Flexible pressure sensor and preparation method thereof

Abstract

The invention relates to the technical field of sensors, and discloses a flexible pressure sensor and a preparation method thereof.The flexible pressure sensor comprises a flexible substrate, liquid metal and a first flexible stretch-resistant film, the flexible substrate is internally provided with a closed metal flow channel, the liquid metal is arranged in the metal flow channel, the flexible substrate is provided with a pressure sensing area, and the first flexible stretch-resistant film is arranged in the pressure sensing area; the pressure sensing area is provided with a first pressure sensing face, and the first flexible stretch-resistant film is fixed to the first pressure sensing face in an overlapped mode. The flexible pressure sensor provided by the invention can solve the problem of low pressure measurement accuracy caused by interference on pressure measurement due to resistance change of liquid metal caused by tensile deformation of the flexible pressure sensor in a pressure measurement process in related technologies.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a flexible pressure sensor and a preparation method thereof. Background Art

[0002] Flexible pressure sensors are devices that convert pressure signals into electrical signals and are widely used in wearable devices, human-computer interaction, and electronic skin.

[0003] Liquid metal can still maintain good electrical properties under large deformation, so it is widely used in flexible pressure sensors. When using flexible pressure sensors for pressure measurement, external pressure acts on the flexible pressure sensor to cause it to deform. The deformation causes the resistance of the liquid metal to change. The change in the resistance of the liquid metal is used to obtain the change in external pressure, thereby completing the pressure measurement.

[0004] However, stretching can also cause the flexible pressure sensor to deform, and the stretching deformation will also change the resistance of the liquid metal, thereby interfering with the pressure measurement and causing inaccurate pressure measurement. Summary of the invention

[0005] The present invention provides a flexible pressure sensor and a preparation method thereof, which are used to solve the problem in the related art that, during the pressure measurement process, the tensile deformation of the flexible pressure sensor causes the resistance change of liquid metal, which interferes with the pressure measurement and leads to low pressure measurement accuracy.

[0006] The present invention provides a flexible pressure sensor, comprising a flexible substrate, liquid metal and a first flexible anti-stretching film, wherein a closed metal flow channel is provided in the flexible substrate, the liquid metal is arranged in the metal flow channel, the flexible substrate has a pressure sensing area, the area where the metal flow channel is located forms the pressure sensing area, the pressure sensing area has a first pressure sensing surface, and the first flexible anti-stretching film is superimposed and fixed on the first pressure sensing surface.

[0007] According to the flexible pressure sensor provided by the present invention, the flexible pressure sensor also includes a second flexible anti-stretching film, which is stacked and fixed on the second pressure sensing surface of the pressure sensing area, and the second pressure sensing surface and the first pressure sensing surface are arranged opposite to each other.

[0008] According to the flexible pressure sensor provided by the present invention, the first flexible anti-stretching film is bonded to the first pressure sensing surface, and the second flexible anti-stretching film is bonded to the second pressure sensing surface; or,

[0009] The first flexible anti-stretching film is bonded to the first pressure sensing surface, and the second flexible anti-stretching film is bonded to the second pressure sensing surface.

[0010] According to the flexible pressure sensor provided by the present invention, the flexible substrate further comprises an extension area, and the extension area is connected to the outer periphery of the pressure sensing area.

[0011] According to the flexible pressure sensor provided by the present invention, the flexible substrate is provided with a liquid filling hole, and the liquid filling hole is connected to the metal flow channel. The flexible pressure sensor also includes a wire, one end of the wire extends into the metal flow channel through the liquid filling hole and contacts the liquid metal, the other end of the wire is located outside the flexible substrate, and the wire is fixedly connected to the first flexible anti-stretching film.

[0012] The present invention also provides a method for preparing a flexible pressure sensor, the method comprising:

[0013] preparing a first flexible base having a groove structure;

[0014] Overlaying and fixing a first flexible stretch-resistant film on the first surface of the first flexible base, with the first flexible stretch-resistant film being opposite to the area where the groove structure is located;

[0015] The second flexible base is stacked and fixed on the second surface of the first flexible base, so that the first flexible base and the second flexible base are connected to form a flexible base, the second surface is opposite to the first surface, and the second flexible base blocks the notch of the groove structure to form a metal flow channel;

[0016] pouring liquid metal into the metal flow channel;

[0017] Inserting a first end of a wire into the liquid metal, wherein a second end of the wire is located outside the flexible substrate;

[0018] The wire is fixedly connected to the first flexible anti-stretching film.

[0019] According to the preparation method provided by the present invention, after the first flexible stretch-resistant film is superimposed and fixed on the first surface of the first flexible base, and before the second flexible base is superimposed and fixed on the second surface of the first flexible base, the preparation method further comprises:

[0020] A liquid filling hole is provided on the first flexible anti-stretching film and the first flexible base, and the liquid filling hole passes through the groove structure.

