Pressure sensor, preparation method and pulse measuring device

Abstract

The invention discloses a pressure sensor, a preparation method and a pulse measuring device. According to the technical scheme, when pressure is detected, a force application object directly acts on the protrusions, and the contact area of the force application object and the protrusions is smaller than the direct contact area of the force application object and the plane layer, so that the arrangement of the protrusions reduces the stress area of the pressure sensor when the force application object acts on the pressure sensor, increases the pressure intensity, and improves the detection accuracy. According to the pressure sensor, the first friction layer and the second friction layer are arranged, so that the contact area of the first friction layer and the second friction layer can be ensured under weak force, the detection threshold value of the pressure sensor is reduced, meanwhile, resistance generated by air of the second channel in the insulating spacer layer to the first friction layer is balanced through the first channel, and the response capability of the pressure sensor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure sensors, and in particular to a pressure sensor, a preparation method and a measuring device. Background Art

[0002] Based on the coupling effect of triboelectric charging and electrostatic induction, the friction nanogenerator can directly convert mechanical energy into electrical energy. Based on the principle of the friction nanogenerator converting mechanical energy into electrical energy, a pressure sensor is proposed. Compared with general resistive, capacitive and piezoelectric wearable sensors, it has the advantages of simple structure, high efficiency, low cost and self-power supply. Therefore, it is widely used in some fields.

[0003] Currently, commonly used pressure sensors are affected by their structure and size, and when used, there is a problem of incompatibility between the low detection threshold and the response capability.

[0004] Therefore, in terms of the sensitivity of the sensor to weak forces, the pressure sensors in the prior art still need to be improved and developed. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a pressure sensor, a preparation method and a pulse measurement device to solve the problem in the prior art that the pressure sensor has low detection threshold and response capability that are difficult to be compatible.

[0006] The technical solution adopted by the present invention to solve the technical problem is to provide a pressure sensor, comprising:

[0007] a first substrate layer;

[0008] a first conductive layer provided on the lower surface of the first substrate layer; and

[0009] a first friction layer disposed in contact with a lower surface of the first conductive layer;

[0010] a protrusion provided on the upper surface of the first substrate layer, configured to contact a force-applying object and transmit external force to the first friction layer;

[0011] a second substrate layer;

[0012] a second conductive layer provided on the upper surface of the second substrate layer;

[0013] a second friction layer disposed in contact with the upper surface of the second conductive layer;

[0014] an insulating spacer layer disposed between the first friction layer and the second friction layer, the insulating spacer layer being provided with a first channel and a second channel penetrating the insulating spacer layer, the second channel being in communication with the exterior of the pressure sensor via the first channel, the first channel being used to balance the air pressure in the second channel with the air pressure outside the pressure sensor;

[0015] The second friction layer and the first friction layer are made of triboelectric materials with opposite electrical properties. Under the action of an external force, at least a portion of the surface of the first friction layer contacts a portion of the surface of the second friction layer through the second channel. When the external force disappears, the first friction layer and the second friction layer separate.

[0016] The area where the protrusion contacts the force-applying object is smaller than the area where the force-applying object directly contacts a planar layer.

[0017] The present invention further provides that the protrusion includes a protrusion with a cross-shaped structure.

[0018] The present invention further provides that the first friction layer comprises: a polydimethylsiloxane film with a smooth surface;

[0019] The second friction layer includes a fluorinated ethylene propylene film with a smooth surface.

[0020] The present invention further provides that the first substrate layer and the second substrate layer are both made of polyethylene terephthalate film.

[0021] The present invention further provides that the insulating spacer layer includes: a plurality of stacked polyimide double-sided adhesives.

[0022] The present invention further provides that the thickness of the insulating spacer layer ranges from 0.4 mm to 0.8 mm.

[0023] The present invention further provides that the first channels are respectively provided on both sides of the second channel, and the first channels are arranged opposite to each other.

[0024] The present invention further provides that the upper surface of the first conductive layer and the lower surface of the first conductive layer are respectively coated with copper glue;

[0025] The upper surface of the second conductive layer and the lower surface of the second conductive layer are respectively coated with copper paste.

[0026] The present invention also provides a method for preparing the pressure sensor as described above, comprising:

[0027] Providing a protrusion, a first friction layer, a first conductive layer, a first substrate layer, a second friction layer, a second conductive layer, a second substrate layer and an insulating spacer layer;

[0028] Adhere the first friction layer to the lower surface of the first conductive layer;

[0029] Adhere the first substrate layer to the upper surface of the first conductive layer;

[0030] adhering the second friction layer to the upper surface of the second conductive layer;

[0031] pasting the second substrate layer on the lower surface of the second conductive layer;

[0032] Adhere the protrusion to the upper surface of the first substrate layer;

[0033] Adhere the lower surface of the first friction layer to the upper surface of the insulating spacer layer;

[0034] The upper surface of the second friction layer is adhered to the lower surface of the insulating spacer layer.

[0035] The present invention also provides a pulse measurement device, comprising: a shell, a signal acquisition module arranged in the shell, and the pressure sensor as described above, the signal acquisition module being electrically connected to the first conductive layer and the second conductive layer in the pressure sensor as described above, and the signal acquisition module being used to collect the electrical signal output by the pressure sensor as described above.

