Passive capacitive sensor based on light-induced deformation material regulation and control and preparation method thereof

Abstract

The invention provides a passive capacitive sensor based on light-induced deformation material regulation and control and a preparation method thereof, and the passive capacitive sensor comprises an upper polar plate, a lower polar plate, a dielectric layer located between the two polar plates, and at least one light-induced deformation strip disposed between the upper polar plate and the lower polar plate. Two ends of the photo-induced deformation strip are respectively fixed on the upper polar plate and the lower polar plate, and the photo-induced deformation strip is made of a photo-induced bending deformation material; hollow electrodes are arranged on the surfaces of the upper polar plate and the lower polar plate; when external illumination acts on the light-induced deformation strip, the strip bends and deforms and drives the distance between the upper pole plate and the lower pole plate to change, and passive continuous adjustment of the capacitance value is achieved. Strips are driven to deform through illumination intensity changes so as to adjust the distance between the polar plates in a non-contact mode, and continuous dynamic regulation and control of the capacitance value are achieved.

Description

Technical Field

[0001] This invention relates to the field of passive capacitive sensor technology, specifically to a passive capacitive sensor and method based on photodeformable material modulation. Background Technology

[0002] As a fundamental electronic component, the capacitance C of a capacitor is typically determined by the plate area A, the plate spacing d, and the dielectric constant ε, following the formula C = εA / d. Traditional variable capacitors mainly achieve capacitance changes by mechanically adjusting the plate spacing or effective area. In recent years, with the development of smart materials, researchers have attempted to achieve non-contact control of capacitors using materials such as electrostriction and magnetostriction. However, these methods often require complex external field control and consume a lot of energy.

[0003] Photodeformable materials are a class of smart materials capable of directly converting light energy into mechanical deformation, exhibiting reversible and rapid response characteristics in the ultraviolet to near-infrared bands. Current technological bottlenecks mainly lie in: traditional mechanically adjustable capacitors being large and slow in response; variable capacitors based on smart materials often rely on electric or magnetic field control, resulting in complex systems; and simple light-controlled switching devices lack continuously adjustable capacitive output characteristics. Therefore, developing a light-controlled variable capacitor that is simple in structure, fast in response, precisely controlled, and requires no physical contact has significant scientific and practical value. Summary of the Invention

[0004] The purpose of this invention is to provide a passive capacitive sensor based on photodeformable material modulation and its fabrication method, so as to overcome the shortcomings of the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A passive capacitive sensor based on photodeformable material control includes an upper electrode, a lower electrode, and a dielectric layer between the two electrodes. It also includes at least one photodeformable strip disposed between the upper and lower electrodes, with both ends of the strip fixed to the upper and lower electrodes respectively. The strip is made of a photodeformable material. The surfaces of the upper and lower electrodes are provided with perforated electrodes. When external light shines on the photodeformable strip, the strip undergoes bending deformation, driving a change in the distance between the upper and lower electrodes, thereby achieving passive continuous adjustment of the capacitance value.

[0007] Furthermore, the photodeformable strips are made of liquid crystal elastomer or azobenzene-polysiloxane composite material, with a thickness of 10-100 μm, and the number of strips is 4-12, arranged radially or in an array.

[0008] Furthermore, the hollowed-out electrode is a mesh or ring-shaped transparent conductive structure, including a silver nanowire mesh, an indium tin oxide pattern, or a gold film etched circuit, with a line width of 1-10 μm and a spacing of 50-500 μm.

[0009] Furthermore, the upper and lower electrode plates are made of photocurable resin with a light transmittance of greater than 85% using 3D printing technology, with a thickness of 100-200μm, and the electrode plate surface is provided with positioning marks for achieving precise assembly of the strips.

