Resistance type pressure sensor and preparation method thereof

Abstract

The invention provides a resistive pressure sensor and a preparation method thereof, and belongs to the technical field of intelligent pressure monitoring. The resistive pressure sensor comprises a sensor main body and a packaging layer. The sensor main body comprises a first flexible substrate, a second flexible substrate, a flexible conductive layer and an electrode assembly. The first flexible substrate is provided with a plurality of first protrusions distributed in an array mode. The second flexible substrate is provided with a plurality of second protrusions distributed in an array mode, and the second protrusions and the first protrusions are distributed in a staggered mode. The flexible conducting layer is located between the first flexible substrate and the second flexible substrate, the flexible conducting layer comprises a flexible substrate and a conducting layer which are distributed in a stacked mode, the flexible substrate makes contact with the first protrusions, and the conducting layer makes contact with the second protrusions; the electrode assembly comprises two electrodes which are distributed at an interval, and the two electrodes are electrically connected with the conductive layer respectively; the packaging layer is located on the circumferential side wall of the sensor body. The resistive pressure sensor has the advantage of being large in pressure measurement range.

Description

Technical Field

[0001] This application relates to the technical field of intelligent pressure monitoring. Specifically, it relates to a resistive pressure sensor and a preparation method thereof. Background Technique

[0002] A pressure sensor is a flexible electronic device that can convert external pressure into an electrical signal, with the properties of being bendable and stretchable. Its working principle mainly depends on the physical property changes of the sensitive material, and it is usually divided into resistive (piezoresistive), capacitive, piezoelectric, etc. Currently, pressure sensors are widely used in the field of medical health. For example, using flexible electronic devices to continuously monitor the minute pressure changes caused by blood vessel pulsation can achieve non-invasive cardiovascular monitoring. Among them, how to improve the test sensitivity of the pressure sensor is one of the important indicators to judge its performance.

[0003] At present, in order to effectively improve the test sensitivity of the pressure sensor, bionic microstructure design is a commonly used technical means. For example, designing bionic fingerprint or microcolumn array structures to improve the test sensitivity. However, for the pressure sensor prepared by this improvement method, especially for the resistive pressure sensor, there is a problem that the structure is prone to collapse when used under high pressure, which leads to a smaller pressure test range. Summary of the Invention

[0004] The purpose of this application is to provide a resistive pressure sensor and a preparation method thereof. The resistive pressure sensor still has high structural stability when used under high pressure, and thus has the advantage of a large pressure measurement range.

[0005] The embodiments of this application are implemented as follows:

[0006] In a first aspect, an embodiment of this application provides a resistive pressure sensor, including a sensor main body and a packaging layer. The sensor main body includes a first flexible substrate, a second flexible substrate, a flexible conductive layer, and an electrode assembly; one side of the first flexible substrate has a plurality of first protrusions distributed in an array; the second flexible substrate is distributed opposite to the first flexible substrate, and one side of the second flexible substrate close to the first flexible substrate has a plurality of second protrusions distributed in an array, and the plurality of second protrusions and the plurality of first protrusions are staggered; the flexible conductive layer is located between the first flexible substrate and the second flexible substrate, and the flexible conductive layer includes a flexible substrate and a conductive layer distributed in a stacked manner. The flexible substrate is in contact with the first protrusions, and the conductive layer is in contact with the second protrusions; the electrode assembly includes two electrodes distributed at intervals, and the two electrodes are respectively electrically connected to the conductive layer; the packaging layer is located on the circumferential side wall of the sensor main body.

[0007] In the prior art, a traditional resistive pressure sensor generally has two upper and lower parts that can conduct electricity respectively. The upper and lower parts have array units that can form an interlocking structure and each has an electrode. When subjected to a large external pressure, the resistive pressure sensor with this structure is prone to the collapse of the array structure due to the excessive depth of mutual insertion of the two electrodes. Moreover, after the two electrodes are in full contact, it is difficult for the contact area of the two electrodes to further increase with the increase of the external pressure, resulting in the problem of a small pressure test range. In this application, by designing a resistive pressure sensor with a "sandwich structure", specifically, a first flexible substrate with a first protrusion and a second flexible substrate with a second protrusion cooperate with each other and act as a framework for transmitting the external pressure to endow the resistive pressure sensor with relatively excellent detection sensitivity. At the same time, a flexible conductive layer is additionally provided between the first flexible substrate and the second flexible substrate. Among them, the flexible substrate in the flexible conductive layer contacts the first protrusion, and the conductive layer contacts the second protrusion. When the resistive pressure sensor is subjected to an external pressure, the first protrusion and the second protrusion can be inserted into the flexible conductive layer to cause the deformation of the flexible conductive layer, thereby changing the resistance of the flexible conductive layer (so as to convert the pressure signal into an electrical signal). At the same time, when the external pressure is large, the setting of the flexible conductive layer can limit the mutual insertion depth of the first protrusion and the second protrusion, reducing the risk of the collapse of its structure, so that the resistive pressure sensor still has high structural stability under high pressure, and thus the resistive pressure sensor has the advantage of a large pressure test range.

