A composite mechanical sensor

Abstract

The present invention discloses a novel composite mechanical sensor, belonging to the field of mechanical sensors. The novel composite mechanical sensor comprises a flexible sensing layer for relative motion with a sensed object, an electrode sensing layer, a piezoelectric material layer, and a signal processing board for generating electrical signals. The electrode sensing layer is located on one side of the flexible sensing layer, with a gap between the flexible sensing layer and the electrode sensing layer. The piezoelectric material layer is located within the gap between the flexible sensing layer and the electrode sensing layer. The novel composite mechanical sensor not only combines piezoelectric and triboelectric power generation technologies to generate electricity simultaneously, but also can sense the motion state of the sensed object in real time, preventing distortion of collected data.

Description

Technical Field

[0001] The present invention relates to the field of mechanical sensors, and in particular to a composite mechanical sensor. Background Art

[0002] Existing mechanical sensors refer to devices that convert the magnitude of force into related electrical signals. Mechanical sensors are usually composed of force-sensitive elements, conversion elements and circuit parts. Since the conversion elements and circuit parts usually require electrical drive, existing mechanical sensors often need to be connected with wires or provided with batteries. Both methods have great limitations. The use of batteries not only affects the service life, but also easily leads to poor measurement accuracy due to the consumption of electrical energy. The use of guided power supply obviously greatly limits the use scenarios of mechanical sensors. For example, it is impossible to detect the surface arterial pressure of a running person.

[0003] Chinese patent publication number CN108429482B discloses a micromechanical sensor based on a triboelectric nanogenerator. The sensor comprises a triboelectric nanogenerator for measuring mechanical signals, a data transmission device connected to the triboelectric nanogenerator via an analog-to-digital conversion system, and a display device connected to the data transmission device for displaying the measured data. This composite mechanical sensor utilizes only the triboelectric nanogenerator for power generation, resulting in limited power generation and difficulty converting complex electrical signals. Furthermore, the sensor is insensitive to the sensed object. Summary of the Invention

[0004] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to propose a composite mechanical sensor, which not only combines piezoelectric and friction power generation technologies to generate electricity simultaneously, but also can sense the motion state of the sensed object in real time to prevent distortion of information collection data.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] The present invention provides a composite mechanical sensor, comprising a flexible sensing layer for relative motion with a sensed object, an electrode sensing layer, a piezoelectric material layer, and a signal processing board for generating an electrical signal. The electrode sensing layer is located on one side of the flexible sensing layer, with a gap between the flexible sensing layer and the electrode sensing layer. The piezoelectric material layer is located in the gap between the flexible sensing layer and the electrode sensing layer. When the flexible sensing layer moves normal to the sensed object, the flexible sensing layer squeezes the piezoelectric material layer, causing the piezoelectric material layer to generate a first type of electrical signal. When the flexible sensing layer moves tangentially to the sensed object, the flexible sensing layer generates induced charges, which in turn cause the electrode sensing layer to generate induced charges, causing the electrode sensing layer to generate a second type of electrical signal. The signal processing board rectifies the first and second type of electrical signals to form a power supply that supplies power to the signal processing board. The signal processing board outputs an electrical signal based on the waveform characteristics of the first and second type of electrical signals.

[0007] A further technical feature of the present invention is that the signal processing board includes a first FPCB circuit, and a rectifier circuit is provided on the first FPCB circuit. The first type of electrical signal and the second type of electrical signal are rectified by the rectifier circuit and output as direct current to power the signal processing board.

[0008] A further technical feature of the present invention is that the signal processing board also includes a second FPCB circuit, the piezoelectric material layer is attached to the second FPCB circuit, and the first FPCB circuit (14) and the second FPCB circuit collect the potential difference between the upper and lower surfaces of the piezoelectric material layer and convert it into a first type of electrical signal.

[0009] A further technical feature of the present invention is that the flexible sensing layer is made of PDMS material, the piezoelectric material layer is made of PVDF material, the first FPCB circuit and the second FPCB circuit are attached to the piezoelectric material layer from the upper and lower sides of the piezoelectric material layer, and the first FPCB circuit and the second FPCB circuit are used as conductive layers of the piezoelectric material layer.

[0010] A further technical feature of the present invention is that the thickness of the flexible sensing layer is 0.5 to 2 mm, and the ratio of the monomer component to the crosslinking agent component of the PDMS material is (20 to 30):1.

