact and do not intersect. Preferably, the upper electrode 7 is located at one end of the flexible pressure sensor and the lower electrode 8 is located at the other end of the flexible pressure sensor, so that the upper conductive layer 3 and the lower conductive layer 4 contact each other to maximize the effective working area.
The surface of the upper flexible substrate 2 opposite to the upper conductive layer 3, namely the lower surface of the upper flexible substrate 2 is provided with a crack array inverse structure;
the side of the lower flexible substrate 5 opposite to the lower conductive layer 4, i.e., the upper surface of the lower flexible substrate 5, has a crack array structure.
Specifically, the crack array pattern is shown in fig. 2. In this example, regular cracks of relatively high parallelism in the crack array pattern were selected. The crack array structure includes grooves as shown in fig. 4, and the crack array inverse structure includes protrusions as shown in fig. 3. When the upper flexible substrate 2 and the lower flexible substrate 5 are mated with each other, the protrusions of the crack array inverse structure are located in the grooves of the crack array structure.
Preferably, the depth of the grooves of the crack array structure is 1-2 μm, and the average distance between the grooves is 2 μm;
the height of the protrusions of the crack array inverse structure is 1-2 μm, and the average width between the protrusions is 2 μm.
The flexible upper cover 1, the upper flexible substrate 2, the lower flexible substrate 5 and the flexible lower cover 6 in the flexible pressure sensor are all made of flexible materials.
The flexible material is one of Polyamide (PA), Polydimethylsiloxane (PDMS), Polyimide (PI) or polyethylene terephthalate (PET).
In order to prevent allergy and inflammation after the flexible pressure sensor is contacted with the skin, the flexible upper cover and the flexible lower cover of the embodiment of the invention both adopt polyethylene terephthalate (PET) films, and the thickness of the PET films is 50 μm.
Further, the upper flexible substrate and the lower flexible substrate are both made of cured Polydimethylsiloxane (PDMS).
In order to provide the flexible pressure sensor with excellent flexibility and stability, the thicknesses of the flexible upper cover and the flexible lower cover are the same, and are preferably 300 μm.
Preferably, the upper conductive layer and the lower conductive layer are made of silver (Ag) nano metal particles. The thickness was 50 nm.
On the other hand, as shown in fig. 5, the present embodiment provides a method for manufacturing a flexible pressure sensor, specifically, the method includes the steps of:
and S1, preparing a template with a crack array structure.
This example utilizes the characteristic of polystyrene being susceptible to stress cracking, and selects Polystyrene (PS) petri dishes with lids for bacterial isolation, commonly used in biological laboratories, as precursors for the preparation of crack arrays: the selected PS culture dish is a qualified sample with three small white cards, no grid division and roundness, no scratch on the surface and no stain.
Specifically, step S1 includes:
and (3) placing absolute ethyl alcohol into a culture dish with an upper cover, placing the culture dish and the upper cover on a heating table, and heating for a period of time to obtain the upper cover with the crack array structure, which is a template with the crack array structure.
S11, injecting absolute ethyl alcohol into the culture dish with the upper cover.
In the experimental process, 100% absolute ethyl alcohol, ɸ 90mm Polystyrene (PS) culture dishes with covers and an accurate temperature control heating table are used.
And S12, covering the culture dish filled with the absolute ethyl alcohol with an upper cover, and placing the culture dish on a heating table for heating for a period of time.
And (3) injecting absolute ethyl alcohol into the PS culture dish, covering the PS culture dish with a cover, and placing the PS culture dish on a heating table for heating, wherein the heating temperature does not exceed the glass transition temperature of the PS culture dish.
The heating stage temperature was set to 81 ℃, the room temperature was kept constant at 21 ℃, and the temperature was raised to a preset value. Adding 4ml of absolute ethanol solution into the PS culture dish, covering the PS culture dish, placing the PS culture dish on a heating table for heating, starting timing, and heating for a preset time period.
In this example, the heating time was 8 hours.
S13, the culture dish is taken down from the heating table, and the upper cover with the crack array structure is obtained.
After heating for a certain time, the culture dish is taken down from the heating platform, a linear regular crack array appears on the inner surface of the upper cover of the PS culture dish, the array is in radial distribution as a whole, but cracks which are parallel to each other appear in a small area. As shown in fig. 2.