[0008] In some alternative embodiments, the thickness of the flexible substrate in the flexible conductive layer is 17 - 40 μm; optionally, the content of the conductive material in the conductive layer is 1 - 5 mg / cm 2 .

[0009] In the above technical solution, the thickness of the flexible substrate in the flexible conductive layer is limited within the above range to provide a more appropriate thickness, which can better limit the mutual insertion depth of the first protrusion and the second protrusion, thereby more effectively maintaining the structural stability of the resistive pressure sensor when used under high pressure. At the same time, it can also enable the flexible substrate and the conductive layer on the flexible substrate to have appropriate deformation capabilities, so as to timely and sensitively convert the received external pressure into the corresponding resistance value, which helps to improve the detection sensitivity. Further, the content of the conductive material in the conductive layer is limited within the above range to make the conductive layer have relatively excellent electrical conductivity, which also helps to improve the detection sensitivity.

[0010] In some alternative embodiments, the hardness of the first flexible substrate and the second flexible substrate is greater than the hardness of the flexible substrate.

[0011] In the above technical solution, the first flexible substrate and the second flexible substrate are set to have a hardness greater than that of the flexible base, so that when the first protrusion and the second protrusion are subjected to a large external pressure, they are not easily deformed and bent by themselves and can be more easily inserted into the flexible conductive layer, thereby better maintaining the structural stability of the resistive pressure sensor when used under high pressure.

[0012] In some alternative embodiments, the shapes and sizes of the plurality of first protrusions and the plurality of second protrusions are the same; optionally, the first protrusion is a cylinder, and the diameter of the first protrusion is 10-100 μm; optionally, the distance between any two adjacent first protrusions and the distance between any two adjacent second protrusions are both 10-100 μm; optionally, the height of the first protrusion is 20-200 μm.

[0013] In the above technical solution, setting the plurality of first protrusions and the plurality of second protrusions to have the same shape and size has the advantages of a relatively regular overall structure and being convenient for manufacturing; in addition, setting the protrusions as cylinders and limiting the diameter, the distance between adjacent protrusions, and the height within the above ranges can provide a larger number of protrusions, thereby increasing the number of contact points between the protrusions and the conductive layer, which helps to improve the detection sensitivity.

[0014] In some alternative embodiments, the two electrodes are respectively electrically connected to the conductive layer through a conductive transition layer, and the content of the conductive material in the conductive transition layer is greater than the content of the conductive material in the conductive layer; optionally, the conductive material in the conductive layer is selected from at least one of silver, copper, nickel, and platinum; optionally, the conductive material in the conductive transition layer is selected from at least one of silver and gold.

[0015] In the above technical solution, the electrical connection between the electrode and the conductive layer is realized by setting a conductive transition layer. Among them, the content of the conductive material in the conductive transition layer is greater than the content of the conductive material in the conductive layer, which helps to improve the electrical conductivity between the electrode and the conductive layer and also helps to improve the detection sensitivity. Further, there are many alternative embodiments for the conductive materials in the conductive layer and the conductive transition layer, which facilitates the popularization and application of the technical solution provided by the embodiments of the present application.

[0016] In some alternative embodiments, the materials of the first flexible substrate and the second flexible substrate are the same; optionally, the material of the first flexible substrate is selected from at least one of polydimethylsiloxane, polyimide, and hydrogel.

[0017] In the above technical solution, setting the first flexible substrate and the second flexible substrate to have the same material has the advantage of being convenient for manufacturing; further, selecting the above types of materials for the first flexible substrate has the advantage of better flexibility.

[0018] In some alternative embodiments, the encapsulation layer is located at a portion of the circumferential sidewall of the sensor body.

[0019] In the above technical solution, the encapsulation layer is provided only at a portion of the circumferential sidewall of the sensor body, so that the interior of the sensor body is always in communication with the external environment, which helps the first protrusion and the second protrusion to always maintain an interleaved distribution form during the detection process.

[0020] In some alternative embodiments, the second flexible substrate includes an array unit in the middle and an edge region surrounding the array unit. The array unit includes a plurality of second protrusions distributed in an array, and the electrode assembly is located in the region corresponding to the conductive layer and the edge region.

[0021] In the above technical solution, the second flexible substrate includes an array unit in the middle and an edge region surrounding the array unit, and the electrode assembly is arranged in the region corresponding to the conductive layer and the edge region, so that the pressure transmission region and the electrical signal derivation region are relatively independent, so that each region can better perform its respective functions.

[0022] In a second aspect, an embodiment of the present application provides a method for manufacturing a resistive pressure sensor as provided in the embodiment of the first aspect, including the following steps:

[0023] A first flexible substrate having first protrusions and a second flexible substrate having second protrusions are prepared by using a template transfer technique; the raw material of the flexible substrate is applied to a planar substrate and cured to form a flexible substrate on the planar substrate; then the raw material of the conductive layer is applied to the flexible substrate and cured to form a conductive layer on the surface of the flexible substrate; then the planar substrate is removed to obtain a flexible conductive layer; two electrodes are laid at intervals on the surface of the conductive layer in the flexible conductive layer; the first flexible substrate, the flexible conductive layer with electrodes laid thereon, and the second flexible substrate are stacked and assembled in sequence, so that a plurality of first protrusions on the first flexible substrate and a plurality of second protrusions on the second flexible substrate are all interleaved, and the flexible substrate contacts the first protrusions and the conductive layer contacts the second protrusions to obtain a sensor body; the raw material of the encapsulation layer is applied to the circumferential sidewall of the sensor body and cured to form an encapsulation layer on the circumferential sidewall of the sensor body, so as to obtain a resistive pressure sensor.