[0010] Furthermore, the curvature of the photodeformation strip is controlled by adjusting the incident light intensity, thereby continuously changing the electrode spacing. When the illumination is enhanced, the electrode spacing increases, leading to a decrease in capacitance; when the illumination is weakened, the time interval decreases, leading to an increase in capacitance. The capacitance change ΔC and the light intensity I satisfy a polynomial relationship: ΔC = k1I + k2I 2 +…+k n I n goodness of fit R 2 >0.99.

[0011] Furthermore, it also includes a reset mechanism, which is the elastic layer of the electrode itself or an additional elastic component, used to drive the electrode spacing to return to its initial value when the light intensity decreases.

[0012] A method for fabricating a passive capacitive sensor based on photodeformable materials, used to fabricate the aforementioned passive capacitive sensor, includes the following steps:

[0013] S1. A transparent electrode plate with a light transmittance of more than 85% is prepared using photopolymerization 3D printing technology;

[0014] S2. A hollow electrode is formed on the surface of the electrode plate by mask sputtering or photolithography.

[0015] S3. Apply the photodeformation material solution to the template, cure it under ultraviolet light to form a strip, and then cut it into the preset size;

[0016] S4. Use UV-curing adhesive to bond the two ends of the photodeformation strip to the upper and lower electrodes respectively;

[0017] S5. The sensor is packaged using a PDMS sealed frame with a frame width of 1-3mm.

[0018] As can be seen from the above technical solutions, compared with the prior art, the present invention has the following technical advantages:

[0019] 1. The passive capacitive sensor of this invention adopts a non-contact light control mechanism. The adjustment process does not rely on any physical contact or complex wiring. The capacitance adjustment is achieved entirely through changes in light intensity. This avoids the design of complex moving parts, greatly reduces mechanical wear and failure risk, thereby extending the service life of the device. Moreover, it does not require active signal transmission (such as infrared or ultrasonic waves) and only relies on changes in ambient light, resulting in extremely low power consumption.

[0020] 2. This invention uses a photodeformable material with a response time in the sub-second range, which makes the capacitance adjustment speed far exceed that of traditional mechanical variable capacitors;

[0021] 3. By optimizing the pattern design of the strips and the layout of the illuminated areas, this invention can not only achieve overall capacitance adjustment, but also achieve gradient changes in local capacitance, thus meeting the needs of different applications.

[0022] 4. By optimizing the design of the strip height and initial spacing, this invention can achieve a larger capacitance change ratio, giving it a significant advantage in applications requiring a wide range of capacitance adjustment. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of the overall structure of the passive capacitive sensor of the present invention;

[0024] Figure 2 This is a diagram illustrating the deformation process of the photodeformable strip of the present invention.

[0025] Figure 3 This is a schematic diagram of the hollow electrode structure of the present invention;

[0026] In the figure: 1. Upper electrode; 2. Lower electrode; 3. Photodeformation stripe; 4. Hollow electrode. Detailed Implementation

[0027] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] like Figure 1-2 The passive capacitive sensor based on photodeformable material control shown includes an upper electrode 1, a lower electrode 2, and a dielectric layer located between the two electrodes. It also includes a photodeformable strip 3 disposed between the upper electrode 1 and the lower electrode 2. The two ends of the photodeformable strip 3 are fixed to the upper electrode 1 and the lower electrode 2, respectively. When external light is applied to the photodeformable strip 3, the strip undergoes bending deformation and drives the spacing between the upper electrode 1 and the lower electrode 2 to change, thereby realizing passive continuous adjustment of the capacitance value.

[0029] This invention's passive capacitive sensor employs a non-contact light control mechanism. The adjustment process does not rely on any physical contact or complex wiring; capacitance adjustment is achieved entirely through changes in light intensity. This makes it particularly suitable for applications in enclosed environments, miniaturized devices, or within biological organisms. It avoids complex moving part designs, greatly reducing mechanical wear and the risk of failure, thereby extending the device's lifespan. Furthermore, it does not require active signal emission (such as infrared or ultrasonic waves), relying solely on changes in ambient light, resulting in extremely low power consumption. Simultaneously, it utilizes photodeformable materials with sub-second response times, enabling capacitance adjustment speeds far exceeding those of traditional mechanical variable capacitors.