The principle that regular cracks are generated on the inner surface of the upper cover of the culture dish is as follows: the main chain of the PS is a saturated carbon chain, and the side group is a conjugated benzene ring, so that the molecular structure is irregular, the rigidity of the molecule is increased, and the PS becomes an amorphous linear polymer. Stress cracking is easily caused due to the rigidity of the molecular chain. This stress cracking property of PS makes it a template for the preparation of regular ordered crack arrays. Absolute ethyl alcohol is selected as an organic inducing solvent, and a solvent inducing method is used for preparing a regular crack array on the inner surface of the upper cover of the PS culture dish with the cover. When a PS culture dish with a cover and a certain volume of absolute ethyl alcohol is heated, the liquid absolute ethyl alcohol is heated and evaporated into ethanol steam, and when the ethanol steam contacts the inner surface of the upper cover of the culture dish, the ethanol steam is condensed into a layer of liquid film on the inner surface of the upper cover of the culture dish due to the temperature gradient (the heating temperature is greater than the indoor temperature) existing on the inner surface and the outer surface of the upper cover of the culture dish. The ethanol molecules are heated and move to be aggravated, and then permeate into the PS molecular grids to form an expansion layer below the inner surface of the upper cover of the PS culture dish. When the liquid absolute ethyl alcohol is completely evaporated, the absorbed ethyl alcohol is heated and released from the expansion layer. At this time, the inner surface of the upper cover of the PS culture dish shrinks, and the tension of the inner surface of the upper cover is generated and gradually increased. Cracks will develop at the inner surface when surface tension overcomes the weaker van der waals forces between the molecular chains. The uniaxial PS molecular chain distribution will make the crack propagate in a straight line on the surface. When the absorbed ethanol is completely released, the expansion layer stops shrinking and the crack stops growing. Thus, a regular linear crack array is obtained on the inner surface of the PS upper cover. However, as the PS culture dish is manufactured by injection molding, three small white cards are arranged at the edge of the upper cover of the PS culture dish and are distributed at 120 degrees. The presence of a small white card concentrates the stress therein, more likely to induce cracks in the white card. Thus, a radial array of linear cracks was present on the inner surface of the upper lid of the PS dish.
S2, preparing an upper flexible substrate with a crack array reverse structure by using the template with the crack array structure.
In this embodiment, the upper flexible substrate is made of Polydimethylsiloxane (PDMS), and the PDMS is spin-coated on the inner surface of the upper cover of the PS culture dish to obtain a PDMS film with a regular crack array inverse structure on the surface as the upper flexible substrate. Specifically, the method comprises the following steps:
mixing the flexible material and the curing agent according to the mass ratio of 10:1, uniformly stirring, spin-coating on the surface of the crack array structure with the upper cover of the crack array structure, curing and stripping to obtain the flexible material film with the crack array reverse structure, which is an upper flexible substrate with the crack array reverse structure.
And S21, mixing the flexible material and the curing agent according to the mass ratio of 10:1, uniformly stirring, spin-coating on the surface of the crack array structure with the crack array structure upper cover, and curing and stripping to obtain the flexible material film with the crack array reverse structure.
Uniformly mixing the prepolymer of the organic silicon PDMS and the curing agent according to the weight ratio of 10:1, and spin-coating the mixed solution on the inner surface of the upper cover of the PS culture dish at a low speed by a spin-coating machine.
And S22, curing the upper cover with the crack array structure coated with the flexible material in a spinning mode.
And degassing the upper cover with the crack array structure, which is coated with the flexible material in a spinning mode, for 1 hour by using a vacuum pump, heating the upper cover in an oven at 70 ℃ for 2 hours, and taking out the upper cover.
And S23, stripping the flexible material film with the crack array reverse structure from the solidified upper cover with the crack array reverse structure and coated with the flexible material in a spinning mode.
Stripping the cured PDMS film from the upper cover of the PS culture dish to obtain an upper flexible substrate with a regular crack array reverse structure; in this embodiment, the thickness of the upper flexible substrate is about 300 μm, and the height and width of the anti-structural unit of the surface crack array are both in the micrometer scale. An SEM image of the crack array on the surface of the upper flexible substrate is shown in FIG. 3.
S3, preparing a transition template with a crack array inverse structure by using the template with the crack array structure, and preparing a lower flexible substrate with the crack array structure by using the transition template with the crack array inverse structure.