[0021] According to the preparation method provided by the present invention, after the second flexible base is stacked and fixed on the second surface of the first flexible base, and before the liquid metal is poured into the metal flow channel, the preparation method further includes:

[0022] A second flexible anti-stretching film is stacked and fixed on a surface of the second flexible base that is away from the first flexible base, and the second flexible anti-stretching film is opposite to the area where the metal runner is located.

[0023] According to the preparation method provided by the present invention, the first flexible stretch-resistant film is stacked and fixed on the first surface of the first flexible base, comprising:

[0024] Plasma-treating the first flexible anti-stretching film and the first surface of the first flexible base, and laminating the first flexible anti-stretching film on the first surface, so that the first flexible anti-stretching film and the first flexible base are bonded and connected;

[0025] The method of stacking and fixing the second flexible base on the second surface of the first flexible base comprises:

[0026] Plasma-treating the second surface of the second flexible base and the first flexible base, and attaching the second flexible base to the second surface, so that the second flexible base and the first flexible base are bonded and connected;

[0027] The method of stacking and fixing a second flexible stretch-resistant film on a surface of the second flexible base that faces away from the first flexible base comprises:

[0028] The surface of the second flexible base facing away from the first flexible base and the second flexible stretch-resistant film are plasma treated, and the second flexible stretch-resistant film is adhered to the surface of the second flexible base facing away from the first flexible base, so that the second flexible stretch-resistant film is bonded to the second flexible base.

[0029] According to the preparation method provided by the present invention, the preparation of the first flexible base having a groove structure comprises:

[0030] Coating photoresist on silicon wafer;

[0031] Covering the photoresist with a mask;

[0032] Exposing the photoresist covered with the mask to ultraviolet light;

[0033] removing the mask;

[0034] Using a developer to wash the photoresist so as to form a photolithography structure on the silicon wafer;

[0035] pouring a flexible substrate prepolymer on the silicon wafer having the photolithography structure, and baking the flexible substrate prepolymer to form a first flexible base with the flexible substrate prepolymer;

[0036] The first flexible base is peeled off from the silicon wafer.

[0037] According to the preparation method provided by the present invention, the flexible substrate includes a pressure sensing area and an extension area, the extension area is connected to the outer periphery of the pressure sensing area, and the area where the metal runner is located forms the pressure sensing area.

[0038] In the embodiment of the present invention, the first flexible anti-stretching film limits the tensile deformation of the pressure sensing area connected thereto, that is, the pressure sensing area is not prone to tensile deformation, so that the flexible pressure sensor in the present invention has a good ability to resist tensile interference, alleviates the problem that the resistance of the liquid metal changes due to tensile deformation of the flexible pressure sensor, thereby interfering with the pressure measurement, and improves the pressure measurement accuracy of the flexible pressure sensor. It can be seen that the flexible pressure sensor of the present invention can solve the problem in the related art that during the pressure measurement process, the tensile deformation of the flexible pressure sensor causes the resistance change of the liquid metal to interfere with the pressure measurement, resulting in low pressure measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 is a structural schematic diagram of the flexible pressure sensor provided by the present invention;

[0041] Figure 2 Schematic diagram of the structure of the flexible pressure sensor in a stretched state provided by the present invention ( Figure 2 The arrow direction in the figure indicates the direction in which the flexible sensor is stretched. Figure 2 The dotted box in the figure indicates the position of the flexible substrate when it is not stretched).

[0042] Figure 3 It is a structural schematic diagram of the metal runner provided by the present invention;

[0043] Figure 4 It is a schematic structural diagram of a silicon wafer coated with a photoresist provided by the present invention;

[0044] Figure 5 It is a schematic structural diagram of a photoresist covered with a mask provided by the present invention being exposed under ultraviolet light;

[0045] Figure 6 It is a schematic structural diagram of a silicon wafer with a photolithography structure provided by the present invention;

[0046] Figure 7 It is a schematic diagram of the matching structure of the first flexible base, the photolithography structure and the silicon wafer provided by the present invention;

[0047] Figure 8 is a structural schematic diagram of a first flexible base with a groove structure provided by the present invention;

[0048] Fig. 9 is a schematic diagram of plasma treatment of a first flexible base and a first flexible anti-stretching film provided by the present invention;

[0049] Fig.10 It is a schematic structural diagram of a first flexible anti-stretching film and a first flexible base that are stacked and connected to each other provided by the present invention;

[0050] Fig.11 Schematic diagram of the structure of the present invention after a liquid filling hole is opened on the first flexible stretch-resistant film and the first flexible base which are stacked and connected ( Fig.11 The direction of the arrow in the figure refers to the direction in which the filling hole is opened);

[0051] Fig.12 It is a schematic diagram of plasma processing of a first flexible base and a second flexible base provided by the present invention;

[0052] Fig.13 It is a schematic diagram of the matching structure of the first flexible stretch-resistant film and the flexible substrate provided by the present invention;