[0024] In the above technical solution, by preparing according to the above process, a resistive pressure sensor as provided in the embodiment of the first aspect can be prepared, which still has high structural stability when used under high-pressure conditions, and thus has the advantage of a large test range.

[0025] In some alternative embodiments, in the step of applying the raw material of the conductive layer to the flexible substrate and curing it, the raw material of the conductive layer is applied to the flexible substrate by spraying; or / and, the material of the planar substrate is selected from at least one of polyimide, polycarbonate, and polyethylene terephthalate.

[0026] In the above technical solution, preparing the conductive layer on the flexible substrate by spraying can further improve the reproducibility of the test results of the resistive pressure sensor; further, selecting the above types of materials for the planar substrate has the advantage of facilitating the peeling of the flexible conductive layer from the planar substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is a schematic structural diagram of the first resistive pressure sensor provided by the embodiment of the present application after being disassembled;

[0029] Figure 2 It is a schematic structural diagram of the first resistive pressure sensor provided by the embodiment of the present application after being assembled;

[0030] Figure 3 It is a schematic structural diagram of the second resistive pressure sensor provided by the embodiment of the present application after being assembled;

[0031] Figure 4 It is a process flow diagram of a preparation method of a resistive pressure sensor provided by the embodiment of the present application;

[0032] Figure 5 It is an electron micrograph of the sensor body prepared in Example 1 of the present application;

[0033] Figure 6 It is a curve of the resistance change rate of the resistive pressure sensor prepared in Example 1 of the present application under different pressures;

[0034] Figure 7 It is a curve of the resistance change rate of the resistive pressure sensor prepared in Example 2 of the present application under different pressures;

[0035] Figure 8 It is a curve of the resistance change rate of the resistive pressure sensor prepared in Example 1 of the present application during the recycling process;

[0036] Figure 9It is the curve of the resistance change rate of the resistive pressure sensor prepared in Embodiment 2 of the present application during the recycling process;

[0037] Figure 10 It is the resistance curve of the resistive pressure sensor prepared in Embodiment 1 of the present application during the pulse test.

[0038] Icon: 10 - resistive pressure sensor; 100 - sensor body; 110 - first flexible substrate; 111 - first protrusion; 120 - second flexible substrate; 121 - second protrusion; 130 - flexible conductive layer; 131 - flexible substrate; 132 - conductive layer; 140 - electrode assembly; 141 - electrode; 150 - conductive transition layer. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0041] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0042] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the present application is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0043] In the description of the present application, it should also be noted that, unless otherwise clearly specified and defined, the terms "arrangement", "installation", and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0044] In the prior art, a traditional resistive pressure sensor usually has two upper and lower parts that can conduct electricity respectively. The upper and lower parts have array units capable of forming an interlocking structure and each has an electrode. When subjected to a large external pressure, the resistive pressure sensor with this structure is prone to collapse of the array structure due to the excessive depth of mutual insertion of the two electrodes. Moreover, after the two electrodes are in full contact, it is difficult for the contact area of the two electrodes to further increase with the increase of the external pressure, resulting in the problem of a relatively small measurement range.

[0045] Based on this, the inventor has found through research that by optimizing the structure of the resistive pressure sensor, specifically, adding a flexible conductive layer between two flexible substrates to make the resistive pressure sensor have a "sandwich structure", which can limit the mutual insertion depth of the first protrusion and the second protrusion, so that the resistive pressure sensor still has high structural stability under high pressure, and thus the resistive pressure sensor has the advantage of a relatively large measurement range.

[0046] The following specifically describes a resistive pressure sensor and a preparation method thereof provided by the present application.

[0047] Refer to Figure 1 and Figure 2, in a first aspect, an embodiment of the present application provides a resistive pressure sensor 10, which includes a sensor body 100 and a packaging layer (not shown in the figure). The sensor body 100 includes a first flexible substrate 110, a second flexible substrate 120, a flexible conductive layer 130, and an electrode assembly 140; one side of the first flexible substrate 110 has a plurality of first protrusions 111 distributed in an array; the second flexible substrate 120 is distributed opposite to the first flexible substrate 110, and one side of the second flexible substrate 120 close to the first flexible substrate 110 has a plurality of second protrusions 121 distributed in an array, and the plurality of second protrusions 121 and the plurality of first protrusions 111 are alternately distributed; the flexible conductive layer 130 is located between the first flexible substrate 110 and the second flexible substrate 120, and the flexible conductive layer 130 includes a flexible substrate 131 and a conductive layer 132 distributed in a stacked manner. The flexible substrate 131 is in contact with the first protrusions 111, and the conductive layer 132 is in contact with the second protrusions 121; the electrode assembly 140 includes two electrodes 141 distributed at intervals, and the two electrodes 141 are respectively electrically connected to the conductive layer 132; the packaging layer is located on the circumferential side wall of the sensor body 100.