[0036] The beneficial effects of the present invention are:

[0037] Disclosed herein are a pressure sensor, a preparation method, and a pulse measurement device. The pressure sensor includes a first substrate layer; a first conductive layer disposed on the lower surface of the first substrate layer; a first friction layer disposed in contact with the lower surface of the first conductive layer; a protrusion disposed on the upper surface of the first substrate layer, configured to contact a force-applying object and transmit external force to the first friction layer; a second substrate layer; a second conductive layer disposed on the upper surface of the second substrate layer; a second friction layer disposed in contact with the upper surface of the second conductive layer; and an insulating spacer disposed between the first and second friction layers, the insulating spacer layer having a first channel and a second channel extending through the insulating spacer layer, the second channel communicating with the exterior of the pressure sensor via the first channel, and the first channel balancing the air pressure within the second channel with the air pressure outside the pressure sensor. The second friction layer and the first friction layer are made of a triboelectric material having opposite electrical properties. Under the action of an external force, at least a portion of the surface of the first friction layer contacts a portion of the surface of the second friction layer via the second channel, and the first and second friction layers separate after the external force disappears. The area of ​​contact between the protrusion and the force-applying object is smaller than the area of ​​direct contact between the force-applying object and a planar layer. In the technical solution of the present invention, when detecting pressure, the force-applying object acts directly on the protrusion. Since the contact area between the force-applying object and the protrusion is smaller than the contact area between the force-applying object and a planar layer, the setting of the protrusion reduces the force-bearing area of ​​the pressure sensor when the force-applying object acts on the pressure sensor, increases the pressure, and ensures the contact area between the first friction layer and the second friction layer even when the force is weak, thereby lowering the detection threshold of the pressure sensor. At the same time, the resistance generated by the air in the second channel in the insulating spacer layer to the first friction layer is balanced through the first channel, thereby improving the response capability of the pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary personnel in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0039] Figure 1 It is a structural diagram of the pressure sensor of the present invention.

[0040] Figure 2 It is a flow chart of the method for preparing the pressure sensor of the present invention.

[0041] Figure 3 It is a working principle diagram of the pressure sensor of the present invention.

[0042] Figure 4 It is the output characteristic of the pressure sensor to pressure in one embodiment of the present invention.

[0043] Figure 5 This is the response of the pressure sensor to a pressure within 0.25N in one embodiment of the present invention.

[0044] Figure 6 FIG. 4 is the response of the pressure sensor to lighter weight glass particles in one embodiment of the present invention.

[0045] Figure 7 The figure shows the measurement of radial artery pulse waves of a person before and after exercise by a pressure sensor in one embodiment of the present invention.

[0046] The marks in the accompanying drawings are: 1, protrusion; 2, first substrate layer; 3, first conductive layer; 4, first friction layer; 5, insulating spacer layer; 51, first channel; 52, second channel; 6, second friction layer; 7, second conductive layer; 8, second substrate layer. DETAILED DESCRIPTION

[0047] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings and are constructed and operated in specific directions. They are only for the convenience of describing the technical solution and do not indicate that the devices or components referred to must have specific directions. Therefore, they should not be understood as limiting the present invention.

[0048] like Figure 1 Figure 1 shows a pressure sensor provided by the present invention, which is based on the contact-separation triboelectric nanogenerator principle. The pressure sensor may include a first substrate layer 2, a first conductive layer 3, a first friction layer 4, a protrusion 1, a second substrate layer 8, a second conductive layer 7, a second friction layer 6, and an insulating spacer layer 5.

[0049] Among them, the second substrate layer 8, the second conductive layer 7, the second friction layer 6, the insulating spacer layer 5, the first friction layer 4, the first conductive layer 3, the first substrate layer 2 and the protrusion 1 are arranged in sequence from bottom to top, that is, the first conductive layer 3 is provided on the lower surface of the first substrate layer 2, the first friction layer 4 is provided in contact with the lower surface of the first conductive layer 3, the protrusion 1 is provided on the upper surface of the first substrate layer 2, the second conductive layer 7 is provided on the upper surface of the second substrate layer 8, the second friction layer 6 is provided in contact with the upper surface of the second conductive layer 7, and the insulating spacer layer 5 is provided between the first friction layer 4 and the second friction layer 6; the protrusion 1 is used to contact the force-applying object and transmit the external force to the first friction layer 4; The insulating spacer layer 5 is provided with a first channel 51 and a second channel 52 that passes through the insulating spacer layer 5. The second channel 52 is connected to the outside of the pressure sensor through the first channel 51. The first channel 51 is used to balance the air pressure in the second channel 52 and the air pressure outside the pressure sensor. The material of the second friction layer 6 and the material of the first friction layer 4 are triboelectric materials with opposite electrical properties. Under the action of an external force, at least a portion of the surface of the first friction layer 4 contacts a portion of the surface of the second friction layer 6 through the second channel 52, and the first friction layer 4 and the second friction layer 6 separate after the external force disappears. The area of ​​contact between the protrusion 1 and the force-applying object is smaller than the area of ​​direct contact between the force-applying object and a planar layer.