And selecting epoxy AB glue as an intermediate transition template, and spin-coating the epoxy AB glue on the inner surface of the upper cover of the PS culture dish to prepare the film with the crack array reverse structure on the surface. And spin-coating PDMS on the intermediate transition template prepared in S5 to obtain a PDMS film with a regular array of cracks on the surface as a lower flexible substrate. Specifically, the method comprises the following steps:
s31, mixing A, B groups in the epoxy AB adhesive according to the mass ratio of 3:1, uniformly stirring, spin-coating on the surface of the crack array structure with the upper cover of the crack array structure, curing and stripping to obtain the epoxy film with the crack array reverse structure, which is a transition template with the crack array reverse structure.
Accurately weighing A, B groups in the epoxy AB glue according to the mass ratio of 3:1, mixing the two components, fully and uniformly stirring, spin-coating the mixed solution on the surface of the upper cover of the PS culture dish with the crack array structure at a low speed by a spin coating machine, degassing for 10 minutes by a vacuum pump, heating for two hours at 70 ℃ in an oven, taking out, and stripping the cured epoxy AB glue from the upper cover of the PS culture dish to obtain the epoxy film template with the crack array reverse structure.
S32, mixing the flexible material and the curing agent according to the mass ratio of 10:1, uniformly stirring, spin-coating on the surface of the crack array inverse structure of the transition template with the crack array inverse structure, curing and stripping to obtain the flexible material film with the crack array structure, which is the lower flexible substrate with the crack array structure.
Uniformly mixing the prepolymer of the organic silicon PDMS and a curing agent according to the weight ratio of 10:1, spin-coating the mixed solution on a transition template with a crack array reverse structure at a low speed by a spin coating machine, degassing for 1 hour by a vacuum pump, heating in an oven at 70 ℃ for 2 hours, and taking out;
stripping the cured PDMS film from the epoxy resin template coated with PDMS in a spinning mode to obtain a lower flexible substrate with a regular crack array; in this embodiment, the thickness of the lower flexible substrate is about 300 μm, and both the height and the width of the surface crack array structure unit are in the micrometer scale. SEM image of the surface crack array structure of the lower flexible substrate is shown in FIG. 4
Optionally, before performing step S4, it is also possible to:
and (3) performing Scanning Electron Microscope (SEM) representation on the surface of the prepared upper flexible substrate and the lower flexible substrate to obtain the surface micro-morphology, wherein the representation results are shown in fig. 3 and 4.
Selecting a region with better parallelism of crack patterns in the crack array inverse structure of the upper flexible substrate
And selecting an area with better parallelism of crack patterns in the lower flexible substrate crack array structure.
The upper flexible substrate is placed under a metallographic microscope to observe the appearance of cracks, an area with better parallelism in the crack array inverse structure is selected for cutting, the length of the area is × mm, the width of the area is l × w, the size of the area is 40mm × 10mm,
the lower flexible substrate is placed under a metallographic microscope to observe the appearance of the cracks, the region with better parallelism in the crack array structure is selected for cutting, the length (l × w) of the size is × mm, the width (l × w) of the size is 40mm, the width of the size is × 10mm,
s4, preparing an upper conductive layer on one side of the upper flexible substrate with the crack array reverse structure to obtain the upper flexible substrate with the upper conductive layer; and preparing a lower conductive layer on one side of the lower flexible substrate with the crack array structure to obtain the lower flexible substrate with the lower conductive layer.
And sputtering and coating a silver nano metal particle conducting layer with the thickness of 50nm on the surface of the lower flexible substrate and the surface of the upper flexible substrate after surface treatment.
Performing surface treatment on PDMS for 20s by using the power of an ION40 plasma system (plasma) of 120W and the airflow of 150SSCM to enhance the adhesion of metal Ag to the PDMS; the resulting upper flexible substrate with the upper conductive layer is shown in fig. 6, and the lower flexible substrate with the lower conductive layer is shown in fig. 7.
A silver nano metal particle conducting layer with the thickness of 50nm is coated on the surface of the lower flexible substrate with a radial regular crack array structure and the surface of the upper flexible substrate with a regular crack array reverse structure in a sputtering way;
connecting the copper sheet electrode and the conductive wire to the upper conductive layer to form an upper electrode, as shown in fig. 8;
connecting the copper sheet electrode and the conductive wire on the lower conductive layer to form a lower electrode, as shown in fig. 9;
wherein the upper electrode and the lower electrode do not intersect.