[0011] A further technical feature of the present invention is that an etched microstructure is provided on the outer surface of the flexible sensing layer, wherein the etched microstructure is composed of directionally arranged micropillars, and the distance between two adjacent micropillars is 5 to 10 nm.

[0012] A further technical feature of the present invention is that it further comprises a first frame for fixing the flexible sensing layer, and the flexible sensing layer is fixed in the middle of the first frame.

[0013] A further technical feature of the present invention is that it also includes a second frame with a cavity in the middle, the signal processing board, the piezoelectric material layer, and the electrode sensing layer are fixed in the cavity of the second frame in sequence, and the first frame is fixedly connected to the second frame.

[0014] A further technical feature of the present invention is that it also includes an energy storage device, and the signal processing board rectifies the first type of electrical signal and the second type of electrical signal to generate electricity to charge the energy storage device, and the energy storage device is electrically connected to the signal processing board to supply power to the signal processing board.

[0015] A further technical feature of the present invention is that an AI chip is provided on the signal processing board, and the AI ​​chip learns the waveform characteristics of the first type of electrical signal and the second type of electrical signal, and outputs the electrical signal based on the learning results.

[0016] The beneficial effects of the present invention are:

[0017] The composite mechanical sensor provided by the present invention is provided with a flexible sensing layer, an electrode sensing layer, a piezoelectric material layer, and a signal processing board for generating electrical signals. When the flexible sensing layer moves normally relative to the sensed object, the flexible sensing layer squeezes the piezoelectric material layer to generate a first type of electrical signal. When the flexible sensing layer moves tangentially relative to the sensed object, the induced charge generated by the flexible sensing layer causes the electrode sensing layer to generate an induced charge to generate a second type of electrical signal, thereby enabling the above-mentioned sensor to spontaneously generate two types of electrical signals. In addition, the flexible sensing layer provided by the present application can be well attached to the sensed object, and can more directly sense the motion state of the sensed object. The first type of electrical signal and the second type of electrical signal can also be used as electrical signals for the signal processing board to analyze the electrical characteristics, thereby realizing direct electrical analysis of the collected amount without the need for the force-sensitive element and conversion element of the traditional mechanical sensor, thereby effectively preventing distortion of the information collection data. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of a composite mechanical sensor provided in a specific embodiment of the present invention;

[0019] Figure 2 It is an experimental effect diagram of the composite mechanical sensor provided in a specific embodiment of the present invention.

[0020] In the picture:

[0021] 11. Flexible sensing layer; 12. Electrode sensing layer; 13. Piezoelectric material layer; 14. First FPCB circuit; 15. Rectifier circuit; 16. Second FPCB circuit; 17. First frame; 18. Second frame; 19. Energy storage device; 141. AI chip; 20. Screws. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0023] Example 1

[0024] like Figures 1 to 2As shown, the composite force sensor provided in this embodiment includes a flexible sensing layer 11 for relative motion with a sensed object, an electrode sensing layer 12, a piezoelectric material layer 13, and a signal processing board for generating electrical signals. The flexible sensing layer 11 is made of PDMS material, the piezoelectric material layer 13 is configured as a piezoelectric film made of PVDF material, and the electrode sensing layer 12 is made of a Cu sheet. The electrode sensing layer 12 is located on one side of the flexible sensing layer 11, with a gap between the flexible sensing layer 11 and the electrode sensing layer 12. The piezoelectric material layer 13 is located in the gap between the flexible sensing layer 11 and the electrode sensing layer 12. The upper and lower surfaces of the flexible sensing layer 11, the electrode sensing layer 12, and the piezoelectric material layer 13 are sequentially connected. The flexible sensing layer 11 moves normally relative to the sensed object. That is, when the flexible sensing layer 11 is squeezed by the sensed object, the flexible sensing layer 11 will mainly generate pressure along the normal motion of the sensed object, that is, pressure perpendicular to the outer surface of the sensed object. For example, if the flexible sensing layer 11 is placed on the outer surface of an arm at the human artery, it will be affected by the normal motion generated by the arterial pulsation. When the flexible sensing layer 11 moves normally relative to the sensed object, it squeezes the piezoelectric material layer 13, generating a potential difference between the first FPCB circuit 14 and the second FPCB circuit 1, thereby forming a first type of electrical signal. When the flexible sensing layer 11 moves tangentially relative to the sensed object, that is, when it performs horizontal friction-like motion relative to the outside of the sensed object, the induced charge generated by the flexible sensing layer 11 causes the electrode sensing layer 12 to generate induced charge, thereby forming a single-electrode friction nanogenerator. The electrode sensing layer 12 generates a second type of electrical signal due to the induction. The signal processing board rectifies the first and second type of electrical signals to form a power supply that powers the signal processing board. The signal processing board outputs electrical signals based on the waveform characteristics of the first and second type of electrical signals. Therefore, the composite mechanical sensor provided in this embodiment can spontaneously generate two types of electrical signals. In addition, the flexible sensing layer 11 provided in the present application can be well attached to the sensed object, and can sense the movement state of the sensed object more directly. The first type of electrical signal and the second type of electrical signal can also be used as electrical signals at the same time for the signal processing board to analyze the electrical characteristics, thereby realizing direct electrical analysis of the collected quantity without the need for force-sensitive elements and conversion elements of traditional mechanical sensors, thereby effectively preventing distortion of information collection data.