[0053] Fig.14 is a schematic diagram of plasma treatment of the second flexible anti-stretching film and the second flexible base provided by the present invention;

[0054] Fig.15 It is a schematic diagram of the matching structure of the first flexible anti-stretching film, the second flexible anti-stretching film and the flexible substrate provided by the present invention;

[0055] Fig.16 It is a schematic diagram of the matching structure of the first flexible anti-stretching film, the second flexible anti-stretching film, the flexible substrate and the liquid metal after the liquid metal is poured into the film provided by the present invention;

[0056] Fig.17 is a flow chart of the preparation of the flexible pressure sensor provided by the present invention;

[0057] Fig.18 It is a flow chart of preparing a first flexible base with a groove structure provided by the present invention.

[0058] Reference numerals:

[0059] 100, flexible substrate; 110, pressure sensing area; 120, extension area; 130, metal flow channel; 140, first flexible base; 141, groove structure; 150, second flexible base;

[0060] 200, Liquid Metal;

[0061] 310, a first flexible anti-stretching film; 320, a second flexible anti-stretching film;

[0062] 400, filling hole;

[0063] 610, silicon wafer; 620, photoresist; 630, mask; 631, light-transmitting area; 632, light-shielding area; 640, ultraviolet light. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] Please refer to Figures 1 to 3 The present invention discloses a flexible pressure sensor, which includes a flexible substrate 100, a liquid metal 200 and a first flexible anti-stretching film 310.

[0066] A closed metal flow channel 130 is provided in the flexible substrate 100, and the liquid metal 200 is encapsulated in the metal flow channel 130. The deformation of the flexible substrate 100 under pressure will cause the liquid metal 200 to be deformed under pressure, so that the liquid metal 200 produces a change in resistance, thereby responding to the pressure in the area in the form of a change in resistance caused by pressure deformation. The flexible substrate 100 has a pressure sensing area 110, and the area where the metal flow channel 130 is located forms the pressure sensing area 110. The pressure sensing area 110 has a first pressure sensing surface, and the first flexible anti-stretching film 310 is superimposed and fixed on the first pressure sensing surface.

[0067] The first flexible anti-stretching film 310 is not stretchable, thereby limiting the tensile deformation of the pressure sensing area 110 fixedly connected to the first flexible anti-stretching film 310, so that the pressure sensing area 110 has the effect of resisting tensile deformation. Therefore, the liquid metal 200 located in the pressure sensing area 110 is not easy to produce a change in resistance when subjected to a tensile effect, and the first flexible anti-stretching film 310 does not affect the compressive deformation of the pressure sensing area 110, and also does not affect the pressure measurement of the flexible pressure sensor, so that the flexible pressure sensor in the present invention can resist the influence of tensile action on pressure measurement, thereby improving the accuracy of pressure measurement.

[0068] Optionally, the material of the flexible substrate 100 may be PDMS (polydimethylsiloxane), the material of the flexible substrate 100 may also be Ecoflex (aliphatic aromatic random copolyester), of course, the flexible substrate 100 may also be made of other flexible and elastic materials, which is not limited in this article. The first flexible anti-stretching film 310 may be a PI (polyimide) film, which is not stretchable, the first flexible anti-stretching film 310 may also be a PET (polyethylene glycol terephthalate) film, of course, the first flexible anti-stretching film 310 may also be other non-stretchable films.

[0069] In the embodiment of the present invention, the first flexible anti-stretching film 310 limits the tensile deformation of the pressure sensing area 110 connected thereto, that is, the pressure sensing area 110 is not easily tensile deformed, so that the flexible pressure sensor in the present invention has a good ability to resist tensile interference, alleviates the problem that the resistance of the liquid metal 200 changes due to tensile deformation of the flexible pressure sensor, thereby interfering with the pressure measurement, and improves the pressure measurement accuracy of the flexible pressure sensor. The flexible pressure sensor of this structure is simple and reliable, and has high working stability. It can be seen that the flexible pressure sensor of the present invention can solve the problem in the related art that the tensile deformation of the flexible pressure sensor interferes with the pressure measurement, resulting in low pressure measurement accuracy of the flexible pressure sensor.

[0070] In a further technical solution, the flexible pressure sensor may further include a second flexible anti-stretching film 320, which may be superimposed and fixed on the second pressure sensing surface of the pressure sensing area 110, and the second pressure sensing surface and the first pressure sensing surface are arranged opposite to each other. In this case, the tensile deformation of the two opposite surfaces of the pressure sensing area 110 is restricted, which can further improve the restriction on the tensile deformation of the pressure sensing area 110, thereby further alleviating the problem that the resistance of the liquid metal 200 changes due to tensile deformation of the flexible pressure sensor, thereby interfering with the pressure measurement, and further improving the pressure measurement accuracy of the flexible pressure sensor.