[0048] In the present application, by designing a resistive pressure sensor 10 with a "sandwich structure", specifically, the first flexible substrate 110 with the first protrusions 111 and the second flexible substrate 120 with the second protrusions 121 cooperate with each other and can act as a framework for transmitting external pressure to endow the resistive pressure sensor 10 with relatively excellent detection sensitivity; at the same time, a flexible conductive layer 130 is additionally provided between the first flexible substrate 110 and the second flexible substrate 120. Among them, the flexible substrate 131 in the flexible conductive layer 130 is in contact with the first protrusions 111, and the conductive layer 132 is in contact with the second protrusions 121. When the resistive pressure sensor 10 is subjected to external pressure, the first protrusions 111 and the second protrusions 121 can be inserted into the flexible conductive layer 130 to cause deformation of the flexible conductive layer 130, thereby changing the resistance of the flexible conductive layer 130 (so as to convert the pressure signal into an electrical signal); at the same time, when the external pressure is large, the setting of the flexible conductive layer 130 can limit the mutual insertion depth of the first protrusions 111 and the second protrusions 121, reducing the risk of the collapse of its structure, so that the resistive pressure sensor 10 still has high structural stability under high pressure, and further enabling the resistive pressure sensor 10 to have the advantages of a larger test range and better reproducibility of test results.

[0049] It should be noted that when the external pressure is extremely high, the first protrusion 111 will cause the flexible conductive layer 130 to deform and insert into the groove between the opposing second protrusions 121 together with the flexible conductive layer 130. However, compared with the form in the prior art where the flexible conductive layer 130 is not provided, the insertion depth will be reduced. At the same time, when the external pressure is extremely high, the second protrusion 121 will also cause the flexible conductive layer 130 to deform and insert into the groove between the opposing first protrusions 111 together with the flexible conductive layer 130. However, compared with the form in the prior art where the flexible conductive layer 130 is not provided, the insertion depth will be reduced.

[0050] It should be noted that when the external pressure is relatively low, the first protrusion 111 and the second protrusion 121 will also cause slight deformation of the flexible conductive layer 130, but the first protrusion 111 and the second protrusion 121 will not extend into the opposing grooves, and only the flexible conductive layer 130 extends into the grooves in the corresponding regions respectively.

[0051] It should be noted that the electrode assembly 140 is used for electrical connection with an external detection device, so as to form a circuit between the conductive layer 132 and the detection device, thereby detecting the resistance value of the conductive layer 132 under the action of pressure.

[0052] Refer to Figure 1 and Figure 2 , as an example, the second flexible substrate 120 includes an array unit in the middle and an edge region surrounding the array unit. The array unit includes a plurality of second protrusions 121 distributed in an array, and the electrode assembly 140 is located in the region corresponding to the conductive layer 132 and the edge region.

[0053] In this embodiment, the second flexible substrate 120 includes an array unit in the middle and an edge region surrounding the array unit, and the electrode assembly 140 is arranged in the region corresponding to the conductive layer 132 and the edge region, so that the pressure transmission region and the electrical signal output region are relatively independent, so that each region can better perform its respective functions.

[0054] It should be noted that the first flexible substrate 110 also includes an array unit in the middle and an edge region surrounding the array unit, wherein the array unit includes a plurality of first protrusions 111 distributed in an array.

[0055] As an example, the thickness of the flexible substrate 131 in the flexible conductive layer 130 is 17 - 40 μm, such as but not limited to any one of the point values of 17 μm, 20 μm, 25 μm, 30 μm, 35 μm, and 40 μm or the range values between any two of them.

[0056] In this embodiment, the thickness of the flexible substrate 131 in the flexible conductive layer 130 is limited within the above range to provide a more suitable thickness, which can preferably limit the mutual insertion depth of the first protrusion 111 and the second protrusion 121, so as to more effectively maintain the structural stability of the resistive pressure sensor 10 when used under high pressure. At the same time, it can also enable the flexible substrate 131 and the conductive layer 132 on the flexible substrate 131 to have appropriate deformation capabilities, so as to timely and sensitively convert the received external pressure into a corresponding resistance value, thereby helping to improve the detection sensitivity.

[0057] As an example, the content of the conductive material in the conductive layer 132 is 1-5 mg / cm 2 , for example but not limited to, the content is 1 mg / cm 2 , 2 mg / cm 2 , 3 mg / cm 2 , 4 mg / cm 2 and 5 mg / cm 2 any one of the point values or the range values between any two of them.

[0058] In this embodiment, the content of the conductive material in the conductive layer 132 is limited within the above range, so that the conductive layer 132 has relatively excellent conductive performance, which also helps to improve the detection sensitivity.

[0059] As an example, the hardness of the first flexible substrate 110 and the second flexible substrate 120 is greater than that of the flexible substrate 131.

[0060] In this embodiment, the first flexible substrate 110 and the second flexible substrate 120 are set to have a hardness greater than that of the flexible substrate 131, so that the first protrusion 111 and the second protrusion 121 are not easily deformed and bent by themselves when subjected to a large external pressure and can be more easily inserted into the flexible conductive layer 130, thereby better maintaining the structural stability of the resistive pressure sensor 10 when used under high pressure.