[0025] In a further technical solution, the signal processing board is configured as a first FPCB circuit 14, which is equipped with a rectifier circuit 15. The first and second electrical signals are rectified by rectifier circuit 15 and output as direct current to power the signal processing board. Rectifier circuit 15 converts the first and second electrical signals into direct current to power the electronic components on first and second FPCB circuits 14, 16. The use of first FPCB circuit 14 is primarily due to its ability to increase the distance between flexible sensing layer 11 and electrode sensing layer 12 and to facilitate a more direct application of external forces acting on flexible sensing layer 11 to piezoelectric material layer 13.

[0026] In order to more conveniently collect the first type of electrical signal generated by the piezoelectric material layer 13, the composite mechanical sensor provided in this embodiment further includes a second FPCB circuit 16. The piezoelectric material layer 13 is located on the second FPCB circuit 16. The second FPCB circuit 16 collects the potential difference between the upper and lower surfaces of the piezoelectric material layer 13 and converts it into a first type of electrical signal. Since the second FPCB circuit 16 is directly electrically connected to the upper and lower poles of the piezoelectric material layer 13, it can better collect the first type of electrical signal generated by the piezoelectric material layer 13.

[0027] Further preferably, the flexible sensing layer 11 is made of PDMS material, the piezoelectric material layer 13 is made of flexible PVDF material, the first FPCB circuit 14 and the second FPCB circuit 16 are adhered to the piezoelectric material layer 13 from the upper and lower sides of the piezoelectric material layer 13, and the first FPCB circuit 14 and the second FPCB circuit 16 serve as conductive layers of the piezoelectric material layer 13. The combination of these four materials can most effectively collect power generation and mechanical information related to electrical signals. The first FPCB circuit 14 and the second FPCB circuit 16 serve as the conductive layer of the piezoelectric material layer 13. They can be attached to the upper and lower sides of the piezoelectric material layer 13 to form two electrodes, and form a piezoelectric nanogenerator with the piezoelectric material layer 13. The first FPCB circuit 14 and the second FPCB circuit 16 are made of the same material, which can ensure that the piezoelectric material layer 13 produces uniform deformation and provide a relatively stable first-class electrical signal. This is because the Young's modulus of different materials often differs. Arranging the first FPCB circuit 14 and the second FPCB circuit 16 of the same material on both sides of the piezoelectric material layer 13 made of flexible PVDF material can effectively overcome the above-mentioned defects. Thus, attaching the first FPCB circuit 14 and the second FPCB circuit 16 to the piezoelectric material layer 13 from the upper and lower sides thereof has at least three advantages: 1. The first FPCB circuit 14 and the second FPCB circuit 16 can serve as an encapsulation for the piezoelectric material layer 13, protecting it; 2. The first FPCB circuit 14 and the second FPCB circuit 16 can also serve as the conductive layer of the piezoelectric nanogenerator; and 3. The first FPCB circuit 14 and the second FPCB circuit 16 themselves serve as carriers for circuits such as the rectifier circuit 15. This arrangement eliminates the need for additional circuit layers, significantly reducing the size of the composite mechanical sensor. The flexible sensing layer 11 must be in contact and separation with the object being sensed to achieve the most effective output. Therefore, placing it at the outermost edge of the composite mechanical sensor allows for direct contact with the object being sensed while also providing isolation between the electrode sensing layer 12 and sensing alternating current. There is no necessary requirement for the piezoelectric material layer 13 to be in direct contact with the sensed object, so it is disposed between the flexible sensing layer 11 and the electrode sensing layer 12 , which can both play an isolation role and be subjected to the pressure transmitted by the flexible sensing layer 11 .Further preferably, the thickness of the flexible sensing layer 11 is 0.5 to 2 mm. Under this thickness condition, the flexible sensing layer 11 can effectively ensure that the piezoelectric material layer 13 has good sensitivity to pressure, that is, the piezoelectric nanogenerator has sufficient output, and can ensure that sufficient alternating current is generated between the flexible sensing layer 11 and the electrode sensing layer 12. Because the flexible sensing layer 11 is too thick, it will obviously reduce the sensitivity of the piezoelectric material layer 13 to pressure, and too thin will affect the power generation of the second type of electrical signal generated by the single-electrode friction nanogenerator. Therefore, a reasonable setting of the thickness of the flexible sensing layer 11 is conducive to ensuring the stability and strength of the output electrical signal of the composite mechanical sensor. Furthermore, preferably, the monomer component and cross-linking agent component ratio of the PDMS material is (20-30):1, and the monomer component is generally polydimethylsiloxane, etc. Reasonable control of the ratio between the monomer component and the cross-linking agent component will make the flexible sensing layer 11 moderately soft and hard, which can ensure the stable output of the single-electrode friction nanogenerator and ensure that the pressure exerted on the flexible sensing layer 11 can be effectively transmitted to the piezoelectric material layer 13, further ensuring the strength and stability of the piezoelectric signal. Further preferably, the outer surface of the flexible sensing layer 11 is provided with an etched microstructure, which is composed of micro-pillars arranged in an oriented manner, and the spacing between two adjacent micro-pillars is 5-10nm. The oriented micro-pillars can significantly enhance the friction effect of the outer surface of the flexible sensing layer 11, and can significantly enhance the output of the second type of electrical signal of the single-electrode friction nanogenerator and increase the amount of the second type of electrical signal output.