[0050] During pressure detection, a force-applying object acts on the protrusion 1, and the external force is transmitted to the first friction layer 4 through the protrusion 1 via the first substrate and the first conductive layer 3. When the external force acts on the first friction layer 4, under the action of the external force, a portion of the surface of the first friction layer 4 contacts a portion of the surface of the second friction layer 6 through the second channel 52. After the external force disappears, the first friction layer 4 separates from the second friction layer 6, that is, the first friction layer 4 and the second friction layer 6 perform a contact-separation motion. Since the first friction layer 4 and the second friction layer 6 are triboelectric materials with opposite electrical properties, when the first friction layer 4 and the second friction layer 6 perform a contact-separation motion, charges of different polarities are generated due to the triboelectric effect. When the first conductive layer 3 and the second conductive layer 7 are connected via a load, a voltage signal can be detected at both ends of the load. That is, a voltage signal is generated when the first friction layer 4 and the second friction layer 6 perform a contact-separation motion, and the pressure magnitude is fed back through this voltage signal.

[0051] In this embodiment, when detecting pressure, the force-applying object directly acts on the protrusion 1. Since the contact area between the force-applying object and the protrusion 1 is smaller than the contact area between the force-applying object and a planar layer, the provision of the protrusion 1 reduces the force-bearing area of ​​the pressure sensor when the force-applying object acts on the pressure sensor, increases the pressure, and ensures the contact area between the first friction layer 4 and the second friction layer 6 even when the force is weak, thereby lowering the detection threshold of the pressure sensor. At the same time, the resistance generated by the air in the second channel 52 in the insulating spacer layer 5 on the first friction layer 4 is balanced through the first channel 51, thereby improving the response capability of the pressure sensor.

[0052] In some embodiments, the structure of the protrusion 1 may include a cross-shaped structure.

[0053] In this embodiment, when the protrusion 1 is set, polydimethylsiloxane (PDMS) can be selected but not limited to as the design raw material of the protrusion 1. During the setting process, a cross-shaped mold can be 3D printed, and a polydimethylsiloxane solution can be poured into the mold. After vacuuming, the mold is cured to obtain a protrusion 1.

[0054] Of course, the structure of the protrusion 1 is not limited to the above-mentioned cross-shaped structure. For example, the protrusion 1 can also be set as a "I"-shaped structure. When setting, multiple "I"-shaped structures are set on the upper surface of the first substrate layer 2.

[0055] In some embodiments, the material of the first friction layer 4 may include a polydimethylsiloxane film with a smooth surface; the material of the second friction layer 6 may include a fluorinated ethylene propylene (FEP) film with a smooth surface.

[0056] Specifically, when selecting the material of the first friction layer 4 and the material of the second friction layer 6, it is necessary to consider that the material of the first friction layer 4 and the material of the second friction layer 6 are triboelectric materials with opposite electrical properties, and the first friction layer 4 and the second friction layer 6 are prone to charge transfer after contact with each other. At the same time, the mechanical properties, flexibility, rigidity and processability of the friction layers (the first friction layer 4 and the second friction layer 6) must also be considered. In this embodiment, based on the existing statistical triboelectric sequence, the material of the first friction layer 4 is preferably polydimethylsiloxane film, and the material of the second friction layer 6 is preferably fluorinated ethylene propylene film relative to the material of the first friction layer 4 (polydimethylsiloxane film has strong processability, simple preparation and good flexibility, and in the triboelectric sequence, polydimethylsiloxane film and fluorinated ethylene propylene film are far apart).

[0057] Here, it should be noted that the smooth surface means that the surfaces of the first friction layer 4 and the second friction layer 6 have no microstructure.

[0058] In some embodiments, the first substrate layer 2 and the second substrate layer 8 are both made of polyethylene glycol terephthalate (PET) films.

[0059] In this embodiment, the film of ethylene terephthalate can make the first friction layer 4 and the second friction layer 6 have just the right rigidity and elasticity, so that the first friction layer 4 and the second friction layer 6 can be fully in contact and completely separated.

[0060] In some embodiments, the insulating spacer layer 5 may include a plurality of stacked polyimide double-sided adhesive tapes.

[0061] Specifically, several layers of polyimide double-sided tape (PI) can be stacked to form an insulating spacer layer 5. When the insulating spacer layer 5 is set, a polyimide double-sided tape with a thickness of but not limited to 0.08 mm is used. A second channel 52 is set in the formed insulating spacer layer 5, and a first channel 51 connecting the second channel 52 and the outside of the pressure sensor is set on one side of the insulating spacer layer 5.

[0062] In some embodiments, the thickness of the insulating spacer layer 5 ranges from 0.4 mm to 0.8 mm. For example, the thickness of the insulating spacer layer 5 is 0.56 mm, 0.64 mm, 0.72 mm, etc. In a preferred embodiment, the thickness of the insulating spacer layer 5 is 0.64 mm. That is, the insulating spacer layer 5 is formed by stacking eight layers of polyimide double-sided tape. The insulating spacer layer 5 can fix and separate the first friction layer 4 and the second friction layer 6, so that there is space for the first friction layer 4 and the second friction layer 6 to complete the contact and separation action.