[0061] It should be noted that the shapes and sizes of the first protrusion 111 and the second protrusion 121 are not limited and can be set according to actual needs.

[0062] As an example, the shapes and sizes of the plurality of first protrusions 111 and the plurality of second protrusions 121 are the same.

[0063] In this embodiment, the plurality of first protrusions 111 and the plurality of second protrusions 121 are set to have the same shapes and sizes, which has the advantages of a relatively regular overall structure and being convenient for manufacturing.

[0064] Refer to Figure 1, as an example, the first protrusion 111 is a cylinder, and the diameter of the first protrusion 111 is 10 to 100 μm. For example, but not limited to, any one of the point values of 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, and 100 μm or the range value between any two of them.

[0065] As an example, the spacing between any two adjacent first protrusions 111 and the spacing between any two adjacent second protrusions 121 are both 10 to 100 μm. For example, but not limited to, any one of the point values of 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, and 100 μm or the range value between any two of them.

[0066] As an example, the height of the first protrusion 111 is 20 to 200 μm. For example, but not limited to, any one of the point values of 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, and 200 μm or the range value between any two of them.

[0067] In this embodiment, setting the protrusions as cylinders and limiting the diameter, the spacing between adjacent protrusions, and the height within the above ranges can provide a relatively large number of protrusions, thereby increasing the number of contact points between the protrusions and the conductive layer 132, which helps to improve the detection sensitivity.

[0068] It should be noted that since the first protrusion 111 and the second protrusion 121 are the same, the second protrusion 121 can be set with reference to the first protrusion 111.

[0069] Refer to Figure 3 , as an example, the two electrodes 141 are respectively electrically connected to the conductive layer 132 through the conductive transition layer 150, and the content of the conductive material in the conductive transition layer 150 is greater than the content of the conductive material in the conductive layer 132.

[0070] In this embodiment, the electrical connection between the electrode 141 and the conductive layer 132 is realized by setting the conductive transition layer 150. Among them, the content of the conductive material in the conductive transition layer 150 is greater than the content of the conductive material in the conductive layer 132, which helps to improve the electrical conductivity between the electrode 141 and the conductive layer 132 and also helps to improve the detection sensitivity.

[0071] In other possible embodiments, the electrode 141 can also be directly electrically connected to the conductive layer 132.

[0072] As an example, the conductive material in the conductive layer 132 is selected from at least one of silver, copper, nickel, and platinum, and / or the conductive material in the conductive transition layer 150 is selected from at least one of silver and gold.

[0073] In this embodiment, there are many possible implementation schemes for the conductive materials in the conductive layer 132 and the conductive transition layer 150, which facilitates the popularization and application of the technical solution provided by the embodiments of the present application.

[0074] It should be noted that the type of the conductive material is not limited. For example, it can be in the form of nanowires or particles. In the embodiments of the present application, the conductive material in the conductive layer 132 is in the form of nanowires, and the conductive material in the conductive transition layer 150 is in the form of particles.

[0075] As an example, the materials of the first flexible substrate 110 and the second flexible substrate 120 are the same.

[0076] In this embodiment, setting the first flexible substrate 110 and the second flexible substrate 120 to have the same material has the advantage of facilitating manufacturing.

[0077] As an example, the material of the first flexible substrate 110 is selected from at least one of polydimethylsiloxane, polyimide, and hydrogel.

[0078] In this embodiment, selecting the above types of materials for the first flexible substrate 110 has the advantage of better flexibility.

[0079] In other possible embodiments, the material of the first flexible substrate 110 can also be different from that of the second flexible substrate 120.

[0080] As an example, the material of the flexible substrate 131 is selected from at least one of polydimethylsiloxane, polyimide, and hydrogel.

[0081] As an example, the encapsulation layer is located at a part of the circumferential sidewall of the sensor body 100.

[0082] In this embodiment, the encapsulation layer is only provided at a part of the circumferential sidewall of the sensor body 100, so that the inside of the sensor body 100 is always in communication with the external environment, which helps the first protrusion 111 and the second protrusion 121 to always maintain an interleaved distribution form during the detection process.

[0083] In other possible embodiments, it can also be that the circumferential sidewall of the sensor body 100 is provided with an encapsulation layer.

[0084] It should be noted that for the structural or functional units in the resistive pressure sensor 10 that are not specifically described or limited, they can be set according to the conventional selection in the art.

[0085] As an example, the electrode 141 is a copper foil with conductive adhesive, wherein one side of the conductive adhesive is bonded to the surface of the conductive transition layer 150.