[0028] In order to encapsulate and fix the flexible sensing layer 11, the electrode sensing layer 12, the piezoelectric material layer 13, and the signal processing board for generating electrical signals, the composite mechanical sensor provided in this embodiment further includes a first frame 17 for fixing the flexible sensing layer 11. The flexible sensing layer 11 is fixed in the middle of the first frame 17. The first frame 17 can be used to install and fix the flexible sensing layer 11. Further preferably, the composite mechanical sensor provided in this embodiment further includes a second frame 18 having a cavity in the middle portion, the signal processing board, the piezoelectric material layer 13, and the electrode sensing layer 12 are fixed in the cavity of the second frame 18 in sequence, and the first frame 17 and the second frame 18 are fixedly connected so that the upper and lower surfaces of the flexible sensing layer 11, the electrode sensing layer 12, and the piezoelectric material layer 13 are in contact with each other in sequence, that is, the upper and lower surfaces of the flexible sensing layer 11, the electrode sensing layer 12, and the piezoelectric material layer 13 are in direct contact, and at the same time, the first FPCB circuit 14 is located between the flexible sensing layer 11 and the piezoelectric material layer 13, the upper surface of the first FPCB circuit 14 is against the flexible sensing layer 11, and the lower surface of the first FPCB circuit 14 is against the piezoelectric material layer 13, that is, from the flexible sensing layer 11 to the piezoelectric material layer 13, they can quickly respond to the motion state of the sensed object, thereby improving the power generation sensitivity of the piezoelectric material layer 13. The purpose of this design is to enable the piezoelectric material layer 13 to more directly sense the motion state of the sensed object, thereby further preventing distortion of the information collected. At the same time, because the upper and lower poles of the piezoelectric material layer 13 are electrically isolated, the flexible sensing layer 11 and the electrode sensing layer 12 are also electrically isolated, thereby preventing the induced charge from being neutralized. Further preferably, the first frame 17 and the second frame 18 are fixedly connected by a snap connection or a screw connection. When the screw connection is used, four screw holes are provided on the first frame 17, and four screws 20 are screwed into the four blind holes on the second frame 18 after passing through their respective screw holes.

[0029] In a further technical solution, the composite force sensor provided in this embodiment also includes an energy storage device 19. The signal processing board controls the first and second electrical signals, rectified to generate electricity to charge the energy storage device 19. The energy storage device 19 is electrically connected to the signal processing board to provide power to the signal processing board. The energy storage device 19 not only stabilizes the DC power supplied by the first and second FPCB circuits 14 and 16 but also collects excess electricity generated by the vigorous movement of the sensed object to meet power generation needs when the sensed object is inactive or experiencing minimal movement, thus ensuring a stable power supply for the sensor.