[0030] Specifically, the upper electrode 1 and lower electrode 2 are made of modified Somos PerFORM resin with a light transmittance of 88% using 3D printing technology, with a thickness of 150μm. The electrode surface is provided with positioning marks for precise strip assembly. The photodeformable strip 3 is made of azobenzene-polysiloxane composite material (this material has strong photoresponse performance and can undergo significant deformation under ultraviolet light irradiation; it can also be made of photo-bending deformation materials such as liquid crystal elastomers), with a thickness of 50μm, a width of 2mm, and 8 strips arranged radially. The two ends of the photodeformable strip 3 are fixed to the lower electrode 1 and lower electrode 2 respectively by using ultraviolet curing adhesive (NOA81), thereby ensuring the stability and reliability of the sensor in actual use.

[0031] like Figure 3 As shown, the surfaces of the upper electrode plate 1 and the lower electrode plate 2 in this preferred embodiment are provided with hollow electrodes 4, which are mesh-like transparent conductive structures. Specifically, a gold film (with a linewidth of 5 μm and a spacing of 200 μm) is deposited on the surface of the transparent electrode plate by mask sputtering deposition technology, and then an array of circular insulating tape is applied. This method can achieve the hollow design of the electrode, and finally form an electrode with uniform conductive properties on the surface of the electrode plate, thereby improving the photoelectric signal capture capability.

[0032] The passive capacitive sensor described in this preferred embodiment also includes a reset mechanism, which is an elastic layer of the electrode plate itself or an additional elastic component, used to drive the electrode plate spacing to return to the initial value when the light intensity decreases; at the same time, in order to effectively prevent the ambient humidity from affecting the measurement accuracy of the sensor, a PDMS sealed frame is used to encapsulate the sensor, with a frame width of 2mm, to ensure that it can still maintain high-precision measurement under different environmental conditions, and the overall size is 20mm×20mm×0.8mm.

[0033] Since the curvature of the photodeformation strip 3 is controlled by adjusting the incident light intensity, the electrode spacing is continuously changed; when the illumination is enhanced, the electrode spacing increases, resulting in a decrease in capacitance; when the illumination is weakened, the time interval decreases, resulting in an increase in capacitance. In this preferred embodiment, the prepared sensor is calibrated through a dark box experiment. The experiment uses a 405nm laser (adjustable laser power, power range of 0-200mW, laser spot diameter of 15mm) to vertically irradiate the center of the sensor. Under laser irradiation, the capacitance value of the sensor changes with the light intensity. To monitor the capacitance change in real time, an LCR meter (test frequency of 1MHz) is used to measure the capacitance value. By recording the relationship between the laser light intensity and the capacitance value, a quantitative relationship model between light intensity and capacitance is established. A polynomial fitting method is used, combined with the measured data, to construct a mathematical model between light intensity and capacitance value, ensuring the accuracy and stability of the model. Specifically, the capacitance change ΔC and the light intensity I satisfy a polynomial relationship: ΔC=k1I+k2I 2 +…+k n I n goodness of fit R 2 >0.99.

[0034] In practical applications, by optimizing the strip pattern design and the layout of the illuminated area, not only can the overall capacitance be adjusted, but also the gradient change of local capacitance can be achieved, thus meeting the needs of different applications, such as optical touch and pressure sensing. At the same time, by optimizing the strip height and initial spacing design, this invention can obtain a large capacitance change ratio (e.g., 10:1 or more), giving it a significant advantage in applications that require large-scale capacitance adjustment.