[0071] When the flexible pressure sensor is applied to fields such as wearable devices, the flexible pressure sensor may need to be bent and deformed. For this reason, in an embodiment of the present invention, the flexible substrate 100 may further include an extension area 120, which may be connected to the outer periphery of the pressure sensing area 110. The extension area 120 of the flexible substrate 100 is not connected to the first flexible anti-stretching film 310 and the second flexible anti-stretching film 320, so the extension area 120 of the flexible substrate 100 can be stretched and deformed. The pressure sensing area 110 and the extension area 120 may be an integrated structure. When the flexible pressure sensor is not subjected to a stretching effect, the pressure sensing area 110 and the extension area 120 may be coplanar.

[0072] In this case, the extension area 120 of the flexible substrate 100 can be stretched and deformed, so that the flexible pressure sensor can be bent and deformed, so that the flexible pressure sensor can be applied to occasions or devices that require bending and deformation.

[0073] In an embodiment of the present invention, the extension area 120 enables the flexible pressure sensor to produce tensile deformation, so that the flexible pressure sensor can be used in situations where it needs to bend and deform. The pressure sensing area 110 of the flexible pressure sensor is resistant to tensile deformation, thereby alleviating the effect of tensile deformation on the resistance of the liquid metal 200, so that the flexible pressure sensor still has high pressure measurement accuracy under larger tensile deformation.

[0074] In the above solution, the first flexible anti-stretching film 310 and the second flexible anti-stretching film 320 are both connected to the pressure sensing area 110 . There are many ways to achieve fixed connection between the first flexible anti-stretching film 310 and the second flexible anti-stretching film 320 and the pressure sensing area 110 .

[0075] In an optional embodiment, the first flexible anti-stretching film 310 may be bonded to the first pressure sensing surface, and the first flexible anti-stretching film 310 may be bonded to the first pressure sensing surface of the pressure sensing area 110 by plasma bonding. The second flexible anti-stretching film 320 may be bonded to the second pressure sensing surface, and the second flexible anti-stretching film 320 may be bonded to the second pressure sensing surface of the pressure sensing area 110 by plasma bonding.

[0076] In this case, the first flexible anti-stretching film 310 and the second flexible anti-stretching film 320 are bonded to the pressure sensing area 110 by plasma bonding, so that the first flexible anti-stretching film 310 and the second flexible anti-stretching film 320 can be tightly connected to the pressure sensing area 110 .

[0077] In another optional embodiment, the first flexible anti-stretching film 310 may be bonded and connected to the first pressure sensing surface by glue, and the second flexible anti-stretching film 320 may be bonded and connected to the second pressure sensing surface by glue.

[0078] In another optional embodiment, when the pressure sensing area 110 is in a semi-solid state, the first flexible anti-stretching film 310 can be attached to the first pressure sensing surface to achieve a fixed connection between the first pressure sensing surface and the first flexible anti-stretching film 310. When the pressure sensing area 110 is in a semi-solid state, the second flexible anti-stretching film 320 can be attached to the second pressure sensing surface to achieve a fixed connection between the second pressure sensing surface and the second flexible anti-stretching film 320.

[0079] In order to output the resistance change of the liquid metal 200, the flexible substrate 100 may be provided with a liquid filling hole 400, which may be connected to the metal flow channel 130. The flexible pressure sensor may also include a wire, one end of which may extend into the metal flow channel 130 through the liquid filling hole 400 and contact the liquid metal 200, and the other end of the wire may be located outside the flexible substrate 100, and the wire may be connected to the first flexible anti-stretching film 310 by means of an adhesive connection or the like. In this case, the connection stability between the wire and the liquid metal 200 can be achieved, and the displacement of the wire relative to the flexible substrate 100 may be avoided, resulting in the wire and the liquid metal 200 being separated.

[0080] Optionally, the conductive wire may be a copper wire, and the conductive wire may be connected to the first flexible anti-stretching film 310 via an adhesive, and the adhesive may be 705 silicone.

[0081] In order to achieve the blocking of the filling hole 400, in an optional embodiment, the outer surface of the wire can be sealed and fitted with the hole wall of the filling hole 400, thereby blocking the filling hole 400 and preventing the leakage of the liquid metal 200. In an optional embodiment, a sealing ring can be provided between the wire and the hole wall of the filling hole 400 to prevent the leakage of the liquid metal 200.

[0082] In another optional embodiment, the adhesive used to connect the wire and the first flexible anti-stretching film 310 can penetrate into the portion of the filling hole 400 corresponding to the first flexible anti-stretching film 310, thereby blocking the filling hole 400 and preventing the leakage of the liquid metal 200, but the adhesive does not penetrate into the portion of the filling hole 400 corresponding to the flexible substrate 100, so as to avoid affecting the performance of the liquid metal 200.