[0030] In order to improve the accuracy of the electrical signal output by the composite mechanical sensor, an AI chip 141 is further provided on the signal processing board. The waveform characteristics of the first type of electrical signal and the second type of electrical signal are learned by the AI ​​chip 141, and the electrical signal is output based on the learning result. The output electrical signal is usually converted into a pressure signal or a pulse signal based on the voltage waveform and current waveform changes of the first type of electrical signal and the second type of electrical signal, and the detection accuracy is improved through the AI ​​algorithm built into the AI ​​chip 141.

[0031] The present invention is described through preferred embodiments. Those skilled in the art will appreciate that various modifications or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. The present invention is not limited to the specific embodiments disclosed herein; other embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A composite mechanical sensor, characterized in that: include: A flexible sensing layer (11) for relative motion with a sensed object; an electrode sensing layer (12), the electrode sensing layer (12) being located on one side of the flexible sensing layer (11), with a gap being left between the flexible sensing layer (11) and the electrode sensing layer (12); a piezoelectric material layer (13), the piezoelectric material layer (13) being located in a gap between the flexible sensing layer (11) and the electrode sensing layer (12); A signal processing board for generating an electric signal, wherein when the flexible sensing layer (11) moves in a normal direction relative to the sensed object, the flexible sensing layer (11) squeezes the piezoelectric material layer (13), and the piezoelectric material layer (13) generates a first type of electric signal; when the flexible sensing layer (11) moves in a tangential direction relative to the sensed object, the flexible sensing layer (11) generates induced charges, which causes the electrode sensing layer (12) to generate induced charges, and the electrode sensing layer (12) generates a second type of electric signal; the signal processing board supplies power to the signal processing board through a power supply formed after rectifying the first type of electric signal and the second type of electric signal; and the signal processing board outputs an electric signal according to the waveform characteristics of the first type of electric signal and the second type of electric signal; The signal processing board includes a first FPCB circuit (14); The signal processing board further includes a second FPCB circuit (16); The first FPCB circuit (14) and the second FPCB circuit (16) are attached to the piezoelectric material layer (13) from the upper and lower sides of the piezoelectric material layer (13), and the first FPCB circuit (14) and the second FPCB circuit (16) are used as conductive layers of the piezoelectric material layer (13).

2. The composite mechanical sensor according to claim 1, wherein: The first FPCB circuit (14) is provided with a rectifier circuit (15), and the first type of electrical signal and the second type of electrical signal are rectified by the rectifier circuit (15) and then output as direct current to power the signal processing board.

3. The composite mechanical sensor according to claim 2, wherein: The piezoelectric material layer (13) is attached to the second FPCB circuit (16), and the first FPCB circuit (14) and the second FPCB circuit (16) collect the potential difference between the upper and lower surfaces of the piezoelectric material layer (13) and convert it into a first type of electrical signal.

4. The composite mechanical sensor according to claim 3, wherein: The flexible sensing layer (11) is made of PDMS material; The piezoelectric material layer (13) is made of PVDF material.

5. The composite mechanical sensor according to claim 4, characterized in that: The thickness of the flexible sensing layer (11) is 0.5 to 2 mm; The distribution ratio of the monomer component to the crosslinking agent component of the PDMS material is (20-30):

1.

6. The composite mechanical sensor according to claim 1, 4 or 5, characterized in that: The outer surface of the flexible sensing layer (11) is provided with an etched microstructure; The etching microstructure consists of micro pillars arranged in a direction, and the distance between two adjacent micro pillars is 5 to 10 nm.

7. The composite mechanical sensor according to claim 1, wherein: It also includes a first frame (17) for fixing the flexible sensing layer (11); The flexible sensing layer (11) is fixed in the middle of the first frame (17).

8. The composite mechanical sensor according to claim 7, characterized in that: It also includes a second frame (18) with a cavity in the middle; The signal processing board, the piezoelectric material layer (13), and the electrode sensing layer (12) are fixed in sequence in the cavity of the second frame (18), and the first frame (17) and the second frame (18) are fixedly connected.

9. The composite mechanical sensor according to claim 1, wherein: Also included is an energy storage device (19); The signal processing board rectifies the first type of electrical signal and the second type of electrical signal to generate electricity to charge the energy storage device (19), and the energy storage device (19) is electrically connected to the signal processing board to supply power to the signal processing board.

10. The composite mechanical sensor according to claim 1, characterized in that: The signal processing board is provided with an AI chip (141), and the waveform characteristics of the first type of electrical signal and the second type of electrical signal are learned based on the AI ​​chip (141), and the electrical signal is output based on the learning result.

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