Three-dimensional force sensing array sensor based on piezoelectric elements and pressure calculation method

Abstract

This invention discloses a three-dimensional force sensing array sensor based on piezoelectric elements and a pressure calculation method. The three-dimensional force sensing array sensor based on piezoelectric elements includes multiple sensing units, each of which includes a silicon substrate, electrodes, a conductive layer, piezoelectric fiber pillars, and an insulating layer. There are four electrodes connected to the silicon substrate and located on one side of the substrate. The conductive layer is located on the side of the electrodes away from the silicon substrate and is connected to the negative electrode. There are four piezoelectric fiber pillars, electrically connected to the electrodes and the conductive layer, perpendicular to the electrodes and the conductive layer, and located near the edge of the conductive layer. The insulating layer is connected to the conductive layer and located on the side of the conductive layer away from the four piezoelectric fiber pillars. The multiple sensing units are arranged in an array along the X and Y axes of a Cartesian coordinate system established with the center point of the conductive layer as the origin. This achieves high-resolution, high-precision three-dimensional sensing of a large area of ​​three-dimensional force space, with a simple structure and high sensitivity.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a three-dimensional force sensing array sensor based on piezoelectric elements and a pressure calculation method. Background Technology

[0002] With the development of science and technology and the improvement of application technology, higher requirements have been placed on the resolution and sensitivity of sensors. To address this issue, experts both domestically and internationally have conducted extensive research, resulting in many new types of sensors. Among them, piezoelectric sensors are lightweight, reliable, simple in structure, and highly sensitive, making them highly valuable in practical applications.

[0003] Currently, sensors can be broadly classified into six types based on their sensing materials and sensing mechanisms: mechanical, piezoresistive, capacitive, piezoelectric, piezomagnetic, and photoelectric. Mechanical sensors rely on external forces to induce mechanical displacement, but their spatial resolution is limited and their structure is complex. Piezoresistive sensors utilize the piezoresistive effect of single-crystal silicon and integrated circuit technology, offering excellent load capacity and a wide dynamic range, but also suffer from hysteresis, the need to optimize the elastic material properties, and monotonic nonlinear response. Capacitive sensors operate on the principle that the deformation of the elastic dielectric layer between two parallel plates under pressure results in a change in capacitance, offering advantages such as a wide dynamic range, linear response, and robustness, but also disadvantages such as susceptibility to temperature-dependent dielectric properties and noise interference. Piezoelectric sensors use piezoelectric materials as their sensing elements; when these materials are subjected to external forces, their surface... A charge is generated, and after passing through a charge amplifier, measuring circuit, and impedance transformation, it is converted into an electrical output proportional to the applied external force. It has many advantages: light weight, reliable operation, simple structure, high signal-to-noise ratio, high sensitivity, and wide signal bandwidth, etc. Piezomagnetic sensors convert changes in force into changes in the permeability of the sensor's magnetic core and output an electrical signal. They have the advantages of high output power, strong signal, and simple structure, but are susceptible to scattering and noise. Photoelectric sensors use the deformation of an elastic body to modulate light waves, converting pressure into a light image. They have the advantages of high resolution, no electrical interference, and signal processing circuits that can be located away from the sensor, but their performance is highly dependent on the elastic body and exhibits hysteresis.

[0004] A piezoelectric sensor is a self-generating sensor that utilizes the piezoelectric effect of certain dielectrics. Under external force, an electric charge is generated on the surface of the dielectric, thus achieving the electrical measurement of non-electrical quantities. Piezoelectric sensing elements are force-sensitive elements that can measure physical quantities such as dynamic force, dynamic pressure, and vibration acceleration. Piezoelectric sensors are characterized by their small size, light weight, high frequency response, and high signal-to-noise ratio. Because they have no moving parts, they are robust in structure and exhibit high reliability and stability.