[0086] In a second aspect, an embodiment of the present application provides a method for manufacturing a resistive pressure sensor as provided in the embodiment of the first aspect, including the following steps:

[0087] A first flexible substrate having first protrusions and a second flexible substrate having second protrusions are prepared by using a template transfer technique; the raw material of the flexible substrate is applied to a planar substrate and cured to form a flexible substrate on the planar substrate; then the raw material of the conductive layer is applied to the flexible substrate and cured to form a conductive layer on the surface of the flexible substrate; then the planar substrate is removed to obtain a flexible conductive layer; two electrodes are laid at intervals on the surface of the conductive layer in the flexible conductive layer; the first flexible substrate, the flexible conductive layer after laying the electrodes, and the second flexible substrate are stacked and assembled in sequence, so that multiple first protrusions on the first flexible substrate and multiple second protrusions on the second flexible substrate are staggered, and the flexible substrate contacts the first protrusions and the conductive layer contacts the second protrusions to obtain a sensor body; the raw material of the encapsulation layer is applied to the circumferential side wall of the sensor body and cured to form an encapsulation layer on the circumferential side wall of the sensor body, obtaining a resistive pressure sensor.

[0088] In the present application, by preparing according to the above process, a resistive pressure sensor as provided in the embodiment of the first aspect can be obtained, which still has high structural stability when used under high pressure conditions, thereby enabling it to have the advantage of a large test range.

[0089] It should be noted that in the step of preparing a first flexible substrate having first protrusions and a second flexible substrate having second protrusions by using a template transfer technique, the source of the template is not limited. For example, the template can be prepared by means of 3D printing, photolithography or ICP etching.

[0090] It should be noted that the array units on the first flexible substrate and the second flexible substrate can be arranged in a relative manner (that is, the forms of the array units on the two flexible substrates are the same), or in a staggered distribution form. It should be noted that when the array units on the first flexible substrate and the second flexible substrate are arranged in a relative manner, the first protrusions and the second protrusions need to be arranged in a staggered distribution form specifically during assembly; when the array units on the first flexible substrate and the second flexible substrate are in a staggered distribution form, only the two need to be stacked and assembled during assembly.

[0091] As an example, in the step of applying the raw material of the conductive layer to the flexible substrate and curing it, the raw material of the conductive layer is applied to the flexible substrate by spraying.

[0092] In this embodiment, the conductive layer is prepared on the flexible substrate by spraying, so that the obtained resistive pressure sensor has the advantages of high structural stability under high pressure and good reproducibility of test results.

[0093] In other possible embodiments, the raw materials of the conductive layer can also be applied to the flexible substrate by means of drop coating, spin coating, blade coating, dispensing or screen printing.

[0094] It should be noted that the raw materials of the conductive layer include a conductive substance and a solvent, wherein the solvent is selected from at least one of deionized water, isopropyl alcohol and ethanol.

[0095] As an example, after the step of removing the planar substrate and before the step of laying the electrode on the flexible conductive layer, there is also a step of forming a conductive transition layer on the conductive layer.

[0096] It should be noted that the method of forming the conductive transition layer is not limited. For example, inkjet printing or screen printing can be used.

[0097] It should be noted that the raw materials of the conductive transition layer include a conductive substance and a solvent, wherein the solvent is selected from at least one of deionized water, isopropyl alcohol and ethanol.

[0098] As an example, the material of the planar substrate is selected from at least one of polyimide, polycarbonate and polyethylene terephthalate.

[0099] In this embodiment, selecting the material of the planar substrate from the above types has the advantage of facilitating the peeling of the flexible conductive layer from the planar substrate.

[0100] As an example, the raw materials of the encapsulation layer are selected from at least one of hydrogel and polydimethylsiloxane, and the curing method can be ultraviolet curing or heat curing.

[0101] It should be noted that for the processes or steps not specifically described or limited in the preparation process of the resistive pressure sensor, they can be set according to the conventional selection in the art.

[0102] As an example, the process flow chart of the preparation method of the resistive pressure sensor is exemplarily referred to Figure 4 .

[0103] The features and performance of the present application will be further described in detail below in conjunction with embodiments.

[0104] Example 1

[0105] The embodiment of the present application provides a preparation method of a resistive pressure sensor, including the following steps:

[0106] S1 prepares a template by using photolithography and ICP etching techniques. Among them, the surface of the template has grooves of array units, which are used to form protrusions on the flexible substrate after transfer. Specifically, the shape of the grooves is circular, the inner diameter of the grooves is 15 μm, the distance between any two adjacent grooves is 25 μm, and the depth of the grooves is 30 μm. Then, a first flexible substrate with first protrusions and a second flexible substrate with second protrusions are prepared by using the template transfer method. Among them, the projections of the two flexible substrates in the thickness direction are both rectangular, the array units on the two flexible substrates are the same and are distributed in the middle of the corresponding flexible substrates (that is, there are no protrusions in the edge areas of the flexible substrates), and the transferred material is obtained by mixing the base polymer A (polydimethylsiloxane) and the curing agent B in Dow Corning 184 according to a mass ratio of 5:1.

[0107] S2 spins and coats the raw material of the flexible substrate onto a planar substrate and cures it. Among them, the raw material of the flexible substrate is obtained by mixing the base polymer A (polydimethylsiloxane) and the curing agent B in Dow Corning 184 according to a mass ratio of 10:1, and the material of the planar substrate is polycarbonate to form a flexible substrate with a thickness of 17.4 μm on the planar substrate.