[0063] In some embodiments, when the first channel 51 is set, two first channels 51 can be set on both sides of the second channel 52, and the two first channels 51 are symmetrically arranged. Of course, the first channels 51 can also be set to other numbers. For example, the first channels 51 are set to four, and the four first channels 51 are symmetrically arranged on both sides of the second channel 52 in a group of two. The symmetrical arrangement of the first channels 51 can better balance the air pressure and further ensure the sensitivity and responsiveness of the pressure sensor.

[0064] In some embodiments, the upper surface and the lower surface of the first conductive layer 3 may be coated with copper paste respectively; the upper surface and the lower surface of the second conductive layer 7 may be coated with copper paste respectively.

[0065] Specifically, when the first conductive layer 3 is set, the upper surface and the lower surface of the first conductive layer 3 are coated with copper glue, so that while ensuring the conductive performance, it has stickiness on both sides, so as to facilitate the bonding of the first substrate layer 2 and the first conductive layer 3, and the bonding of the first friction layer 4 and the first conductive layer 3; similarly, when the second conductive layer 7 is set, the upper surface and the lower surface of the second conductive layer 7 are coated with copper glue, so that while ensuring the conductive performance, it has stickiness on both sides, so as to facilitate the bonding of the second substrate layer 8 and the first conductive layer 3, and the bonding of the second friction layer 6 and the first conductive layer 3.

[0066] In order to further explain the working principle of the pressure sensor, an example of applying the pressure sensor to pulse detection is used for illustration.

[0067] For example, Figure 3 As shown, the first conductive layer 3 and the second conductive layer 7 of the pressure sensor are connected via a load resistor. During detection, the protrusion 1 of the pressure sensor is on the side close to the human skin. When the pulse wave is transmitted along the blood vessel artery to the sensing part of the pressure sensor (i.e., the position of the protrusion 1), the pressure sensor is subjected to external force, causing the first friction layer 4 and the second friction layer 6 to contact each other. Due to the triboelectric effect, charge transfer occurs on the contact surface when the first friction layer 4 and the second friction layer 6 come into contact. The greater the applied force, the larger the contact area between the first friction layer 4 and the second friction layer 6. When the first friction layer 4 and the second friction layer 6 come into contact, electrons transfer from the surface of the second friction layer 6 to the surface of the first friction layer 4 (the larger the contact area, the greater the amount of charge transferred), generating negative and positive charges on the surfaces of the first friction layer 4 and the second friction layer 6, respectively. At this time, the first friction layer 4 and the second friction layer 6 are electrically neutral as a whole, and no current is generated in the external circuit, that is, no voltage is generated on the load resistor. When the pulse wave moves away from the sensing component of the pressure sensor (that is, when the external force applied to the protrusion 1 is released), the first friction layer 4 and the second friction layer 6 separate, thereby generating a potential difference between the first friction layer 4 and the second friction layer 6. To balance the potential difference caused by friction between the first friction layer 4 and the second friction layer 6, electrons in the first conductive layer 3 flow from the first friction layer 4 to the second friction layer 6 through the external circuit (that is, the load resistor), thereby generating a current and an electrical signal. When the next pulse wave approaches the sensing component of the pressure sensor, the negatively charged first friction layer approaches the second friction layer 6 due to the application of external pressure. Due to the effect of electrostatic induction, when the first friction layer 4 and the second friction layer 6 approach each other, the electrons in the second conductive layer 7 will flow from the second friction layer 6 to the first friction layer 4 through the external circuit, generating current. In this way, as the pulse wave continues to pass through the sensing part of the pressure sensor, the first friction layer 4 and the second friction layer 6 in the pressure sensor repeatedly complete the contact and separation action, and generate an AC signal that can reflect the conduction state of the pulse wave.

[0068] This pressure sensor can be applied to pulse measurement devices, human posture recognition devices, etc., and can be widely used in human-computer interaction, biomedicine and other fields, and has great application prospects.

[0069] In some embodiments, as Figure 2 As shown, the present invention also provides a method for preparing the above-mentioned pressure sensor, comprising the steps of:

[0070] S1, providing a protrusion, a first friction layer, a first conductive layer, a first substrate layer, a second friction layer, a second conductive layer, a second substrate layer and an insulating spacer layer;

[0071] S2, adhering the first friction layer to the lower surface of the first conductive layer;

[0072] S3, attaching the first substrate layer to the upper surface of the first conductive layer;

[0073] S4, adhering the second friction layer to the upper surface of the second conductive layer;

[0074] S5, attaching the second substrate layer to the lower surface of the second conductive layer;

[0075] S6, sticking the protrusions to the upper surface of the first substrate layer;

[0076] S7, adhering the lower surface of the first friction layer to the upper surface of the insulating spacer layer;

[0077] S8. Adhere the upper surface of the second friction layer to the lower surface of the insulating spacer layer.

[0078] In this embodiment, first, the required materials (a protrusion, a first friction layer, a first conductive layer, a first substrate layer, a second friction layer, a second conductive layer, a second substrate layer and an insulating spacer layer) are provided.

