A piezoresistive double-spherical flexible pressure sensor and a preparation method thereof

Abstract

The application provides a piezoresistive double-spherical flexible pressure sensor and a preparation method thereof, and relates to the technical field of flexible electronics. The flexible pressure sensor comprises at least two flexible substrate layers, a sensing material layer and a flexible electrode layer. The two flexible substrate layers are arranged at intervals. The flexible substrate layer comprises a substrate and a protrusion. The protrusion is arranged on one side of the substrate. When the flexible substrate layer is subjected to pressure, the resistance of the sensing material layer increases, so that an electrical signal is output. Due to the structural design of the double-spherical pressure sensor, two independent point pulse wave signals can be synchronously output. Through double-channel pulse wave collection, the transmission time of the pulse waves before and after the radial artery of the wrist is obtained. In combination with a monitoring distance, the propagation speed of the pulse wave can be calculated, so that reliable data sets are provided for blood pressure detection, and key technical support is provided for a wearable real-time human health monitoring system. Meanwhile, since the flexible substrate layer is made of a flexible material, the comfort of the sensor when worn is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible electronics, in particular to a piezoresistive double-spherical flexible pressure sensor and a preparation method thereof. BACKGROUND

[0002] Currently, with the rapid development of the Internet of Things, intelligent medical care and other fields, the demand for sensors is increasing. Traditional rigid sensors have limitations in comfort, adaptability and conformability to complex surfaces, so flexible pressure sensors have become a research hotspot. They maintain sensing performance while providing better user experience and a wider range of application scenarios.

[0003] Flexible sensors make real-time wearable human health monitoring possible. Pulse wave, as a key indicator of human health among human physiological parameters, is closely related to a series of cardiovascular parameters such as heart rate and blood pressure, attracting extensive attention from researchers in the field of flexible sensing. Therefore, designing a flexible pressure sensor with high sensitivity, good durability and fast response time to achieve accurate non-invasive pulse wave detection is a challenging task. SUMMARY

[0004] The present application provides a piezoresistive double-spherical flexible pressure sensor to solve the problems of low detection accuracy, poor comfort and low sensitivity of existing sensors.

[0005] The present application provides a piezoresistive double-spherical flexible pressure sensor, comprising:

[0006] At least two flexible substrate layers, the two flexible substrate layers are arranged at intervals, the flexible substrate layer comprises a substrate and a protrusion, the protrusion is arranged on one side of the substrate;

[0007] A sensing material layer is arranged on the surface of the substrate and the protrusion;

[0008] A flexible electrode layer is arranged on one side of the substrate, the flexible electrode layer is provided with two spaced conductive tin paste layers, the two conductive tin paste layers are located on both sides of the protrusion, and the two conductive tin paste layers are connected with the sensing material layers on both sides of the protrusion through conductive glue, when the flexible substrate layer is subjected to pressure, the resistance of the sensing material layer increases.

[0009] According to the piezoresistive double-spherical flexible pressure sensor provided by the present application, the piezoresistive double-spherical flexible pressure sensor further comprises:

[0010] A packaging layer is arranged on the side of the sensing material layer away from the flexible substrate layer.

[0011] The convex is a semi-ellipsoid.

[0012] The connection between the substrate and the convex is connected through a round corner.

[0013] The material of the flexible substrate layer and the material of the packaging layer are both Ecoflex, and the material of the sensing material layer is water-based graphene slurry.

[0014] The flexible electrode layer is provided with two through holes, and the distance between the two through holes is equal to the distance between two convexes in the same group.

[0015] The application further provides a preparation method of the piezoresistive double-spherical flexible pressure sensor.

[0016] A plurality of flexible substrate layers connected in sequence are prepared by using a substrate mold and taking Ecoflex as a substrate material, and the outer periphery of the plurality of flexible substrate layers is formed with a side wall.

[0017] A graphene-isopropyl alcohol dispersion solution is dropped and coated on the surface of the substrate and the convex, and is dried to form a sensing material layer on the surface of the substrate and the convex.

[0018] The plurality of flexible substrate layers connected in sequence are cut into two flexible substrate layers as a group.

[0019] A flexible electrode layer is arranged on one side of the substrate, a conductive tin paste layer of the flexible electrode layer is connected to the flexible electrode layer on both sides of the convex by using conductive glue, and is dried and solidified.