[0108] S3 sprays and cures the raw material of the conductive layer onto the flexible substrate. Among them, the raw material of the conductive layer includes a conductive material and a solvent. Among them, the conductive material is silver nanowires with an average length of 10 μm, and the solvent is ethanol to form a conductive layer with a conductive material content of 2 mg / cm 2 on the surface of the flexible substrate; then the planar substrate is removed to obtain a flexible conductive layer.

[0109] S4 forms conductive transition layers in the edge areas on both opposite sides of the conductive layer by using inkjet printing. Among them, the raw material of the conductive transition layer includes a conductive material and a solvent. Among them, the conductive material is silver nanoparticles with a particle size of 15 μm, and the solvent is ethanol to form a conductive transition layer with a conductive material content of 3 mg / cm 2 on the surface of the flexible conductive layer.

[0110] S5 lays electrodes on the surfaces of the two conductive transition layers respectively. Among them, the electrode is composed of conductive glue and copper foil, and one side of the conductive glue is bonded to the surface of the conductive transition layer.

[0111] S6 stacks and assembles the first flexible substrate, the flexible conductive layer with electrodes laid on it, and the second flexible substrate under a confocal microscope in sequence, so that multiple first protrusions on the first flexible substrate and multiple second protrusions on the second flexible substrate are staggered, and the flexible substrate is in contact with the first protrusions and the conductive layer is in contact with the second protrusions to obtain a sensor body. Among them, the electron micrograph of the sensor body can be seen in Figure 5 .

[0112] S7 sprays uncured polydimethylsiloxane onto three of the circumferential sidewalls of the sensor body, and then cures it by heating to obtain a resistive pressure sensor.

[0113] Example 2

[0114] The embodiment of the present application provides a preparation method of a resistive pressure sensor, which is only different from Example 1 in that: in S3, the raw material of the conductive layer is spin-coated onto the flexible substrate at a speed of 800 rpm and cured. Among them, the raw material of the conductive layer includes a conductive material and a solvent. The conductive material is silver nanowires with a length of 10 μm, and the solvent is ethanol, so as to form a conductive layer with a conductive material content of 2 mg / cm 2 on the surface of the flexible substrate; then the planar substrate is removed to obtain a flexible conductive layer.

[0115] Example 3

[0116] The embodiment of the present application provides a preparation method of a resistive pressure sensor, which is only different from Example 1 in that: in S1, a template is prepared by using photolithography and ICP etching techniques. Among them, the surface of the template has grooves of array units for forming protrusions on the flexible substrate after transfer. Specifically, the shape of the grooves is circular, the inner diameter of the grooves is 15 μm, the distance between any two adjacent grooves is 25 μm, and the depth of the grooves is 24 μm.

[0117] Example 4

[0118] The embodiment of the present application provides a preparation method of a resistive pressure sensor, which is only different from Example 1 in that:

[0119] In S2, the raw material of the flexible substrate is spin-coated onto the planar substrate and cured. Among them, the raw material of the flexible substrate is obtained by mixing the base polymer A (polydimethylsiloxane) and the curing agent B in Dow Corning 184 according to a mass ratio of 10:1. The material of the planar substrate is polycarbonate, so as to form a flexible substrate with a thickness of 30 μm on the planar substrate.

[0120] In S3, the raw material of the conductive layer is sprayed onto the flexible substrate and cured. Among them, the raw material of the conductive layer includes a conductive material and a solvent. The conductive material is silver nanowires with a length of 20 μm, and the solvent is ethanol, so as to form a conductive layer with a conductive material content of 2 mg / cm 2 on the surface of the flexible substrate; then the planar substrate is removed to obtain a flexible conductive layer.

[0121] Test Example

[0122] (1) Detection range test

[0123] The resistive pressure sensors prepared in Example 1 and Example 2 were used as test samples respectively, and then the resistance change rates of each sample under different pressures were tested.

[0124] Refer to Figure 6 and Figure 7 It can be seen that the resistive pressure sensors prepared in Example 1 and Example 2 both have high test sensitivities in the pressure range of 0 - 2000 Pa. Especially in the high-pressure range of 1000 - 2000 Pa, they still have high sensitivities (specifically, by calculating the curve slopes in the corresponding ranges, the sensitivity from 0 - 900 Pa is 2.25 kPa -1 and the sensitivity from 900 - 2000 Pa is 0.65 kPa -1 , that is, the resistance always changes with the change of pressure, indicating that the resistive pressure sensor can operate normally in a relatively large pressure range of 0 - 2000 Pa), which shows that the resistive pressure sensor provided by the embodiments of the present application has the advantage of a large test range.

[0125] (2) Reproducibility test

[0126] The resistive pressure sensors prepared in Example 1 and Example 2 were used as test samples respectively, and then the resistance change rates of each sample during the recycling process were tested; among them, the test pressure in Example 1 was 500 Pa, the cyclic test time was 40000 s, and the number of cycles was 4666 times. The test pressures in Example 2 were 500 Pa, 600 Pa, and 700 Pa respectively, and the cyclic test time was 350 s.

[0127] Refer to Figure 8 and Figure 9 It can be seen that the curves of the resistance change rates of the samples in Example 1 are basically the same throughout the test process, and the curves of the resistance change rates of the samples in Example 2 under different test pressures are also basically the same, indicating that using the resistive pressure sensor with a "sandwich structure" provided by the embodiments of the present application for testing has the advantage of good reproducibility of the test results.