[0079] Specifically, when preparing the protrusion, a cross-shaped mold can be 3D printed, and a polydimethylsiloxane solution can be poured into the mold. After vacuuming, the mold is cured to obtain a protrusion; when preparing the first friction layer, a substrate made of but not limited to polyethylene terephthalate is provided, and then the polydimethylsiloxane solution is spin-coated on the polyethylene terephthalate substrate and cured to obtain a polydimethylsiloxane film with a smooth surface after curing; the first conductive layer can be any conductive metal material, for example, the material of the first conductive layer can be copper; for example, the material of the first conductive layer can be aluminum; preferably, the material of the first conductive layer is copper; when setting the second conductive layer, the setting method of the first conductive layer can be referred to, and no further details will be given here; the first substrate layer and the second substrate layer can be made of a film made of polyethylene terephthalate, and the material is polyethylene terephthalate The film is a film made by the prior art. During its use, technical personnel in this field can select polyethylene glycol terephthalate film according to thickness requirements and cut it into the required shape; the insulating spacer layer can be formed by stacking several layers of polyimide double-sided tape to form an insulating spacer layer. When setting it, technical personnel in this field can determine the required thickness of the polyimide double-sided tape according to the thickness of the insulating spacer layer. For example, when the thickness of the insulating spacer layer is 0.64 mm, a polyimide double-sided tape with a thickness of 0.08 mm can be selected. After the insulating spacer layer is set, the required first channel and second channel need to be set on the insulating spacer layer in advance; the second friction layer can be made of fluorinated ethylene propylene film. Fluorinated ethylene propylene film is a film made by the prior art. When selecting it, technical personnel in this field can select fluorinated ethylene propylene film according to thickness requirements and cut it into the required shape.

[0080] Here, it should be noted that when selecting the first conductive layer, while considering conductivity, it is also required that it can transfer the external force applied to the protrusion to the first friction layer; in addition, the upper surface of the first conductive layer and the lower surface of the first conductive layer are respectively covered with copper glue, and similarly, the upper surface of the second conductive layer and the lower surface of the second conductive layer are respectively covered with copper glue. The double-sided copper glue ensures conductivity while making both sides have stickiness.

[0081] Afterwards, since the upper surface of the first conductive layer and the lower surface of the first conductive layer are respectively covered with copper glue, the first friction layer can be directly adhered to the lower surface of the first conductive layer, and the first substrate layer can be adhered to the upper surface of the first conductive layer; similarly, since the upper surface of the second conductive layer and the lower surface of the second conductive layer are respectively covered with copper glue, the second friction layer can be directly adhered to the upper surface of the second conductive layer, and the second substrate layer can be adhered to the lower surface of the second conductive layer; further, by gluing, the lower surface of the first friction layer is adhered to the upper surface of the insulating spacer layer, and the upper surface of the second friction layer is adhered to the lower surface of the insulating spacer layer.

[0082] Furthermore, after the first friction layer and the second friction layer are connected through the insulating spacer layer, the protrusions are finally adhered to the upper surface of the first substrate layer by gluing. At this point, the pressure sensor is completed.

[0083] In order to further explain the preparation method of the pressure sensor, the following preparation example is used for illustration.

[0084] In Example 1, a 0.1mm thick ethylene terephthalate substrate was provided. A polydimethylsiloxane solution was spin-coated onto the ethylene terephthalate substrate and cured to produce a smooth 0.1mm thick polydimethylsiloxane film. A 0.1mm thick fluorinated ethylene propylene film was also provided. The polydimethylsiloxane film and the fluorinated ethylene propylene film were cut into 15mm x 25mm dimensions. The first conductive layer and the second conductive layer are cut into suitable shapes using a laser cutting machine (the upper surface and the lower surface of the first conductive layer and the upper surface and the lower surface of the second conductive layer are respectively covered with copper glue, for example, two copper films with copper glue on both sides). After cutting, one side of the first conductive layer (which can be regarded as the upper surface of the first conductive layer) is first pasted on the lower surface of a first substrate layer made of polyethylene terephthalate with a thickness of about 0.1 mm, and then the other side of the first conductive layer (which can be regarded as the lower surface of the first conductive layer) is pasted on the upper surface of the polydimethylsiloxane film (the first friction layer). Similarly, one side of the second conductive layer (which can be regarded as the upper surface of the second conductive layer) is pasted on the upper surface of the polydimethylsiloxane film (the first friction layer). ) is pasted on the lower surface of the fluorinated ethylene propylene film (the second friction layer), and the other side of the second conductive layer (which can be regarded as the lower surface of the second conductive layer) is pasted on the upper surface of the second substrate layer of polyethylene terephthalate with a thickness of about 0.1mm; further, the polydimethylsiloxane film (first friction layer) pasted with the first substrate layer and the first conductive layer and the fluorinated ethylene propylene film (second friction layer) pasted with the second substrate layer and the second conductive layer are pasted together through an insulating spacer layer, wherein the insulating spacer layer adopts a single layer of polyimide double-sided tape with a thickness of 0.08mm, and a total of ten layers are stacked to form a 0.8mm insulating spacer layer. Finally, a cross-shaped mold is 3D printed, and a polydimethylsiloxane solution is poured into the mold. After vacuuming, a protrusion is obtained by curing, and the produced protrusion is pasted on the upper surface of the first substrate layer. wherein, the size of the produced protrusion is the size of a cross structure (length 22mm, width 12mm, height 2mm).