[0083] When bonding the wire and the first flexible anti-stretching film 310, the adhesive can be coated on the first flexible anti-stretching film 310 and coated around the wire so that the wire is bonded and fixed to the first flexible anti-stretching film 310. Since the gap between the wire and the liquid filling hole 400 is small, the viscosity of the adhesive is large. By controlling the amount of the adhesive, the adhesive can penetrate into the portion of the liquid filling hole 400 corresponding to the first flexible anti-stretching film 310, but will not penetrate into the portion of the liquid filling hole 400 corresponding to the flexible substrate 100.

[0084] Please refer to Figures 4 to 18 The present invention also discloses a method for preparing a flexible pressure sensor, the disclosed preparation method comprising:

[0085] Step S101 : preparing a first flexible base 140 having a groove structure 141 .

[0086] The shape of the groove structure 141 is consistent with the shape of the metal flow channel 130 required by the flexible pressure sensor, and this document does not limit the shape of the groove structure 141.

[0087] Step S102 : The first flexible anti-stretching film 310 is stacked and fixed on the first surface of the first flexible base 140 , and the first flexible anti-stretching film 310 is opposite to the area where the groove structure 141 is located.

[0088] That is, the first flexible stretch-resistant film 310 is overlapped and fixed to the area where the groove structure 141 of the first flexible base 140 is located. It should be noted that the first surface is the surface of the first flexible base 140 away from the notch of the groove structure 141 .

[0089] Step S103: The second flexible base 150 is stacked and fixed on the second surface of the first flexible base 140 so that the first flexible base 140 and the second flexible base 150 are connected to form a flexible substrate 100, the second surface is opposite to the first surface, and the second flexible base 150 blocks the notch of the groove structure 141 to form a metal flow channel 130.

[0090] It should be noted that the second surface is the surface where the slot opening of the slot structure 141 is located.

[0091] Step S104 : pouring liquid metal 200 into the metal flow channel 130 .

[0092] Applying pressure to the area where the metal flow channel 130 is located causes the resistance of the liquid metal 200 to change, thereby achieving pressure measurement.

[0093] Step S105 : inserting a first end of the wire into the liquid metal 200 , and placing a second end of the wire outside the flexible substrate 100 .

[0094] Optionally, the outer surface of the wire can be sealed against the inner wall of the filling hole 400, thereby blocking the filling hole 400 and preventing leakage of the liquid metal 200. Of course, a sealing ring can also be installed between the wire and the hole wall of the filling hole 400 to prevent leakage of the liquid metal 200.

[0095] Step S106 : fixing the wire to the first flexible anti-stretching film 310 .

[0096] Optionally, the wire may be a copper wire, which may be connected to the first flexible anti-stretching film 310 via an adhesive, the adhesive may be 705 silicone, and the adhesive may penetrate into the filling hole 400 of the first flexible anti-stretching film 310, thereby also playing the role of sealing the filling hole 400 and preventing leakage of the liquid metal 200.

[0097] When bonding the wire and the first flexible anti-stretching film 310, the adhesive can be coated on the first flexible anti-stretching film 310 and coated around the wire so that the wire is bonded and fixed to the first flexible anti-stretching film 310. When there is a gap between the wire and the filling hole 400, the adhesive can penetrate into the filling hole 400 of the first flexible anti-stretching film 310 to seal the filling hole 400 and prevent the liquid metal 200 from leaking. Since the adhesive has a high viscosity, controlling the amount of the adhesive can prevent the adhesive from penetrating into the filling hole 400 of the flexible substrate 100.

[0098] In an embodiment of the present invention, a first flexible anti-stretching film 310 is superimposed and fixed on the surface of the flexible substrate 100 obtained by the above-mentioned preparation method. The first flexible anti-stretching film 310 is non-stretchable, so that the tensile deformation of the part of the flexible substrate 100 fixedly connected to the first flexible anti-stretching film 310 is restricted, and because the first flexible anti-stretching film 310 is opposite to the metal flow channel 130, the area where the metal flow channel 130 is located is not easy to produce tensile deformation, and the liquid metal 200 in the metal flow channel 130 is not easy to produce changes in resistance due to tensile deformation, thereby alleviating the problem that the resistance of the liquid metal 200 of the flexible pressure sensor changes due to tensile deformation, thereby interfering with the pressure measurement, thereby improving the pressure measurement accuracy of the flexible pressure sensor.

[0099] In the above solution, it is necessary to pour liquid metal 200 into the metal flow channel 130. Since the second flexible base 150 blocks the notch of the groove structure 141, the metal flow channel 130 is a closed metal flow channel 130. In order to pour liquid metal 200 into the metal flow channel 130, in an optional embodiment, a pouring hole 400 can be opened on the flexible substrate 100, and liquid metal 200 can be poured into the metal flow channel 130 through the pouring hole 400. However, the pouring hole 400 opened on the flexible substrate 100 is easy to penetrate the flexible substrate 100, which makes it difficult to plug the pouring hole 400 later.