[0020] The preparation method of the piezoresistive double-spherical flexible pressure sensor further comprises the following steps after the step of connecting the conductive tin paste layer of the flexible electrode layer to the sensing material layer on both sides of the convex by using conductive glue, and drying and solidifying.

[0021] Ecoflex is suspended and coated on the side of the sensing material layer away from the flexible substrate layer, and is naturally air-dried to form a packaging layer.

[0022] The height of the side wall is greater than the height of the convex.

[0023] The preparation method of the piezoresistive double-spherical flexible pressure sensor provided by the application has the advantages that the mass ratio of the aqueous graphene slurry to the isopropyl alcohol solution in the graphene-isopropyl alcohol dispersion solution is 1:10.

[0024] The piezoresistive double-spherical flexible pressure sensor provided by the application has the advantages that when the flexible substrate layer is subjected to pressure, the resistance of the sensing material layer increases, so that an electrical signal is output; due to the structural design of the double-spherical pressure sensor, two independent point pulse wave signals can be synchronously output, the transmission time of the wrist radial artery pulse waves before and after is obtained through double-channel pulse wave collection, and the propagation speed of the pulse wave can be calculated by combining the monitoring distance, so that reliable data sets are provided for blood pressure detection, and key technical support is provided for a wearable real-time human health monitoring system; meanwhile, the flexible substrate layer is made of a flexible material, so that the comfort of the sensor when worn is improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort.

[0026] Figure 1 is a flowchart of the preparation method of the piezoresistive double-spherical flexible pressure sensor provided by the application.

[0027] Figure 2 is a structural schematic diagram of the piezoresistive double-spherical flexible pressure sensor provided by the application.

[0028] Figure 3 is a structural schematic diagram of the substrate mold provided by the application.

[0029] Figure 4 is a structural schematic diagram of the flexible electrode layer used for testing the performance of the single-spherical flexible pressure sensor provided by the application.

[0030] Figure 5 is a structural schematic diagram of the flexible electrode layer used for testing the performance of the double-spherical flexible pressure sensor provided by the application.

[0031] Figure 6 is a sensitivity curve diagram for performance analysis of the single-spherical flexible pressure sensor provided by the application.

[0032] Figure 7 is a 1000-cycle curve diagram for performance analysis of the single-spherical flexible pressure sensor provided by the application.

[0033] Figure 8It is a radial artery pulse detection graph detected by a single ball flexible pressure sensor.

[0034] Figure 9 It is an amplified waveform graph of the radial artery pulse.

[0035] Figure 10 It is a fingertip artery pulse detection graph detected by a single ball flexible pressure sensor.

[0036] Figure 11 It is a neck artery pulse detection graph detected by a single ball flexible pressure sensor.

[0037] Figure 12 It is a dual-channel pulse electrical signal graph output by the piezoresistive dual-ball flexible pressure sensor provided by the application.

[0038] Figure 13 It is an amplified schematic diagram of the dual-channel pulse electrical signal.

[0039] Reference signs:

[0040] 100, flexible substrate layer; 110, substrate; 120, protrusion; 200, sensing material layer; 300, flexible electrode layer; 310, conductive tin paste layer; 400, encapsulation layer; 500, conductive glue; 600, substrate mold; 700, sidewall. DETAILED DESCRIPTION

[0041] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below in combination with the drawings in the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0043] In the description of the embodiments of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "connected", "connected to", "connection" should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0044] In the embodiments of the present application, unless otherwise specifically defined and limited, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be "under", "below" and "under" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0045] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0046] The following will be described in combination with Figures 1-5 The structure schematic diagram of the piezoresistive double-spherical flexible pressure sensor of the present application is described.

[0047] As Figure 1 and Figure 2As shown, the piezoresistive double-spherical flexible pressure sensor comprises at least two flexible substrate layers 100, a sensing material layer 200 and a flexible electrode layer 300, the two flexible substrate layers 100 are arranged at intervals, the flexible substrate layer 100 comprises a substrate 110 and a protrusion 120, the protrusion 120 is arranged on one side of the substrate 110, and the sensing material layer 200 is arranged on the surface of the substrate 110 and the protrusion 120. The flexible electrode layer 300 is arranged on one side of the substrate 110, the flexible electrode layer 300 is provided with two spaced-apart conductive tin paste layers 310, the two conductive tin paste layers 310 are located on both sides of the protrusion 120, and the two conductive tin paste layers 310 are connected with the sensing material layer 200 on both sides of the protrusion 120 through conductive glue 500. When the flexible substrate layer 100 is subjected to pressure, the resistance of the sensing material layer 200 increases.