[0085] Here, it should be noted that when the polydimethylsiloxane film (first friction layer) with the first substrate layer and the first conductive layer is pasted with the fluorinated ethylene propylene film (second friction layer) with the second substrate layer and the second conductive layer is pasted through the insulating spacer layer, it is necessary to use a laser cutting machine to cut the 0.08mm polyimide double-sided tape to form the first channel and the second channel according to the specific structure, size and number of the first channel set on the insulating spacer layer in advance. For example, the second channel can be a rectangular channel running through the upper and lower surfaces of the insulating spacer layer, and the first channel can be a rectangular channel of 1mm×0.6mm, wherein two first channels can be set, which are symmetrically arranged on both sides of the second channel; of course, the second channel and the first channel can also be channels of other structures that can achieve the above functions. When setting, those skilled in the art can determine the specific structure, size or number of the first channel and the second channel according to actual needs, and no further details will be given here.

[0086] In Example 2, a 0.1 mm thick polyethylene terephthalate substrate was provided. A polydimethylsiloxane solution was spin-coated onto the polyethylene terephthalate substrate and cured to produce a smooth polydimethylsiloxane film approximately 0.1 mm thick. A 0.1 mm thick fluorinated ethylene propylene film was also provided. The polydimethylsiloxane film and the fluorinated ethylene propylene film were cut into 15 mm x 25 mm dimensions. The first conductive layer and the second conductive layer are cut into suitable shapes using a laser cutting machine (the upper surface and the lower surface of the first conductive layer and the upper surface and the lower surface of the second conductive layer are respectively covered with copper glue, for example, two copper films with copper glue on both sides). After cutting, one side of the first conductive layer (which can be regarded as the upper surface of the first conductive layer) is first pasted on the lower surface of a first substrate layer made of polyethylene terephthalate with a thickness of about 0.1 mm, and then the other side of the first conductive layer (which can be regarded as the lower surface of the first conductive layer) is pasted on the upper surface of the polydimethylsiloxane film (the first friction layer). Similarly, one side of the second conductive layer (which can be regarded as the upper surface of the second conductive layer) is pasted on the upper surface of the polydimethylsiloxane film (the first friction layer). ) is pasted on the lower surface of the fluorinated ethylene propylene film (the second friction layer), and the other side of the second conductive layer (which can be regarded as the lower surface of the second conductive layer) is pasted on the upper surface of the second substrate layer made of polyethylene terephthalate with a thickness of about 0.1mm; further, the polydimethylsiloxane film (first friction layer) pasted with the first substrate layer and the first conductive layer and the fluorinated ethylene propylene film (second friction layer) pasted with the second substrate layer and the second conductive layer are pasted together through an insulating spacer layer, wherein the insulating spacer layer adopts a single layer of polyimide double-sided tape with a thickness of 0.08mm, and a total of six layers are stacked to form a 0.48mm insulating spacer layer. Finally, a cross-shaped mold is 3D printed, and a polydimethylsiloxane solution is poured into the mold. After vacuuming, it is cured to obtain a protrusion, and the produced protrusion is pasted on the upper surface of the first substrate layer. wherein, the size of the produced protrusion is the size of a cross structure (length 22mm, width 12mm, height 2mm).

[0087] Here, it should be noted that when the polydimethylsiloxane film (first friction layer) with the first substrate layer and the first conductive layer is pasted with the fluorinated ethylene propylene film (second friction layer) with the second substrate layer and the second conductive layer is pasted through the insulating spacer layer, it is necessary to use a laser cutting machine to cut the 0.08mm polyimide double-sided tape to form the first channel and the second channel according to the specific structure, size and number of the first channel set on the insulating spacer layer in advance. For example, the second channel can be a rectangular channel running through the upper and lower surfaces of the insulating spacer layer, and the first channel can be a rectangular channel of 1mm×0.6mm, wherein two first channels can be set, which are symmetrically arranged on both sides of the second channel; of course, the second channel and the first channel can also be channels of other structures that can achieve the above functions. When setting, those skilled in the art can determine the specific structure, size or number of the first channel and the second channel according to actual needs, and no further details will be given here.