S5, manufacturing a flexible upper cover on the surface, far away from the upper conductive layer, of the upper flexible substrate with the upper conductive layer to obtain a first flexible structure, and manufacturing a flexible lower cover on the surface, far away from the lower conductive layer, of the lower flexible substrate with the lower conductive layer to obtain a second flexible structure.
Attaching a layer of PET film with the thickness of 50 μm on the upper surface of the upper flexible substrate and the upper surface of the lower flexible substrate, and making flexible upper and lower covers; the first flexible structure is shown in fig. 10 and the second flexible structure is shown in fig. 11.
And S6, covering the first flexible structure on the second flexible structure, wherein the surface with the upper conductive layer in the first flexible structure is opposite to the surface with the lower conductive layer in the second flexible structure, so as to obtain the flexible pressure sensor.
The upper flexible substrate and the lower flexible substrate are placed face to form a flexible pressure sensor as shown in fig. 12, and a measurement circuit is connected to measure performance parameters.
The flexible pressure sensor based on the crack array structure has high sensitivity and high stability, and is shown in fig. 13 and 14. The flexible pressure sensor has the sensitivity of 27kPa-1 in the pressure range of less than 2.4kPa, and the resistance change is stable after multiple cyclic loading. At the same time, the flexible pressure sensor of the present invention possesses lower pressure detection, as shown in fig. 17. In addition, as shown in fig. 15 and 16, the flexible pressure sensor of the present invention has faster response time and recovery time.
It is to be understood that the invention is not limited to the specific arrangements and instrumentality described above and shown in the drawings. A detailed description of known methods is omitted herein for the sake of brevity. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present invention are not limited to the specific steps described and illustrated, and those skilled in the art can make various changes, modifications and additions or change the order between the steps after comprehending the spirit of the present invention.
Finally, it should be noted that: the above-mentioned embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill 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.
Claims (9)
1. A flexible pressure sensor based on a crack array structure is characterized by comprising,
arranged from top to bottom in sequence: the flexible substrate comprises a flexible upper cover, an upper flexible substrate, an upper conducting layer, a lower flexible substrate and a flexible lower cover;
one surface of the upper flexible substrate, which is opposite to the upper conductive layer, is provided with a crack array inverse structure;
one surface of the lower flexible substrate, which is opposite to the lower conductive layer, is provided with a crack array structure;
the upper conducting layer is provided with an upper electrode, and the lower conducting layer is provided with a lower electrode; the upper electrode and the lower electrode do not intersect;
the flexible upper cover, the upper flexible substrate, the lower flexible substrate and the flexible lower cover are made of flexible materials;
the crack array structure comprises a groove;
the crack array inverse structure comprises a bump;
when the upper flexible substrate and the lower flexible substrate are matched with each other, the projection of the crack array reverse structure is positioned in the groove of the crack array structure;
wherein, the crack array inverse structure of the upper flexible substrate is formed by manufacturing a template with a crack array structure;
the crack array structure of the lower flexible substrate is manufactured through a transition template, and the transition template is manufactured through the template with the crack array structure.
2. The flexible pressure sensor of claim 1,
the depth of the grooves of the crack array structure is 1-2 mu m, and the average distance between the grooves is 2 mu m;
the height of the protrusions of the crack array inverse structure is 1-2 μm, and the average width between the protrusions is 2 μm.
3. The flexible pressure sensor of claim 1,
the flexible material is one of polyamide, polydimethylsiloxane, polyimide or polyethylene terephthalate.
4. The flexible pressure sensor of claim 1,
the upper conducting layer and the lower conducting layer are both made of silver nano metal particles.
5. A method of manufacturing a flexible pressure sensor according to any of claims 1 to 4, comprising the steps of:
s1, preparing a template with a crack array structure;
s2, preparing an upper flexible substrate with a crack array reverse structure by using a template with a crack array structure;
s3, preparing a transition template with a crack array reverse structure by using the template with the crack array structure, and preparing a lower flexible substrate with the crack array structure by using the transition template with the crack array reverse structure;
s4, preparing an upper conductive layer on one side of the upper flexible substrate with the crack array reverse structure to obtain the upper flexible substrate with the upper conductive layer; preparing a lower conductive layer on one surface of the lower flexible substrate with the crack array structure to obtain a lower flexible substrate with the lower conductive layer;
s5, manufacturing a flexible upper cover on one surface, far away from the upper conductive layer, of the upper flexible substrate with the upper conductive layer to obtain a first flexible structure, and manufacturing a flexible lower cover on one surface, far away from the lower conductive layer, of the lower flexible substrate with the lower conductive layer to obtain a second flexible structure;
and S6, covering the first flexible structure on the second flexible structure, wherein the surface with the upper conductive layer in the first flexible structure is opposite to the surface with the lower conductive layer in the second flexible structure, so as to obtain the flexible pressure sensor.