[0100] In an embodiment of the present invention, after the above-mentioned step of stacking and fixing the first flexible anti-stretching film 310 on the first surface of the first flexible base 140, and before the above-mentioned step of stacking and fixing the second flexible base 150 on the second surface of the first flexible base 140, the preparation method may further include:

[0101] Step A1: a liquid filling hole 400 is opened on the first flexible anti-stretching film 310 and the first flexible base 140 , and the liquid filling hole 400 passes through the groove structure 141 .

[0102] In this case, before the first flexible base 140 and the second flexible base 150 are connected to form the flexible substrate 100, holes are punched on the first flexible anti-stretching film 310 and the first flexible base 140. This can avoid the problem of the filling hole 400 penetrating the entire flexible substrate 100 during the hole drilling process, and facilitates the subsequent blocking of the filling hole 400.

[0103] In order to better alleviate the problem that the resistance change of the liquid metal 200 caused by the stretching deformation of the flexible substrate 100 causes interference with the pressure measurement result, after the above step of stacking and fixing the second flexible base 150 on the second surface of the first flexible base 140, and before the above step of pouring the liquid metal 200 into the metal flow channel 130, the preparation method may further include:

[0104] Step B1: The second flexible anti-stretching film 320 is stacked and fixed on the surface of the second flexible base 150 facing away from the first flexible base 140 , and the second flexible anti-stretching film 320 is opposite to the area where the metal runner 130 is located.

[0105] In this case, the first flexible anti-stretching film 310 and the second flexible anti-stretching film 320 are respectively stacked and fixed on two opposite surfaces of the flexible substrate 100, and the first flexible anti-stretching film 310 and the second anti-stretching film are opposite to the metal runner 130, so that the tensile deformation of the two surfaces of the flexible substrate 100 opposite to the metal runner 130 is restricted, which can further enhance the restriction on the tensile deformation of the flexible substrate 100 opposite to the metal runner 130, thereby further reducing the interference of the tensile deformation of the flexible pressure sensor on the pressure measurement.

[0106] In the embodiment of the present invention, there are various methods for stacking and fixing the first flexible anti-stretching film 310 on the first surface of the first flexible base 140 in the above steps.

[0107] In an optional embodiment, the surface of the first flexible anti-stretching film 310 that needs to be connected to the first flexible base 140 and the first surface of the first flexible base 140 can be plasma treated, that is, a layer of activated groups is introduced into the surface of the first flexible anti-stretching film 310 that needs to be connected to the first flexible base 140 and the first surface of the first flexible base 140, and then the first flexible anti-stretching film 310 after plasma treatment is adhered to the first surface, so that the first flexible anti-stretching film 310 and the first flexible base 140 are bonded and connected.

[0108] In another optional embodiment, an adhesive may be used to adhere and fix the first flexible stretch-resistant film 310 to the first surface of the first flexible base 140 to achieve overlapping and fixing of the two.

[0109] In another optional embodiment, when the first flexible base 140 is in a semi-cured state, the first flexible stretch-resistant film 310 may be attached to the first surface of the first flexible base 140 to achieve overlapping and fixing of the two.

[0110] In the embodiment of the present invention, there are various methods for stacking and fixing the second flexible base 150 on the second surface of the first flexible base 140 in the above steps.

[0111] In an optional embodiment, the surface of the second flexible base 150 that needs to be connected to the first flexible base 140 and the second surface of the first flexible base 140 can be plasma treated, that is, a layer of activated groups is formed on the surface of the second flexible base 150 that needs to be connected to the first flexible base 140 and the second surface of the first flexible base 140, and the second flexible base 150 after plasma treatment is adhered to the second surface after plasma treatment, so that the second flexible base 150 and the first flexible base 140 are bonded and connected.

[0112] In another optional embodiment, the second flexible base 150 may be bonded and fixed to the second surface of the first flexible base 140 using an adhesive to achieve overlapping fixation of the two.

[0113] In another optional embodiment, the first flexible base 140 and the second flexible base 150 may be attached to each other when they are in a semi-cured state, so as to achieve overlapping and fixing of the two.

[0114] In the embodiment of the present invention, there are various methods for stacking and fixing the second flexible anti-stretching film 320 on the surface of the second flexible base 150 facing away from the first flexible base 140 in the above steps.

[0115] In an optional embodiment, the surface of the second flexible base 150 facing away from the first flexible base 140 and the second flexible stretch-resistant film 320 may be plasma treated, that is, a layer of activated groups is formed on the surface of the second flexible base 150 facing away from the first flexible base 140 and the surface of the second flexible stretch-resistant film 320, and then the plasma-treated surface of the second flexible stretch-resistant film 320 is adhered to the surface of the second flexible base 150 facing away from the first flexible base 140, so that the second flexible stretch-resistant film 320 is bonded to the second flexible base 150.