[0005] However, existing piezoelectric sensors have low spatial resolution and low sensitivity for local force signals. Summary of the Invention

[0006] The purpose of this invention is to provide a three-dimensional force sensing array sensor based on piezoelectric units and a pressure calculation method, which realizes three-dimensional calculation of local weak force signals, and obtains accurate three-dimensional force sensing with high spatial resolution over a large area. It has the characteristics of high spatial resolution and high sensitivity of local force signals.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a three-dimensional force sensing array sensor based on piezoelectric units, comprising multiple sensing units. Each sensing unit includes a silicon substrate, electrodes, a conductive layer, piezoelectric fiber pillars, and an insulating layer. The number of electrodes is four, and the four electrodes are connected to the silicon substrate and located on one side of the silicon substrate. The conductive layer is located on the side of the electrodes away from the silicon substrate and is connected to the negative electrode. The number of piezoelectric fiber pillars is four, and the four piezoelectric fiber pillars are electrically connected to the four electrodes and the conductive layer, perpendicular to the electrodes and the conductive layer, and located on the side near the edge of the conductive layer. The insulating layer is connected to the conductive layer and located on the side of the conductive layer away from the four piezoelectric fiber pillars. The multiple sensing units are arranged in an array along the X and Y axes of a Cartesian coordinate system established with the center point of the conductive layer as the origin.

[0008] The piezoelectric fiber column has a height of 10-20 mm and a diameter of 0.1-0.2 mm.

[0009] The center points of the four piezoelectric fiber pillars are all aligned with the center point of the conductive layer.

[0010] The conductive layer and the insulating layer both have a square cross-sectional area with a side length of 10 mm. The conductive layer has a thickness of 0.5 mm, and the insulating layer has a thickness of 0.1 mm.

[0011] The silicon substrate has a square cross-sectional area with a side length of 10 mm and a thickness of 0.5 mm.

[0012] The electrode has a circular cross-sectional area, a diameter of 2 mm, and a thickness of 0.2 mm. The center points of the four piezoelectric fiber pillars are located at the center points of the four electrodes, respectively.

[0013] Secondly, the present invention provides a pressure calculation method for a three-dimensional force sensing array sensor based on piezoelectric elements, comprising:

[0014] A coordinate system is established with the center of the conductive layer as the origin, the surface of the conductive layer away from the insulating layer as the XOY plane, and the direction parallel to the piezoelectric fiber column as the Y direction.

[0015] Based on the voltage or axial strain characteristics of the four piezoelectric fiber columns subjected to pressure along the X, Y, and Z axes respectively, the pressure in any direction can be calculated.

[0016] This invention discloses a three-dimensional force sensing array sensor and pressure calculation method based on piezoelectric elements. The sensor comprises multiple sensing units arranged in an array along the X and Y axes of a Cartesian coordinate system established with the center point of the conductive layer as the origin. Each sensing unit includes a silicon substrate, electrodes, a conductive layer, piezoelectric fiber pillars, and an insulating layer. The electrodes are connected to the silicon substrate and located on one side of the substrate. The conductive layer is located on the side of the electrodes away from the silicon substrate and is connected to the negative electrode. There are four piezoelectric fiber pillars, one for each electrode, electrically connected to the four electrodes and the conductive layer, perpendicular to the electrodes and the conductive layer, and located near the edge of the conductive layer. The insulating layer is connected to the conductive layer and located on the side of the conductive layer away from the four piezoelectric fiber pillars. This four-beam piezoelectric fiber structure enables omnidirectional pressure detection and possesses high sensitivity, allowing for accurate determination of the direction and magnitude of extremely small forces. It exhibits high spatial resolution and high sensitivity sensing characteristics for localized force signals. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the three-dimensional force sensing array sensor based on piezoelectric units according to the present invention;

[0019] Figure 2 This is a schematic diagram of the sensing unit of the present invention;

[0020] Figure 3 This is a flowchart illustrating the pressure calculation method of the three-dimensional force sensing array sensor based on piezoelectric units according to the present invention.