[0088] In Example 3, a 0.1 mm thick polyethylene terephthalate substrate was provided. A polydimethylsiloxane solution was spin-coated onto the polyethylene terephthalate substrate and cured to produce a smooth polydimethylsiloxane film approximately 0.1 mm thick. A 0.1 mm thick fluorinated ethylene propylene film was also provided. The polydimethylsiloxane film and the fluorinated ethylene propylene film were cut into 15 mm x 25 mm dimensions. The first conductive layer and the second conductive layer are cut into suitable shapes using a laser cutting machine (the upper surface and the lower surface of the first conductive layer and the upper surface and the lower surface of the second conductive layer are respectively covered with copper glue, for example, two copper films with copper glue on both sides). After cutting, one side of the first conductive layer (which can be regarded as the upper surface of the first conductive layer) is first pasted on the lower surface of a first substrate layer made of polyethylene terephthalate with a thickness of about 0.1 mm, and then the other side of the first conductive layer (which can be regarded as the lower surface of the first conductive layer) is pasted on the upper surface of the polydimethylsiloxane film (the first friction layer). Similarly, one side of the second conductive layer (which can be regarded as the upper surface of the second conductive layer) is pasted on the upper surface of the polydimethylsiloxane film (the first friction layer). ) is pasted on the lower surface of the fluorinated ethylene propylene film (the second friction layer), and the other side of the second conductive layer (which can be regarded as the lower surface of the second conductive layer) is pasted on the upper surface of the second substrate layer made of polyethylene terephthalate with a thickness of about 0.1mm; further, the polydimethylsiloxane film (first friction layer) pasted with the first substrate layer and the first conductive layer and the fluorinated ethylene propylene film (second friction layer) pasted with the second substrate layer and the second conductive layer are pasted together through an insulating spacer layer, wherein the insulating spacer layer adopts a single layer of polyimide double-sided tape with a thickness of 0.08mm, and a total of eight layers are stacked to form an insulating spacer layer of 0.64mm. Finally, a cross-shaped mold is 3D printed, and a polydimethylsiloxane solution is poured into the mold. After vacuuming, a protrusion is obtained by curing, and the produced protrusion is pasted on the upper surface of the first substrate layer. wherein, the size of the produced protrusion is the size of a cross structure (length 22mm, width 12mm, height 2mm).

[0089] Here, it should be noted that when the polydimethylsiloxane film (first friction layer) with the first substrate layer and the first conductive layer is pasted with the fluorinated ethylene propylene film (second friction layer) with the second substrate layer and the second conductive layer is pasted through the insulating spacer layer, it is necessary to use a laser cutting machine to cut the 0.08mm polyimide double-sided tape to form the first channel and the second channel according to the specific structure, size and number of the first channel set on the insulating spacer layer in advance. For example, the second channel can be a rectangular channel running through the upper and lower surfaces of the insulating spacer layer, and the first channel can be a rectangular channel of 1mm×0.6mm, wherein two first channels can be set, which are symmetrically arranged on both sides of the second channel; of course, the second channel and the first channel can also be channels of other structures that can achieve the above functions. When setting, those skilled in the art can determine the specific structure, size or number of the first channel and the second channel according to actual needs, and no further details will be given here.

[0090] Based on the above examples 1, 2 and 3, it can be seen that the pressure sensor has a simple structure and low manufacturing cost.

[0091] In order to further study the performance of the pressure sensor, a performance test was conducted on the pressure sensor manufactured using the parameters of Example 3.

[0092] Specifically, the first conductive layer and the second conductive layer are respectively led out through wires, and the linear motor controls the pressure head to press the pressure sensor back and forth. When pressing starts, the pressure head and the pressure sensor are at the critical point of contact, and the pressure head is connected to the pressure gauge; when pressing, the first friction layer and the second friction layer go from no contact to partial contact; when the pressing reaches a specified depth, the contact area between the first friction layer and the second friction layer reaches the maximum, and the pressure head begins to lift, at which time the maximum voltage output is reached. The pressure at this time can be obtained through the pressure gauge, and the output performance of the pressure sensor can be obtained by specifying different pressing depths.

[0093] like Figure 4 As shown, Figure 4 The output characteristics of the pressure sensor to pressure are shown. Figure 4 Among them, the output characteristic corresponding to A is the output characteristic of the pressure sensor to pressure when the pressure is 0.05N; the output characteristic corresponding to B is the output characteristic of the pressure sensor to pressure when the pressure is 0.1N; the output characteristic corresponding to C is the output characteristic of the pressure sensor to pressure when the pressure is 0.2N; the output characteristic corresponding to D is the output characteristic of the pressure sensor to pressure when the pressure is 0.5N; the output characteristic corresponding to E is the output characteristic of the pressure sensor to pressure when the pressure is 1N.

[0094] like Figure 5 As shown, Figure 5 The response of the pressure sensor to a pressure within 0.25N is shown.

[0095] like Figure 6 As shown, Figure 6 The response of the pressure sensor to light glass particles is demonstrated. The measurement method is to use tweezers to pick up glass particles of different weights, place them at a height of 2 cm above the table, let them fall freely, and measure the output signal of the sensor at the moment of touching the sensor. Figure 6 In the figure, the voltage output waveform corresponding to F is the voltage output waveform of the pressure sensor when the weight of the glass particles is 9 mg; the voltage output waveform corresponding to G is the voltage output waveform of the pressure sensor when the weight of the glass particles is 20 mg; the voltage output waveform corresponding to H is the voltage output waveform of the pressure sensor when the weight of the glass particles is 30 mg.

[0096] like Figure 7 As shown, Figure 7 The pressure sensor measures the radial artery pulse wave before and after exercise. It can be seen that the pressure sensor provided by the present invention has a good output capability in terms of response to weak forces, and also has a stable output in daily application scenarios such as pulse wave detection. Figure 7 In FIG, the voltage output waveform corresponding to I is the radial artery pulse wave measured by the pressure sensor before exercise; the voltage output waveform corresponding to J is the radial artery pulse wave measured by the pressure sensor after exercise.