[0116] In another optional embodiment, an adhesive may be used to adhere and fix the second flexible stretch-resistant film 320 to the surface of the second flexible base 150 facing away from the first flexible base 140 , so as to achieve overlapping and fixing of the two.

[0117] In another optional embodiment, when the second flexible base 150 is in a semi-cured state, the second flexible stretch-resistant film 320 may be attached to the surface of the second flexible base 150 facing away from the first flexible base 140 to achieve overlapping and fixing of the two.

[0118] The method for preparing the first flexible base 140 having the groove structure 141 in the above steps may include:

[0119] Step S201 : coating a photoresist 620 on a silicon wafer 610 .

[0120] The photoresist 620 may be SU-8 photoresist. After the photoresist 620 is coated on the silicon wafer 610 , the photoresist 620 may be baked for the first time to enhance the connection strength between the photoresist 620 and the silicon wafer 610 .

[0121] Step S202 : Covering the photoresist 620 with a mask 630 .

[0122] The mask 630 includes a light-transmitting area 631 and a light-shielding area 632 . The shape of the light-transmitting area 631 is consistent with the shape of the required metal runner 130 .

[0123] Step S203: Expose the photoresist 620 covered with the mask 630 to ultraviolet light 640.

[0124] The ultraviolet light 640 can penetrate the light-transmitting area 631 and irradiate the photoresist 620, thereby curing the irradiated photoresist 620. However, the ultraviolet light 640 cannot penetrate the light-shielding area 632 of the mask 630, thereby preventing the photoresist 620 opposite to the light-shielding area 632 from being cured.

[0125] Step S204: removing the mask 630.

[0126] After the mask 630 is removed from the photoresist 620 , the photoresist 620 may be baked again to further promote the photocuring reaction of the photoresist 620 .

[0127] Step S205 : using a developer to rinse the photoresist 620 , so as to form a photolithography structure on the silicon wafer 610 .

[0128] The developer can dissolve the uncured photoresist 620 , while the cured photoresist 620 cannot be dissolved by the developer and remains on the silicon wafer 610 to form a photolithography structure.

[0129] After the above steps S201 , S202 , S203 , S204 and S205 , a photolithography structure with a specific shape is manufactured on the silicon wafer 610 through the soft photolithography process.

[0130] Step S206 : pouring a flexible substrate prepolymer onto the silicon wafer 610 having the photolithography structure, and baking the flexible substrate prepolymer to form the first flexible base 140 with the flexible substrate prepolymer.

[0131] The flexible substrate prepolymer can be prepared by mixing a PDMS base agent and a curing agent in a ratio of 10:1. After the flexible substrate prepolymer is baked, the flexible substrate prepolymer can be cured to form a first flexible base 140, and the region with the photolithography structure on the silicon wafer 610 forms a groove structure 141.

[0132] Step S207 : peeling the first flexible base 140 from the surface of the silicon wafer 610 .

[0133] The first flexible base 140 is peeled off from the silicon wafer 610 to obtain the first flexible substrate 100 having the groove structure 141, and the shape of the groove structure 141 is the same as the shape of the photolithography structure. Step S206 and step S207 can also be referred to as the process of flexible substrate reverse molding (PDMS reverse molding). In this way, the first flexible base 140 having the groove structure 141 is obtained by the method of soft photolithography and flexible substrate reverse molding (PDMS reverse molding).

[0134] The flexible base may include a pressure sensing area 110 and an extension area 120, the extension area 120 may be connected to the outer periphery of the pressure sensing area 110, the area where the metal runner 130 is located forms the pressure sensing area 110, and the first flexible anti-stretching film 310 and the second flexible anti-stretching film 320 are respectively stacked and fixed on two opposite surfaces of the pressure sensing area 110. In this case, the extension area 120 is not provided with the first flexible anti-stretching film 310 and the second flexible anti-stretching film 320, so that the extension area 120 domain can be stretched and deformed, so that the flexible pressure sensor can be bent and deformed, which is convenient for applying the flexible pressure sensor to occasions requiring bending and deformation.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible pressure sensor, characterized in that: The invention comprises a flexible substrate (100), liquid metal (200) and a first flexible anti-stretching film (310), wherein a closed metal flow channel (130) is provided in the flexible substrate (100), the liquid metal (200) is arranged in the metal flow channel (130), the flexible substrate (100) has a pressure sensing area (110), the area where the metal flow channel (130) is located forms the pressure sensing area (110), the pressure sensing area (110) has a first pressure sensing surface, and the first flexible anti-stretching film (310) is superimposed and fixed on the first pressure sensing surface.

2. The flexible pressure sensor according to claim 1, characterized in that: The flexible pressure sensor further comprises a second flexible anti-stretching film (320), wherein the second flexible anti-stretching film (320) is stacked and fixed on a second pressure sensing surface of the pressure sensing area (110), and the second pressure sensing surface and the first pressure sensing surface are arranged opposite to each other.