6. The method according to claim 5, wherein the step S1 includes:
and (3) placing absolute ethyl alcohol into a culture dish with an upper cover, placing the culture dish and the upper cover on a heating table, and heating for a period of time to obtain the upper cover with the crack array structure, which is a template with the crack array structure.
7. The method according to claim 6, wherein the step S2 includes:
mixing the flexible material and the curing agent according to the mass ratio of 10:1, uniformly stirring, spin-coating on the surface of the crack array structure with the upper cover of the crack array structure, curing and stripping to obtain the flexible material film with the crack array reverse structure, which is an upper flexible substrate with the crack array reverse structure.
8. The method according to claim 6, wherein the step S3 includes:
mixing A, B groups in the epoxy AB glue according to the mass ratio of 3:1, uniformly stirring, spin-coating on the surface of the crack array structure with the upper cover of the crack array structure, curing and stripping to obtain an epoxy film with a crack array reverse structure, which is a transition template with the crack array reverse structure;
mixing the flexible material and the curing agent according to the mass ratio of 10:1, uniformly stirring, spin-coating on the surface of the crack array inverse structure of the transition template with the crack array inverse structure, curing and stripping to obtain the flexible material film with the crack array structure, which is a lower flexible substrate with the crack array structure.
9. The method according to claim 6, wherein the step S4 further comprises:
the upper conducting layer is connected with the copper sheet electrode and the conducting wire and is an upper electrode;
the lower conducting layer is connected with the copper sheet electrode and the conducting wire and is a lower electrode;
wherein the upper electrode and the lower electrode do not intersect.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910041452.7A CN109655180B (en) | 2019-01-16 | 2019-01-16 | Flexible pressure sensor based on crack array structure and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910041452.7A CN109655180B (en) | 2019-01-16 | 2019-01-16 | Flexible pressure sensor based on crack array structure and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109655180A CN109655180A (en) | 2019-04-19 |
| CN109655180B true CN109655180B (en) | 2020-07-21 |
Family
ID=66118938
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910041452.7A Active CN109655180B (en) | 2019-01-16 | 2019-01-16 | Flexible pressure sensor based on crack array structure and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109655180B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110031135B (en) * | 2019-05-20 | 2021-07-09 | 中国科学院重庆绿色智能技术研究院 | Tactile/tactile sensor, method for manufacturing tactile/tactile sensor, electronic device, braille recognition device, and robot |
| CN110693469B (en) * | 2019-10-08 | 2020-12-08 | 华中科技大学 | Electronic skin with graded peak pressure structure and preparation method thereof |
| CN110726364B (en) * | 2019-11-01 | 2021-07-20 | 湘潭大学 | Flexible strain sensor with strain isolation effect |
| CN111256888B (en) * | 2020-03-02 | 2022-06-10 | 吉林大学 | Bionic multilevel structure flexible stress and strain combined sensor and preparation method thereof |
| CN115112276A (en) * | 2022-06-27 | 2022-09-27 | 湃瑞电子科技(苏州)有限公司 | Pressure sensor |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106531733A (en) * | 2016-12-21 | 2017-03-22 | 清华大学 | Flexible pressure sensor and preparation method therefor |
| CN108469319A (en) * | 2018-03-20 | 2018-08-31 | 西南交通大学 | A kind of flexible force sensitive sensor and preparation method thereof, array device and application |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11248557A (en) * | 1998-02-28 | 1999-09-17 | Porimatec Kk | Pressure-sensitive conductive sensor |
| US7615206B2 (en) * | 2006-08-11 | 2009-11-10 | Georgia Tech Research Corporation | Methods of fabricating nanoscale-to-microscale structures |
| CN101710090A (en) * | 2009-11-27 | 2010-05-19 | 上海理工大学 | Nano chemical sensor based on semiconductor nanowire and capable of supplying power by self and preparation method thereof |
| WO2015083874A1 (en) * | 2013-12-03 | 2015-06-11 | 재단법인 멀티스케일 에너지시스템 연구단 | High-sensitivity sensor comprising conductive thin film containing cracks and method for manufacturing same |