[0021] In the figure: 100-Three-dimensional force sensing array sensor based on piezoelectric unit, 1-Sensing unit, 11-Silicon substrate, 12-Electrode, 13-Conductive layer, 14-Piezoelectric fiber column, 15-Insulating layer. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] Firstly, please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of the three-dimensional force sensing array sensor 100 based on piezoelectric units according to the present invention; please refer to [link / reference]. Figure 2 , Figure 2 This is a schematic diagram of the structure of the sensing unit 1 of the present invention. The present invention provides a three-dimensional force sensing array sensor 100 based on piezoelectric units, including multiple sensing units 1. Each sensing unit 1 includes a silicon substrate 11, electrodes 12, a conductive layer 13, piezoelectric fiber pillars 14, and an insulating layer 15. There are four electrodes 12 connected to the silicon substrate 11 and located on one side of the silicon substrate 11. The conductive layer 13 is located on the side of the electrodes 12 away from the silicon substrate 11 and is connected to the negative electrode. There are four piezoelectric fiber pillars 14, which are electrically connected to the four electrodes 12 and the conductive layer 13, and are perpendicular to the electrodes 12 and the conductive layer 13, and located on the side close to the edge of the conductive layer 13. The insulating layer 15 is connected to the conductive layer 13 and located on the side of the conductive layer 13 away from the four piezoelectric fiber pillars 14. The multiple sensing units 1 are arranged in an array along the X-axis and Y-axis of a rectangular coordinate system established with the center point of the conductive layer 13 as the origin.

[0025] In one embodiment, the silicon substrate 11 has a square cross-sectional area. Four independent electrodes 12 are fixed above the silicon substrate 11. Four piezoelectric fiber pillars 14 are parallel and electrically connected to the conductive layer 13. The conductive layer 13 is connected to the negative electrode by a wire, meaning the four piezoelectric fiber pillars 14 share a common negative electrode. The direction and magnitude of the three-dimensional force are obtained by calculating the positive electrode voltage. The lines connecting the center points of the four piezoelectric fiber pillars 14 to the center point of the conductive layer 13 are all equal, meaning they are composed of cylindrical fibers with equal angles to each other on their central axes. Each fiber has a diameter of 0.1-0.2 mm and a height of 10-20 mm. The four piezoelectric fiber pillars 14 are located on one side near the edge of the conductive layer 13. The conductive layer 13 and the insulating layer 15 both have a square cross-sectional area with a side length of 10 mm. The conductive layer 13 has a thickness of 0.5 mm, and the insulating layer 15 has a thickness of 0.1 mm.

[0026] In another embodiment, four independent electrodes 12 are fixed above the silicon substrate 11. Four piezoelectric fiber pillars 14 are parallel and electrically connected to the conductive layer 13. The conductive layer 13 is connected to the negative terminal of a wire, meaning the four piezoelectric fiber pillars 14 share a common negative terminal. The direction and magnitude of the three-dimensional force are obtained by calculating the positive electrode voltage. The lines connecting the center points of the four piezoelectric fiber pillars 14 to the center point of the conductive layer 13 are all equal, meaning they are composed of cylindrical fibers with equidistant central axes. Each fiber has a diameter of 0.1-0.2 mm and a height of 10-20 mm. The four piezoelectric fiber pillars 14 are located on the side closest to the edge of the conductive layer 13. The silicon substrate 11 has a square cross-sectional area with a side length of 10 mm and a thickness of 0.5 mm. The electrodes 12 have a circular cross-sectional area with a diameter of 2 mm and a thickness of 0.2 mm. The center points of the four piezoelectric fiber pillars 14 are respectively located at the center points of the four electrodes 12.

[0027] Secondly, please refer to Figure 3 , Figure 3 This is a flowchart illustrating the pressure calculation method of the three-dimensional force sensing array sensor based on piezoelectric elements according to the present invention; the present invention provides a pressure calculation method of the three-dimensional force sensing array sensor based on piezoelectric elements, comprising:

[0028] S101. Establish a coordinate system with the center of the conductive layer 13 as the origin, the surface of the conductive layer 13 away from the insulating layer 15 as the XOY plane, and the direction parallel to the piezoelectric fiber column 14 as the Y direction.

[0029] In this embodiment of the invention, the four piezoelectric fiber pillars 14 are perpendicular to the conductive layer 13 and parallel to the Z-axis. The side of the four piezoelectric fiber pillars 14 away from the conductive layer 13 is the vertex. The four piezoelectric fiber pillars 14 are fiber pillar a, fiber pillar b, fiber pillar c, and fiber pillar d, respectively. The coordinates of the vertex of fiber pillar a are (-4.5, 4.5, 20), the coordinates of fiber pillar b are (4.5, 4.5, 20), the coordinates of fiber pillar c are (-4.5, -4.5, 20), and the coordinates of fiber pillar d are (4.5, -4.5, 20).

[0030] S102. Based on the voltage or axial strain characteristics of the four piezoelectric fiber columns 14 when subjected to pressure along the X, Y, and Z axes respectively, the pressure in any direction is calculated.

[0031] In this embodiment of the invention, the pressure loads along the X, Y, and Z axes are of the same magnitude. The output voltage of each fiber obtained under each load is a voltage ratio. The force application point is at the center of the upper surface of the insulating layer 15. Compared to the Z-axis pressure load, the four piezoelectric fiber pillars 14 are more sensitive to the X and Y-axis pressure loads. a U b U c U d The voltage value is obtained by sensing arbitrary pressure on the four piezoelectric fiber columns 14. Simultaneously, regardless of whether the pressure load is applied along the X-axis or Y-axis, U... ax +U bx +U cx +U dx =U ay +U by +U cy +U dy =0, meaning the sum of the voltages of the four piezoelectric fibers in the XOY plane is 0. When subjected to a load along the Z-axis, U az =U bz =U cz =U dz .

[0032] Voltage in the Z direction: After removing the voltage in the Z direction, the voltages of fiber column a, fiber column b, fiber column c, and fiber column d in the XOY plane are respectively: U a -U z U b -U z U c -U z U d -U z ;

[0033] Voltage in the X direction:

[0034] U x =-(Ua -U z cos45°+(U b -U z cos45°-(U c -U z cos45°+(U d -U z cos45°;

[0035] Right now:

[0036] Voltage in the Y direction:

[0037] U y =(U a -U z sin45°+(U b -U z sin45°-(U c -U z sin45°-(U d -U z sin45°;

[0038] Right now:

[0039] A x A y A Z Let X, Y, and Z be the pressure load components in the X, Y, and Z directions, respectively.

[0040] A x :A y :

[0041] To verify the accuracy and precision of the above calculations, the following method was used: Pressure loads of the same magnitude but different directions were applied to the four piezoelectric fiber pillars 14. The point of application of the force was the center of the upper surface of the insulating layer 15. Through multiple experiments, the sum of the axial strains of the four piezoelectric fiber pillars 14 was calculated to determine the vector direction and magnitude of the pressure. The vector direction and magnitude of the pressure were also calculated based on the output voltage of the four piezoelectric fiber pillars. By calculating the proportional relationship of the axial strains of each axis under different load directions, the synthesized vector magnitude was consistently 0.875 × 10⁻⁶. -5 Maximum error 1×10 -8 Its axial strain sensitivity is:

[0042]

[0043] By calculating the proportional relationship of voltages along each axis under loads in different directions, the magnitude of the synthesized vector is 1.56 × 10⁻⁶. -13 V, maximum error 1×10 -5 The voltage sensitivity is:

[0044]

[0045] The working process is as follows: When external pressure is applied to the insulating layer 15 of the pressure sensor, it causes the four piezoelectric fiber pillars 14 to deform. Due to the piezoelectric effect of this material, an excitation phenomenon occurs inside. The piezoelectric fibers are polarized along the axial direction, and the fibers are amplified and measured by a charge amplifier and a measuring circuit. The change in the measurement result indirectly reflects the change in external pressure, and then the magnitude of the pressure is calculated.

[0046] This invention discloses a three-dimensional force sensing array sensor based on piezoelectric units. The sensor unit 1 comprises multiple sensing units 1 arranged in an array along the X and Y axes of a Cartesian coordinate system established with the center point of the conductive layer 13 as the origin. Each sensing unit 1 includes a silicon substrate 11, electrodes 12, a conductive layer 13, piezoelectric fiber pillars 14, and an insulating layer 15. The electrodes 12 are connected to the silicon substrate 11 and located on one side of the silicon substrate 11. The conductive layer 13 is located on the side of the electrodes 12 away from the silicon substrate 11 and is connected to the negative electrode. There are four piezoelectric fiber pillars 14, and four electrodes 12. Each of the four piezoelectric fiber pillars 14 is electrically connected to one of the four electrodes 12 and one of the four conductive layers 13, and is perpendicular to the electrodes 12 and the conductive layer 13, located near the edge of the conductive layer 13. The insulating layer 15 is connected to the conductive layer 13 and is located on the side of the conductive layer 13 away from the four piezoelectric fiber pillars 14. The device employs a four-beam piezoelectric fiber structure to achieve omnidirectional pressure detection and possesses high sensitivity. It can accurately determine the direction and magnitude of extremely small forces and has the characteristics of high spatial resolution and high sensitivity for local force signals.

[0047] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A three-dimensional force sensing array sensor based on piezoelectric unit, characterized in that, a plurality of sensing units are included, each of the sensing units comprising a silicon substrate, an electrode, a conductive layer, four piezoelectric fiber columns and an insulating layer, the electrode being connected to the silicon substrate and located on one side of the silicon substrate, the conductive layer being located on the side of the electrode away from the silicon substrate and connected to a negative electrode, the number of the piezoelectric fiber columns and the electrode being four, the four piezoelectric fiber columns being electrically connected to the four electrodes and the conductive layer and being perpendicular to the electrodes and the conductive layer and located on the side close to the edge of the conductive layer, the insulating layer being connected to the conductive layer and located on the side of the conductive layer away from the four piezoelectric fiber columns, the plurality of sensing units being arranged in an array along the X and Y axes of a rectangular coordinate system with the center point of the conductive layer as the origin; the height of the piezoelectric fiber column is 10-20 mm, and the diameter is 0.1-0.2 mm; the center points of the four piezoelectric fiber columns and the center point of the conductive layer are equal; the cross-sectional area of the conductive layer and the insulating layer is a square, and the side length is 10 mm, the thickness of the conductive layer is 0.5 mm, and the thickness of the insulating layer is 0.1 mm; when external pressure is applied to the insulating layer of the pressure sensor, the four piezoelectric fiber columns are deformed, and the piezoelectric fiber is polarized along the axial direction. 2.The three-dimensional force sensing array sensor based on piezoelectric unit according to claim 1, characterized in that, the cross-sectional area of the silicon substrate is a square, and the side length is 10 mm, and the thickness of the silicon substrate is 0.5 mm. 3.The three-dimensional force sensing array sensor based on piezoelectric unit according to claim 2, characterized in that, the cross-sectional area of the electrode is a circle, the diameter is 2 mm, the thickness is 0.2 mm, and the center points of the four piezoelectric fiber columns are located at the center points of the four electrodes respectively.

4. A method of pressure calculation for a three-dimensional force sensing array sensor based on piezoelectric elements as claimed in any one of claims 1 to 3, characterized in that, including: a coordinate system is established with the center of the conductive layer as the origin, the face of the conductive layer away from the insulating layer as the XOY plane, and the direction parallel to the piezoelectric fiber column as the Y direction; the pressure in any direction is calculated according to the voltage or axial strain law of the four piezoelectric fiber columns under the pressure along the X, Y and Z axes respectively.

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