[0048] The piezoresistive double-spherical flexible pressure sensor provided by the application can output electrical signals by increasing the resistance of the sensing material layer 200 when the flexible substrate layer 100 is subjected to pressure. Due to the structural design of the double-spherical pressure sensor, two independent point pulse wave signals can be output synchronously, the transmission time (PTT) of the wrist radial artery pulse wave before and after the pulse wave is collected through the double-channel pulse wave, and the propagation speed (PWV) of the pulse wave can be calculated by combining the monitoring distance (D), so as to provide reliable data set for blood pressure detection and provide key technical support for wearable real-time human health monitoring system. Meanwhile, the flexible substrate layer 100 is made of flexible material, so that the comfort of the sensor when worn is improved.

[0049] In an embodiment of the application, as shown in Figure 2 The piezoresistive double-spherical flexible pressure sensor further comprises an encapsulation layer 400 arranged on the side of the sensing material layer 200 away from the flexible substrate layer 100. The material of the flexible substrate layer 100 and the material of the encapsulation layer 400 are both Ecoflex. Since the material of the flexible substrate layer 100 and the material of the encapsulation layer 400 are of the same type, the Young's modulus of the material of the flexible substrate layer 100 and the material of the encapsulation layer 400 is the same, so that the modulus mismatch under pressure can be prevented. Meanwhile, the Ecoflex flexible material with good elastic performance makes the sensor comfortable to wear and applicable to wearable monitoring in different scenes.

[0050] In an embodiment of the present application, the protrusion 120 is a semi-ellipsoid, i.e. the protrusion 120 is a part of an ellipsoid. The purpose of using the ellipsoid structure design is that compared with the semi-sphere structure, the flexible substrate layer 100 deforms more obviously when subjected to pressure, which helps to improve the sensitivity. Of course, the shape of the protrusion 120 is not limited thereto, and can also be a semi-sphere or other shapes. The two flexible protrusions 120 form a flexible double-sphere structure substrate, which is prepared by using a template method. In the present embodiment, the substrate 110 is a rectangular plate, and of course, can also be a regular polygon or other shapes. The protrusion 120 is arranged on one side of the substrate 110 and is integrally formed with the substrate 110.

[0051] In an embodiment of the present application, the connection between the substrate 110 and the protrusion 120 is connected by a round corner, i.e. Figure 2 the connection between the bottom of the protrusion 120 and the upper surface of the substrate 110 is connected by a round corner. By connecting the connection between the substrate 110 and the protrusion 120 by a round corner, the stress concentration at the connection can be effectively reduced, thereby improving the mechanical strength and service life of the structure and preventing damage under long-term use or repeated pressure.

[0052] In an embodiment of the present application, as shown in Figure 5 the flexible electrode layer 300 is an FPCB (flexible circuit board), and of course, the specific type of the flexible electrode layer 300 is not limited thereto, and can also be other types of flexible electrode layer 300. The FPCB is in a Y-shaped structure, and the two branches of the Y-shaped structure are square plate frame layers. The plate frame layers are provided with a conductive tin paste layer 310, and are led out to the tail of the flexible electrode layer 300 through the linear conductive tin paste layer 310. The FPCB can lead out the electrical signals of the double-path sensor, and the leading-out part and the connection part of the sensor layer are designed with a rounded corner, which aims to reduce the stress concentration during long-term use and improve the mechanical strength. The flexible electrode layer 300 is provided with two through holes, which are located on the two branches of the Y-shaped structure, and the distance between the two through holes is equal to the distance between the two protrusions 120 of the same group, i.e. the distance between the two through holes and the distance between the two protrusions 120 of the same group are both D.

[0053] In an embodiment of the present application, the piezoresistive double-sphere flexible pressure sensor of the present application can stably monitor the radial artery of the human wrist, the fingertip artery and the carotid artery, etc. Among them, the test of the radial artery of the human wrist is more stable, the waveform effect is best, and the wearing comfort is high. Since the distance between the two protrusions 120 is known as D, by measuring the transmission time (PTT) of the pulse wave before and after the radial artery of the wrist, combined with the monitoring distance D, the propagation velocity PWV of the pulse wave can be calculated as D / PTT, thereby providing reliable data support for the prediction of blood pressure value.