| CN104523231B (en) * | 2014-12-24 | 2017-07-21 | 上海集成电路研发中心有限公司 | Pliable pressure sensing part, sensor and its manufacture method |
| CN106153178A (en) * | 2015-03-17 | 2016-11-23 | 中国科学院苏州纳米技术与纳米仿生研究所 | Compliant conductive vibrating diaphragm, flexible vibration sensor and its preparation method and application |
| CN105277514A (en) * | 2015-11-25 | 2016-01-27 | 厦门大学 | Visible light refractive index sensor and machining method thereof |
| KR101898604B1 (en) * | 2015-11-30 | 2018-09-13 | 재단법인 멀티스케일 에너지시스템 연구단 | Highly sensitive sensor comprising linear crack pattern and process for preparing same |
| CN105783697B (en) * | 2016-05-18 | 2018-08-14 | 郑州大学 | Flexible strain transducer with crack structtire and preparation method thereof |
| CN106644189B (en) * | 2016-12-13 | 2018-12-07 | 中国科学院深圳先进技术研究院 | Pliable pressure sensor and preparation method thereof |
| CN108444377B (en) * | 2018-03-18 | 2019-10-01 | 吉林大学 | Rule-based micron crackle array structure flexibility strain transducer and preparation method thereof |
-
2019
- 2019-01-16 CN CN201910041452.7A patent/CN109655180B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106531733A (en) * | 2016-12-21 | 2017-03-22 | 清华大学 | Flexible pressure sensor and preparation method therefor |
| CN108469319A (en) * | 2018-03-20 | 2018-08-31 | 西南交通大学 | A kind of flexible force sensitive sensor and preparation method thereof, array device and application |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109655180A (en) | 2019-04-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109655180B (en) | Flexible pressure sensor based on crack array structure and preparation method thereof | |
| Kang et al. | Fingerprint‐inspired conducting hierarchical wrinkles for energy‐harvesting E‐skin | |
| CN108444377B (en) | Rule-based micron crackle array structure flexibility strain transducer and preparation method thereof | |
| Qiu et al. | Ionic skin with biomimetic dielectric layer templated from calathea zebrine leaf | |
| CN105758562B (en) | A kind of pliable pressure sensor and preparation method thereof | |
| Wang et al. | Self‐powered high‐resolution and pressure‐sensitive triboelectric sensor matrix for real‐time tactile mapping | |
| CN108775979A (en) | A kind of high sensitivity pliable pressure sensor and preparation method thereof | |
| CN110455445B (en) | Flexible stress sensor and preparation method thereof | |
| Vuorinen et al. | Printable, transparent, and flexible touch panels working in sunlight and moist environments | |
| CN109556768B (en) | Pressure sensor and preparation method thereof | |
| Liu et al. | Thin, skin‐integrated, stretchable triboelectric nanogenerators for tactile sensing | |
| CN104374486B (en) | A kind of flexibility temperature sensor and preparation method thereof based on graphene nano wall | |
| CN101226161B (en) | Preparation method of polymethyl methacrylate/polyaniline nano fibre composite resistor type film gas sensor | |
| CN107966481B (en) | A kind of Material Identification sensor and preparation method thereof based on composite capacitive structure | |
| CN111982162A (en) | Flexible capacitive proximity-touch dual-mode sensing array and preparation method thereof | |
| CN208350249U (en) | A kind of high sensitivity pliable pressure sensor | |
| CN108613757B (en) | Flexible capacitive touch sensor based on biological material chitosan film and preparation method thereof | |
| CN106946221A (en) | Pliable pressure sensor production method based on " V " type groove array electrode | |
| Hu et al. | A flexible capacitive tactile sensor array with micro structure for robotic application | |
| Zhou et al. | Metal mesh as a transparent omnidirectional strain sensor | |
| CN105361977A (en) | Resistive flexible transparent joint electronic skin and production method and application thereof | |
| CN110118624A (en) | A kind of pressure sensor and preparation method thereof | |
| CN113091811A (en) | Flexible temperature and pressure integrated sensor and preparation method and application thereof | |
| CN112504518A (en) | Flexible capacitive pressure sensor and preparation method thereof | |
| Buchberger et al. | Transparent, flexible, thin sensor surfaces for passive light-point localization based on two functional polymers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |