A differential force measuring parallel plate capacitor sensor structure

Abstract

The application relates to the technical field of sensors and discloses a differential type force measuring parallel plate capacitor sensor structure which comprises a cylinder body, a first electrode plate and a second electrode plate which are parallel to each other are arranged in the cylinder body, the first electrode plate is located above the second electrode plate, a third electrode plate is further arranged in the cylinder body and is parallel to the first electrode plate and the second electrode plate, a plurality of through holes are formed in the third electrode plate, a first dielectric layer is arranged between the first electrode plate and the third electrode plate, the first dielectric layer is made of flexible and stretchable material, a second dielectric layer is arranged between the second electrode plate and the third electrode plate, the second dielectric layer is a liquid with a dielectric constant greater than that of air, the first electrode plate moves towards the third electrode plate under external force, and the third electrode plate moves towards the second electrode plate under external force. The capacitor sensor structure can greatly improve the measurement sensitivity of the capacitive sensor.

Description

Technical Field

[0001] This invention relates to the field of capacitive sensor technology, and in particular to a differential force-measuring parallel plate capacitive sensor structure. Background Technology

[0002] Capacitive sensing is a technique based on capacitive coupling that can be used to detect any conductive medium other than air. A capacitive pressure sensor is a device that detects external pressure stimuli based on changes in the sensor's capacitance. The sensor consists of two closely spaced conductive electrode plates and an insulating dielectric layer between them. Sensitivity is a crucial performance indicator for capacitive flexible pressure sensors; high-sensitivity sensors often have shorter response times and better human-computer interaction capabilities. Currently, breakthroughs are still needed to improve the sensitivity of capacitive sensors, making it an important research topic. Summary of the Invention

[0003] This invention provides a differential force-measuring parallel plate capacitive sensor structure, which can significantly improve the measurement sensitivity of capacitive sensors.

[0004] This invention provides a differential force-measuring parallel plate capacitive sensor structure, comprising: a cylindrical body, wherein a first electrode plate and a second electrode plate are disposed inside the cylindrical body, the first electrode plate being located above the second electrode plate; characterized in that the cylindrical body further comprises:

[0005] The third electrode plate is located between the first electrode plate and the second electrode plate, and is parallel to the first electrode plate and the second electrode plate. The third electrode plate has multiple through holes.

[0006] A first dielectric layer is disposed between a first electrode plate and a third electrode plate, and the first dielectric layer is made of a flexible and stretchable material.

[0007] A second dielectric layer is disposed between the second electrode plate and the third electrode plate, wherein the second dielectric layer is a liquid with a dielectric constant greater than that of air;

[0008] When the first electrode plate is subjected to an external force, it moves toward the third electrode plate, and when the third electrode plate is subjected to an external force, it moves toward the second electrode plate.

[0009] Furthermore, the first dielectric layer is provided with regular holes or thin tubes.

[0010] Furthermore, the first dielectric layer is made of a material that does not wet the liquid.

[0011] Furthermore, the first electrode plate, the second electrode plate, and the third electrode plate are all metal electrode plates.

[0012] Furthermore, the first electrode plate and the third electrode plate are connected to electrode leads, and the second electrode plate and the third electrode plate are connected to electrode leads.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] When an external force is applied to the first electrode plate, the first dielectric layer is compressed, the distance between the first and third electrode plates decreases, the third electrode plate moves towards the second electrode plate, and a portion of the liquid in the second dielectric layer enters the holes or tubes in the first dielectric layer through the through-holes, causing the air in the original holes or tubes in the first dielectric layer to be replaced by liquid. According to the formula for calculating the dielectric constant, the dielectric constant has a large increment, and the capacitance value of the first parallel plate capacitor has a large increment.

[0015] In summary, the capacitive sensor structure provided by this invention can significantly improve the measurement sensitivity of capacitive sensors. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a differential force-measuring parallel plate capacitive sensor structure provided by the present invention.

[0017] Figure 2 This is a cross-sectional view of a first dielectric layer with a thin tube provided in an embodiment of the present invention.

[0018] Figure 3 This is a cross-sectional view of a liquid second dielectric layer provided in an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures:

[0020] 1-First electrode plate, 2-Third electrode plate, 3-Second electrode plate, 4-First dielectric layer, 5-Second dielectric layer, 6-Through hole, 7-Cylinder body. Detailed Implementation

[0021] The following is in conjunction with the appendix Figure 1-3 The present invention will be described in detail with respect to a specific embodiment, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this 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. Therefore, they should not be construed as limitations on this invention.

[0023] like Figure 1 and Figure 3 As shown in the figure, an embodiment of the present invention provides a differential force-measuring parallel plate capacitive sensor structure, comprising: a cylindrical body 7, wherein a first electrode plate 1 and a second electrode plate 3 are disposed inside the cylindrical body 7, the first electrode plate 1 being located above the second electrode plate 3; a third electrode plate 2 is also disposed inside the cylindrical body 7, located between the first electrode plate 1 and the second electrode plate 3, and parallel to the first electrode plate 1 and the second electrode plate 3, the third electrode plate 2 having a plurality of through holes 6; a first dielectric layer 4 disposed between the first electrode plate 1 and the third electrode plate 2, the first dielectric layer 4 being made of a flexible and stretchable material; and a second dielectric layer 5 disposed between the second electrode plate 3 and the third electrode plate 2, the second dielectric layer 5 being a liquid with a dielectric constant greater than that of air; the first electrode plate 1 moves toward the third electrode plate 2 when subjected to an external force, and the third electrode plate 2 moves toward the second electrode plate 3 when subjected to an external force.

[0024] The liquid can be pure water, the cylinder is made of insulating material, such as insulating rubber, and the first dielectric layer 4 is made of polydimethylsiloxane (PDMS).

[0025] Furthermore, such as Figure 2 As shown, the first dielectric layer 4 has regular holes or thin tubes.

[0026] Furthermore, the first dielectric layer 4 is made of a material that does not wet the liquid, to prevent the liquid from entering the first dielectric layer 4 through capillary action.

[0027] Furthermore, the first electrode plate 1, the second electrode plate 3, and the third electrode plate 2 are all metal electrode plates.

[0028] The first electrode plate 1, the second electrode plate 3, the third electrode plate 2, and the electrodes can all be made of silver.

[0029] Furthermore, the first electrode plate 1 and the third electrode plate 2 are connected to electrode leads, and the second electrode plate 3 and the third electrode plate 2 are connected to electrode leads.

[0030] Example 1

[0031] Fabrication: A first dielectric layer 4 with capillary tubes is prepared. A material that is non-wetting of the liquid can be selected to prepare the dielectric layer, preventing the liquid from entering the first dielectric layer 4 through capillary action. Metal plates with suitable conductivity are selected as the first electrode plate 1, the second electrode plate 3, and the third electrode plate 2 of the sensor. The third electrode plate 2 has uniform through holes, allowing the liquid below to flow into the first dielectric layer 4 with capillary tubes through the holes.

[0032] Example 2

[0033] Measurement: by Figure 1 It can be seen that the first electrode plate 1 and the third electrode plate 2 can form a parallel plate capacitor C1, and the third electrode plate 2 and the second electrode plate 3 can form a parallel plate capacitor C2. The first electrode plate 1 and the third electrode plate 2 are connected to electrodes to measure the capacitance value with the first dielectric layer 4 as the dielectric. The third electrode plate 2 and the second electrode plate 3 are connected to electrodes to measure the capacitance value with the liquid layer as the second dielectric layer 5. When an external force is applied to the first electrode plate 1, the first dielectric layer 4 is compressed, and simultaneously, the liquid in the second dielectric layer 5 is forced into the thin tube of the first dielectric layer 4. The air originally in the thin tube is replaced by the liquid. According to the formula: ε = ε air V air +ε w V w , where ε air V is the dielectric constant of air. air ε is the air volume fraction. w V is the dielectric constant of the liquid. w For liquid volume fraction, due to ε w >>ε air ε will have a large increment, and according to the capacitance calculation formula: The area S of the overlapping part of the two electrode plates remains unchanged, the dielectric constant ε has a large increment, the distance d between the two electrode plates decreases, so C1 will have a large increment.

[0034] Furthermore, since C2 is only related to the height of the liquid layer, the sensor can be leveled using C2.

[0035] When an external force is applied to the first electrode plate, the first dielectric layer is compressed, the distance between the first and third electrode plates decreases, the third electrode plate moves towards the second electrode plate, and a portion of the liquid in the second dielectric layer enters the holes or tubes in the first dielectric layer through the through-holes, causing the air in the original holes or tubes in the first dielectric layer to be replaced by liquid. According to the formula for calculating the dielectric constant, the dielectric constant has a large increment, and the capacitance value of the first parallel plate capacitor has a large increment.

[0036] In summary, the capacitive sensor structure provided by this invention can significantly improve the measurement sensitivity of capacitive sensors.

[0037] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A differential force-measuring parallel plate capacitive sensor structure, comprising: A cylindrical body (7) is provided with a first electrode plate (1) and a second electrode plate (3) that are parallel to each other, the first electrode plate (1) being located above the second electrode plate (3). The cylindrical body (7) is characterized by further comprising: The third electrode plate (2) is located between the first electrode plate (1) and the second electrode plate (3) and is parallel to the first electrode plate (1) and the second electrode plate (3). The third electrode plate (2) has multiple through holes (6). The first dielectric layer (4) is disposed between the first electrode plate (1) and the third electrode plate (2). The first dielectric layer (4) is made of a flexible and stretchable material and has regular holes or tubes on it. The second dielectric layer (5) is disposed between the second electrode plate (3) and the third electrode plate (2). The second dielectric layer (5) is a liquid with a dielectric constant greater than that of air. The first dielectric layer (4) is made of a material that does not wet the liquid. The first electrode plate (1) moves toward the third electrode plate (2) after being subjected to an external force, and the third electrode plate (2) moves toward the second electrode plate (3) after being subjected to an external force. When an external force is applied to the first electrode plate (1), the first dielectric layer (4) is compressed, and at the same time, the liquid in the second dielectric layer (5) is forced into the holes or tubes of the first dielectric layer (4), and the liquid replaces the air that was originally in the holes or tubes.

2. The differential force-measuring parallel plate capacitive sensor structure as described in claim 1, characterized in that, The first electrode plate (1), the second electrode plate (3) and the third electrode plate (2) are all metal electrode plates.

3. The differential force-measuring parallel plate capacitive sensor structure as described in claim 1, characterized in that, The first electrode plate (1) and the third electrode plate (2) are connected to the electrode lead-out, and the second electrode plate (3) and the third electrode plate (2) are connected to the electrode lead-out.

Images