[0054] In an embodiment of the present application, the material of the sensing material layer 200 is aqueous graphene paste, and of course, the material of the sensing material layer 200 is not limited to this, and other materials can also be used. Graphene is a sheet-shaped stacked material structure, when the protrusion 120 coated with graphene is subjected to pressure, on the one hand, the sheet-shaped structure will be stacked and staggered; on the other hand, the pressure will also cause the protrusion 120 to deform, thereby causing the graphene material of the sensing material layer 200 to crack, both of which will cause the resistance of the piezoresistive double-spherical flexible pressure sensor to increase.

[0055] The present application also provides a preparation method of a piezoresistive double-spherical flexible pressure sensor, the preparation method is used for preparing the piezoresistive double-spherical flexible pressure sensor described in any one of the above embodiments, and comprises the following steps:

[0056] In step S100, a plurality of sequentially connected flexible substrate layers 100 are prepared by using a substrate mold 600 with Ecoflex as the substrate material, and a side wall 700 is formed around the periphery of the plurality of flexible substrate layers 100.

[0057] It should be noted that the substrate mold 600 is processed by 3D printing, and the double-spherical flexible substrate is obtained by using the reverse mold method when the flexible substrate layer is prepared. The plurality of sequentially connected flexible substrate layers 100 form a 1×n (n is an even number) ellipsoidal structure array, and a batch of n / 2 groups of flexible substrate layers 100 can be prepared. The side wall 700 is provided around the ellipsoidal array, and the height of the side wall 700 is greater than the height of the protrusion. When the sensing material solution is coated, the height of the side wall 700 is greater than the height of the protrusion, which can ensure that the sensing material solution on the six ellipsoids reaches a uniform level, thereby making the coating uniform.

[0058] It should be further noted that, as shown in Figure 3 In the present embodiment, the design layout of the substrate mold 600 is a 1×6 ellipsoidal groove structure array, wherein 2 ellipsoidal grooves form a group, and a batch of 3 groups of flexible substrate layers 100 can be prepared. The distance D between the two ellipsoidal grooves is 20 mm, the lengths of the ellipsoidal grooves on the x, y and z semi-axes are 3.65 mm, 3.65 mm and 5.5 mm, the base of the substrate mold 600 is a rectangular box with a thickness of 2 mm, and the substrate mold 600 is also specially designed with a side wall 700 surrounding the six ellipsoids, and the height of the side wall 700 is 8 mm.

[0059] Further, before performing step S100, the mold surface needs to be sprayed with Smooth-on Release200 silicone aerosol release agent for pre-release treatment before the experiment. The material of the flexible substrate layer 100 is selected from Smooth-On Ecoflex™00-30AF Anti Funga, and the mass ratio of A glue to B glue is 1:1 during configuration, and the substrate material is poured into the substrate mold 600, and the substrate material is placed for 5h for curing and forming, and then the substrate is released.

[0060] Step S200, graphene-isopropanol dispersion solution is dropped on the surface of the substrate 110 and the protrusion 120 and is dried to form a sensing material layer 200 on the surface of the substrate 110 and the protrusion 120.

[0061] It should be noted here that the sensing material layer 200 is selected from water-based graphene paste 5%, in order to ensure uniform coating, the water-based graphene paste needs to be dissolved in isopropanol solution and shaken and dispersed uniformly. The mass ratio of water-based graphene paste to isopropanol solution in the graphene-isopropanol dispersion solution is 1:10. After the graphene-isopropanol dispersion solution is prepared, the graphene-isopropanol dispersion solution is dropped on the Ecoflex substrate material, immersed to the top of the six ellipsoids, and placed in an 80°C oven for 3h to completely volatilize the isopropanol and water.

[0062] Step S300, the plurality of sequentially connected flexible substrate layers 100 are cut into two flexible substrate layers 100 as a group.

[0063] It should be noted here that in this embodiment, the six sequentially connected flexible substrate layers 100 are cut into two flexible substrate layers 100 as a group, so that three groups of flexible substrate layers 100 are obtained. Of course, the number of flexible substrate layers 100 is not limited to this, and is determined according to actual needs.

[0064] Step S400, the flexible electrode layer 300 is arranged on one side of the substrate 110, the conductive tin paste layer 310 of the flexible electrode layer 300 is connected to the sensing material layer 200 on both sides of the protrusion 120 by using the conductive adhesive 500, and is dried and cured.

[0065] It should be noted here that when the flexible electrode layer 300 is connected to the double-sphere substrate, the conductive tin paste layer 310 of the flexible electrode layer 300 is connected to the sensing material layer 200 on both sides of the protrusion 120 by using the flexible conductive silver adhesive, the mass ratio of the curing agent to the colloid in the conductive silver adhesive is 1:10, and the conductive silver adhesive is uniformly stirred. After uniform stirring, the conductive silver adhesive is coated on both sides of the protrusion 120, and then the flexible electrode layer 300 is covered, and is placed in a 60°C oven for 1h to completely cure the conductive silver adhesive.

[0066] In one embodiment of the present application, after the step of connecting the conductive tin paste layer 310 of the flexible electrode layer 300 with the sensing material layer 200 on both sides of the protrusions 120 by using the conductive glue 500 and drying and curing, the preparation method further comprises:

[0067] Step S500, the Ecoflex is suspended on the side of the sensing material layer 200 away from the flexible substrate layer 100 and is naturally air-dried to form the encapsulation layer 400.

[0068] It should be noted that after the flexible electrode layer 300 is fixed, the connection between the two protrusions 120 is cut off to make the two protrusions 120 electrically insulated, and Smooth-On Ecoflex™ 00-30AF AntiFunga is used for encapsulation, and the mass ratio of A glue to B glue is 1:1 and is stirred uniformly; then the double-ball sensor device is suspended with Ecoflex for encapsulation, and is air-dried at room temperature for 5h.

[0069] As shown in Figure 4 When the piezoresistive double-ball flexible pressure sensor of the present application is tested as a single-ball device, the FPC 6PIN soft wire adapter plate is used to connect the lead electrodes and is connected to the Keithley DMM6500 6.5-bit digital multimeter for testing.

[0070] In order to understand the performance of the piezoresistive double-ball flexible pressure sensor, the sensitivity of the piezoresistive double-ball flexible pressure sensor needs to be tested first, as shown in Figure 6 As shown in

[0071] The cycle stability of the piezoresistive double-ball flexible pressure sensor is tested, as shown in Figure 7 When testing, the tensile machine provides a comparable pressure (~1kPa) and a cycle frequency (1 second / cycle) for simulating the pulse wave test, and the change curve of the resistance change rate ΔR / R0 of the piezoresistive double-ball flexible pressure sensor in 1000 cycle tests can be seen. From the results, it can be seen that the piezoresistive double-ball flexible pressure sensor of the present application has good cycle stability, fatigue resistance and durability.

[0072] The piezoresistive double-ball flexible pressure sensor of the present application can be applied to different scenes and can simulate the pulse wave test on different parts of the human body. The following describes several application scenes of the piezoresistive double-ball flexible pressure sensor.

[0073] Scenario one, the flexible double ball flexible pressure sensor is placed on the human wrist, the relative resistance change of the radial artery of the human body is tested, and the test result is as shown in Figure 8 It can be seen from the figure that the resistance change rate presents a stable periodic change with the pulse frequency. The amplified waveform of the radial artery is as shown in Figure 9 The output electrical data is a typical pulse wave type, and obvious ascending branch, descending branch, main wave (P), tidal wave (T) and heavy thin wave (D) can be seen.

[0074] Scenario two, the piezoresistive double ball flexible pressure sensor of the application is placed on the fingertips of the human body, the relative resistance change of the fingertips of the human body is tested, and only the electrical signal output of the single ball of the device is detected. The test result is as shown in Figure 10 It can be seen from the figure that the resistance change rate presents a stable periodic change with the pulse frequency. When the piezoresistive double ball flexible pressure sensor of the application is applied to test the fingertips of the human body, a larger pre-pressure needs to be applied due to the weak fingertips of the human body.

[0075] Scenario three, the piezoresistive double ball flexible pressure sensor of the application is placed on the neck of the human body, the relative resistance change of the carotid artery of the human body is tested, and only the electrical signal output of the single ball of the device is detected. The test result is as shown in Figure 11 It can be seen from the figure that the resistance change rate presents a stable periodic change with the pulse frequency.

[0076] As a preferred, the piezoresistive double ball flexible pressure sensor tests the radial artery of the human wrist, which is relatively stable and has the best waveform effect.

[0077] Scenario four, the piezoresistive double ball flexible pressure sensor of the application is placed on the radial artery of the human wrist, combined with the acquisition circuit board, and two-way pulse signals are collected simultaneously, the sampling frequency is 1 kHz, and two-way electrical signals are output.