3. The flexible pressure sensor according to claim 2, characterized in that: The first flexible anti-stretching film (310) is bonded to the first pressure sensing surface, and the second flexible anti-stretching film (320) is bonded to the second pressure sensing surface; or, The first flexible anti-stretching film (310) is bonded to the first pressure sensing surface, and the second flexible anti-stretching film (320) is bonded to the second pressure sensing surface.

4. The flexible pressure sensor according to claim 1, characterized in that: The flexible substrate (100) further comprises an extension area (120), wherein the extension area (120) is connected to the outer periphery of the pressure sensing area (110).

5. The flexible pressure sensor according to claim 1, characterized in that: The flexible substrate (100) is provided with a liquid filling hole (400), and the liquid filling hole (400) is connected to the metal flow channel (130). The flexible pressure sensor also includes a wire, one end of which extends into the metal flow channel (130) through the liquid filling hole (400) and contacts the liquid metal (200), and the other end of the wire is located outside the flexible substrate (100), and the wire is fixedly connected to the first flexible anti-stretching film (310).

6. A method for preparing a flexible pressure sensor, characterized in that: The preparation method comprises: Preparing a first flexible base (140) having a groove structure (141); A first flexible anti-stretching film (310) is stacked and fixed on the first surface of the first flexible base (140), and the first flexible anti-stretching film (310) is opposite to the area where the groove structure (141) is located; The second flexible base (150) is stacked and fixed on the second surface of the first flexible base (140), so that the first flexible base (140) and the second flexible base (150) are connected to form a flexible substrate (100), the second surface is opposite to the first surface, and the second flexible base (150) blocks the notch of the groove structure (141) to form a metal flow channel (130); pouring liquid metal (200) into the metal flow channel (130); Inserting a first end of a wire into the liquid metal (200), with a second end of the wire being located outside the flexible substrate (100); The conductive wire is fixedly connected to the first flexible anti-stretching film (310).

7. The preparation method according to claim 6, characterized in that: After the first flexible stretch-resistant film (310) is stacked and fixed on the first surface of the first flexible base (140), and before the second flexible base (150) is stacked and fixed on the second surface of the first flexible base (140), the preparation method further comprises: A liquid filling hole (400) is provided on the first flexible anti-stretching film (310) and the first flexible base (140), and the liquid filling hole (400) passes through the groove structure (141).

8. The preparation method according to claim 6, characterized in that: After the second flexible base (150) is stacked and fixed on the second surface of the first flexible base (140), and before the liquid metal (200) is poured into the metal flow channel (130), the preparation method further comprises: A second flexible anti-stretching film (320) is stacked and fixed on a surface of the second flexible base (150) that faces away from the first flexible base (140), and the second flexible anti-stretching film (320) is opposite to the area where the metal runner (130) is located.

9. The preparation method according to claim 8, characterized in that: The method of stacking and fixing the first flexible anti-stretching film (310) on the first surface of the first flexible base (140) comprises: Plasma-treating the first flexible anti-stretching film (310) and the first surface of the first flexible base (140), and laminating the first flexible anti-stretching film (310) on the first surface, so that the first flexible anti-stretching film (310) and the first flexible base (140) are bonded and connected; The method of stacking and fixing the second flexible base (150) on the second surface of the first flexible base (140) comprises: Plasma-treating the second surface of the second flexible base (150) and the first flexible base (140), and attaching the second flexible base (150) to the second surface, so that the second flexible base (150) and the first flexible base (140) are bonded and connected; The method of stacking and fixing a second flexible stretch-resistant film (320) on a surface of the second flexible base (150) facing away from the first flexible base (140) comprises: The surface of the second flexible base (150) facing away from the first flexible base (140) and the second flexible anti-stretching film (320) are plasma treated, and the second flexible anti-stretching film (320) is adhered to the surface of the second flexible base (150) facing away from the first flexible base (140) so that the second flexible anti-stretching film (320) is bonded to the second flexible base (150).

10. The preparation method according to claim 6, characterized in that: The method of preparing the first flexible base (140) having the groove structure (141) comprises: Coating a photoresist (620) on a silicon wafer (610); Covering the photoresist (620) with a mask (630); Exposing the photoresist (620) covered with the mask (630) to ultraviolet light (640); removing the mask (630); Using a developer to wash the photoresist (620) so as to form a photolithography structure on the silicon wafer (610); Pouring a flexible substrate prepolymer onto the silicon wafer (610) having the photolithography structure, and baking the flexible substrate prepolymer so that the flexible substrate prepolymer forms a first flexible base (140); The first flexible base (140) is peeled off from the silicon wafer (610).

11. The preparation method according to claim 6, characterized in that: The flexible substrate (100) comprises a pressure sensing area (110) and an extension area (120), wherein the extension area (120) is connected to the outer periphery of the pressure sensing area (110), and the area where the metal flow channel (130) is located forms the pressure sensing area (110).

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