[0097] In some embodiments, the present invention also provides a pulse measurement device, comprising: a shell, a signal acquisition module arranged in the shell, and the pressure sensor as described above, the signal acquisition module being electrically connected to the first conductive layer and the second conductive layer in the pressure sensor as described above, and the signal acquisition module being used to collect the electrical signal output by the pressure sensor as described above.

[0098] In this embodiment, the signal acquisition module can be any circuit that can acquire analog signals and convert them into digital signals. Those skilled in the art can determine the specific circuit structure of the signal acquisition module according to actual needs, and no further details will be given here.

[0099] It should be noted that the pressure sensor manufacturing method and the pulse measurement device described above are similar to those described in the aforementioned pressure sensor embodiment, and have similar beneficial effects as the pressure sensor. For technical details not disclosed in the pressure sensor manufacturing method and pulse measurement device embodiments of this embodiment, please refer to the description of the pressure sensor embodiment of the present invention for an understanding.

[0100] In summary, the present invention provides a pressure sensor, a preparation method, and a pulse measurement device, which have the following beneficial effects:

[0101] When detecting pressure, the force-applying object acts directly on the protrusion. Since the contact area between the force-applying object and the protrusion is smaller than the contact area between the force-applying object and a planar layer, the setting of the protrusion reduces the force-bearing area of ​​the pressure sensor when the force-applying object acts on the pressure sensor, increases the pressure, and ensures the contact area between the first friction layer and the second friction layer even when the force is weak, thereby lowering the detection threshold of the pressure sensor. At the same time, the resistance generated by the air in the second channel in the insulating spacer layer to the first friction layer is balanced through the first channel, thereby improving the response capability of the pressure sensor.

[0102] It is understandable that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, all of which fall within the scope of protection of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of coverage of the claims of the present invention.

Claims

1. A pressure sensor, characterized in that: include: a first substrate layer; a first conductive layer provided on the lower surface of the first substrate layer; as well as a first friction layer disposed in contact with a lower surface of the first conductive layer; a protrusion provided on the upper surface of the first substrate layer, configured to contact a force-applying object and transmit external force to the first friction layer; a second substrate layer; a second conductive layer provided on the upper surface of the second substrate layer; a second friction layer disposed in contact with the upper surface of the second conductive layer; an insulating spacer layer disposed between the first friction layer and the second friction layer, the insulating spacer layer being provided with a first channel and a second channel penetrating the insulating spacer layer, the second channel being in communication with the exterior of the pressure sensor via the first channel, the first channel being used to balance the air pressure in the second channel with the air pressure outside the pressure sensor; The second friction layer and the first friction layer are made of triboelectric materials with opposite electrical properties. Under the action of an external force, at least a portion of the surface of the first friction layer contacts a portion of the surface of the second friction layer through the second channel. When the external force disappears, the first friction layer and the second friction layer separate. The area where the protrusion contacts the force-applying object is smaller than the area where the force-applying object directly contacts a planar layer.

2. The pressure sensor according to claim 1, wherein The protrusions include: protrusions with a cross-shaped structure.

3. The pressure sensor according to claim 1 or 2, characterized in that The first friction layer comprises: a polydimethylsiloxane film with a smooth surface; The second friction layer includes a fluorinated ethylene propylene film with a smooth surface.

4. The pressure sensor according to claim 1, wherein The first substrate layer and the second substrate layer are both made of polyethylene terephthalate film.

5. The pressure sensor according to claim 1, wherein The insulating spacer layer includes: a plurality of stacked polyimide double-sided adhesive tapes.

6. The pressure sensor according to claim 5, characterized in that The thickness of the insulating spacer layer ranges from 0.4 mm to 0.8 mm.

7. The pressure sensor according to claim 5 or 6, characterized in that: The first channels are respectively provided on both sides of the second channel, and the first channels are arranged opposite to each other.

8. The pressure sensor according to claim 1, wherein The upper surface of the first conductive layer and the lower surface of the first conductive layer are respectively coated with copper paste; The upper surface of the second conductive layer and the lower surface of the second conductive layer are respectively coated with copper paste.

9. A method for preparing a pressure sensor according to any one of claims 1 to 8, characterized in that: include: Providing a protrusion, a first friction layer, a first conductive layer, a first substrate layer, a second friction layer, a second conductive layer, a second substrate layer and an insulating spacer layer; Adhere the first friction layer to the lower surface of the first conductive layer; Adhere the first substrate layer to the upper surface of the first conductive layer; adhering the second friction layer to the upper surface of the second conductive layer; pasting the second substrate layer on the lower surface of the second conductive layer; Adhere the protrusion to the upper surface of the first substrate layer; Adhere the lower surface of the first friction layer to the upper surface of the insulating spacer layer; The upper surface of the second friction layer is adhered to the lower surface of the insulating spacer layer.

10. A pulse measuring device, characterized in that: include: A shell, a signal acquisition module arranged in the shell, and a pressure sensor as described in any one of claims 1 to 8, wherein the signal acquisition module is electrically connected to the first conductive layer and the second conductive layer in the pressure sensor as described in any one of claims 1 to 8, and the signal acquisition module is used to collect the electrical signal output by the pressure sensor as described in any one of claims 1 to 8.

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