[0128] (3) Actual application performance test

[0129] The resistive pressure sensor prepared in Example 1 was used as a test sample, and then the pulses of the human arm before and after cooling were tested.

[0130] Refer to Figure 10 It can be seen that when using the resistive pressure sensor with a "sandwich structure" provided by the embodiments of the present application for pulse testing, the resistance curves before cooling are basically the same, and the resistance curves after cooling are also basically the same, indicating that the resistive pressure sensor provided by the embodiments of the present application also has good test sensitivity and reproducibility during the actual application process.

[0131] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various modifications and changes can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A resistive pressure sensor, characterized in that, Comprising: A sensor body, the sensor body including a first flexible substrate, a second flexible substrate, a flexible conductive layer, and an electrode assembly; one side of the first flexible substrate has a plurality of first protrusions distributed in an array; the second flexible substrate is distributed opposite to the first flexible substrate, and one side of the second flexible substrate close to the first flexible substrate has a plurality of second protrusions distributed in an array, and the plurality of second protrusions and the plurality of first protrusions are all staggered; the flexible conductive layer is located between the first flexible substrate and the second flexible substrate, and the flexible conductive layer includes a flexible substrate and a conductive layer distributed in a stacked manner, the flexible substrate is in contact with the first protrusion, and the conductive layer is in contact with the second protrusion; the electrode assembly includes two electrodes distributed at intervals, and the two electrodes are respectively electrically connected to the conductive layer; A packaging layer, the packaging layer being located on the circumferential side wall of the sensor body.

2. The resistive pressure sensor according to claim 1, characterized in that, The thickness of the flexible substrate in the flexible conductive layer is 17 - 40 μm; Optionally, the content of the conductive material in the conductive layer is 1 to 5 mg / cm 2 .

3. The resistive pressure sensor according to claim 1, wherein The hardness of the first flexible substrate and the second flexible substrate is greater than the hardness of the flexible substrate.

4. The resistive pressure sensor according to any one of claims 1 to 3, characterized in that The shapes and sizes of the plurality of first protrusions and the plurality of second protrusions are all the same; Optionally, the first protrusion is a cylinder, and the diameter of the first protrusion is 10 - 100 μm; Optionally, the distance between any two adjacent first protrusions and the distance between any two adjacent second protrusions are both 10 - 100 μm; Optionally, the height of the first protrusion is 20 - 200 μm.

5. The resistive pressure sensor according to any one of claims 1 to 3, characterized in that, The two electrodes are respectively electrically connected to the conductive layer through a conductive transition layer, and the content of the conductive material in the conductive transition layer is greater than the content of the conductive material in the conductive layer; Optionally, the conductive material in the conductive layer is selected from at least one of silver, copper, nickel, and platinum; Optionally, the conductive material in the conductive transition layer is selected from at least one of silver and gold.

6. The resistive pressure sensor according to any one of claims 1 to 3, characterized in that, The materials of the first flexible substrate and the second flexible substrate are the same; Optionally, the material of the first flexible substrate is selected from at least one of polydimethylsiloxane, polyimide, and hydrogel.

7. The resistive pressure sensor according to any one of claims 1 to 3, characterized in that The packaging layer is located on a part of the circumferential side wall of the sensor body.

8. The resistive pressure sensor according to any one of claims 1 to 3, characterized in that The second flexible substrate includes an array unit in the middle and an edge area surrounding the array unit, the array unit includes a plurality of second protrusions distributed in an array, and the electrode assembly is located in the area corresponding to the edge area of the conductive layer.

9. A method for preparing a resistive pressure sensor according to any one of claims 1 to 8, characterized in that, Including the following steps: Using a template transfer technology to prepare the first flexible substrate with the first protrusions and the second flexible substrate with the second protrusions; Applying the raw material of the flexible substrate to a planar substrate and curing it to form the flexible substrate on the planar substrate; Then applying the raw material of the conductive layer to the flexible substrate and curing it to form the conductive layer on the surface of the flexible substrate; Then removing the planar substrate to obtain the flexible conductive layer; Laying the two electrodes at intervals on the surface of the conductive layer in the flexible conductive layer; Stack the first flexible substrate, the flexible conductive layer after laying the electrodes, and the second flexible substrate in sequence, so that the plurality of first protrusions on the first flexible substrate and the plurality of second protrusions on the second flexible substrate are staggered, and the flexible substrate contacts the first protrusions and the conductive layer contacts the second protrusions, to obtain the sensor body; Apply the raw material of the encapsulation layer to the circumferential side wall of the sensor body and perform a curing treatment to form the encapsulation layer on the circumferential side wall of the sensor body, to obtain the resistive pressure sensor.

10. The manufacturing method of the resistive pressure sensor according to claim 9, characterized in that, In the step of applying the raw material of the conductive layer to the flexible substrate and curing it, the raw material of the conductive layer is applied to the flexible substrate by spraying; Or / and, the material of the planar substrate is selected from at least one of polyimide, polycarbonate, and polyethylene terephthalate.

Images