[0078] The piezoresistive double ball flexible pressure sensor of the application can stably collect two-way pulse signals, and the test result is as shown in Figure 12 It can be seen from the figure that the two-way output electrical signals present a stable periodic change with the pulse frequency.

[0079] The two-way pulse signals collected by the piezoresistive double ball flexible pressure sensor of the application have a transmission time (PTT), as shown in Figure 13 The transmission time (PTT) of the two-way pulse wave waveforms is about 5 ms, and combined with the monitoring distance D=20 mm, the propagation speed PWV of the pulse wave can be calculated to be about 4 m / s, and combined with a large number of collected data sets, thereby providing reliable data support for the prediction of blood pressure values.

[0080] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A piezoresistive double-spherical flexible pressure sensor, characterized in that, include: At least two flexible substrate layers (100) are arranged at intervals, each flexible substrate layer (100) including a substrate (110) and a protrusion (120) disposed on one side of the substrate (110); A sensing material layer (200) is disposed on the surface of the substrate (110) and the protrusion (120); A flexible electrode layer (300) is disposed on one side of the substrate (110). The flexible electrode layer (300) is provided with two spaced conductive solder paste layers (310). The two conductive solder paste layers (310) are located on both sides of the protrusion (120). The two conductive solder paste layers (310) are connected to the sensing material layers (200) on both sides of the protrusion (120) by conductive adhesive (500). When the flexible substrate layer (100) is subjected to pressure, the resistance of the sensing material layer (200) increases.

2. The piezoresistive double-spherical flexible pressure sensor according to claim 1, characterized in that, The piezoresistive dual-spherical flexible pressure sensor also includes: An encapsulation layer (400) is disposed on the side of the sensing material layer (200) opposite to the flexible substrate layer (100).

3. The piezoresistive dual-spherical flexible pressure sensor according to claim 2, characterized in that, The protrusion (120) is a semi-ellipsoid.

4. The piezoresistive dual-spherical flexible pressure sensor according to claim 2, characterized in that, The connection between the substrate (110) and the protrusion (120) is made by rounded corners.

5. The piezoresistive double-spherical flexible pressure sensor according to any one of claims 2 to 4, characterized in that, The flexible substrate layer (100) and the encapsulation layer (400) are both made of Ecoflex, and the sensing material layer (200) is made of aqueous graphene slurry.

6. The piezoresistive dual-spherical flexible pressure sensor according to any one of claims 1 to 4, characterized in that, The flexible electrode layer (300) is provided with two through holes, and the distance between the two through holes is equal to the distance between the two protrusions (120) in the same group.

7. A method for fabricating a piezoresistive dual-spherical flexible pressure sensor, the method being used to fabricate the piezoresistive dual-spherical flexible pressure sensor according to any one of claims 1 to 6, characterized in that, include: Using a substrate mold (600) with Ecoflex as the substrate material, a plurality of flexible substrate layers (100) are prepared in sequence, and sidewalls (700) are formed on the outer periphery of the plurality of flexible substrate layers (100). A graphene-isopropanol dispersion solution is drop-coated onto the surface of the substrate (110) and the protrusion (120) and then dried to form a sensing material layer (200) on the surface of the substrate (110) and the protrusion (120). The multiple sequentially connected flexible substrate layers (100) are cut into two flexible substrate layers (100) as a group; A flexible electrode layer (300) is disposed on one side of the substrate (110), and the conductive solder paste layer (310) of the flexible electrode layer (300) is connected to the sensing material layer (200) on both sides of the protrusion (120) using conductive adhesive (500), and then dried and cured.

8. The method for fabricating a piezoresistive dual-spherical flexible pressure sensor according to claim 7, characterized in that, After the steps of connecting the conductive solder paste layer (310) of the flexible electrode layer (300) to the flexible electrode layers (300) on both sides of the protrusion (120) using conductive adhesive (500) and then drying and curing, the preparation method further includes: Ecoflex is suspended on the side of the sensing material layer (200) away from the flexible substrate layer (100) and allowed to air dry to form an encapsulation layer (400).

9. The method for fabricating a piezoresistive dual-spherical flexible pressure sensor according to claim 8, characterized in that, The height of the sidewall (700) is greater than the height of the protrusion (120).

10. The method for fabricating a piezoresistive dual-spherical flexible pressure sensor according to claim 8, characterized in that, The mass ratio of aqueous graphene slurry to isopropanol solution in the graphene-isopropanol dispersion is 1:10.

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