[0035] Meanwhile, to meet higher resolution and accuracy requirements, the passive capacitive sensor described in this preferred embodiment can be extended to an array sensor structure: by arranging multiple variable capacitor units in an M×N matrix, each unit can independently respond to changes in local illumination, forming a high-resolution optical touch or pressure distribution sensing system. This array sensor can be widely used in photoelectric sensing, touchscreen technology, pressure sensing, smart wearable devices, and other fields. The array sensor structure is further illustrated below through two specific application examples:

[0036] Application Example 1: Building Lighting Control Louver System

[0037] In this embodiment, a 20×20 sensor array (total size 1000mm×1000mm) is applied to a building's interior lighting control system. Specifically, the 20×20 sensor array is attached to areas with moderate indoor lighting to comprehensively and in real-time monitor the light distribution in various indoor areas. Each sensor can sense the ambient light intensity and adjust the angle of the blinds according to changes in light intensity to optimize indoor lighting.

[0038] When the intensity of external ambient light changes, the sensor array detects local light intensity differences based on changes in capacitance values ​​in different areas. When the capacitance value of a certain area is lower than a preset threshold, it indicates that the light intensity in that area is too high (strong light). The sensor will trigger the central processing unit control system to drive the louver servo motor corresponding to that area (step angle of 1.8). The louver servo motor will rotate 15° to block the excessive light, thereby adjusting the indoor lighting environment.

[0039] When the capacitance value in the area returns to the normal range, the central processing unit stops adjusting, and the louver slats return to their original positions. The entire process achieves real-time, automatic indoor lighting adjustment, improving comfort while saving energy. Through intelligent control algorithms, the louver system can not only effectively control indoor lighting but also flexibly adjust according to actual needs, enhancing both indoor comfort and energy efficiency.

[0040] Application Example 2: Smart Home Contactless Gesture Control System

[0041] In this embodiment, the core is a light-controlled variable capacitor array (4×4); when the user's palm moves within 10cm above the sensor, the ambient light (or 450nm auxiliary LED light source) is blocked to varying degrees, causing the bending state of the LCE strip to change in real time: when the palm is fully covered, the capacitance value increases from 1pF to 5pF, and when the finger slides, the adjacent units produce a gradient change of 0.5-3pF.

[0042] In a smart lighting scenario, the system is embedded in the ceiling light housing to achieve the following interactions: 1) Hover your hand for 2 seconds to wake up the system (all unit capacitors rise to 3pF simultaneously); 2) Wave your hand up and down to adjust the brightness (when the capacitance change rate is >1pF / s, linear brightness adjustment is triggered); 3) Draw a clockwise circle to switch the color temperature (the array units generate capacitance peaks at 0.2s intervals in a circular sequence).

[0043] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A passive capacitive sensor based on light-induced deformation material regulation, comprising an upper electrode plate (1), a lower electrode plate (2) and a dielectric layer between the two electrode plates, characterized in that, Also include: At least one light-induced deformation strip (3) is arranged between the upper plate (1) and the lower plate (2), both ends of the light-induced deformation strip (3) are fixed on the upper plate (1) and the lower plate (2) respectively, and the material is light-induced bending deformation material; The surface of the upper plate (1) and the lower plate (2) is provided with a hollow electrode (4); When external light acts on the light-induced deformation strip (3), the strip produces bending deformation and drives the distance between the upper plate (1) and the lower plate (2) to change, realizing passive continuous adjustment of the capacitance value.

2. The passive capacitive sensor based on light-induced deformable material regulation according to claim 1, characterized in that, The light-induced deformation strip (3) is made of liquid crystal elastomer (LCE) or azobenzene-polysiloxane composite material, the thickness is 10-100μm, the number of strips is 4-12 and is arranged in radial or array.

3. The passive capacitive sensor based on light-induced deformable material regulation according to claim 1, wherein, The hollow electrode (4) is a net-like or ring-shaped transparent conductive structure, including silver nanowire grid, indium tin oxide (ITO) pattern or gold film etching circuit, the line width is 1-10μm and the pitch is 50-500μm.

4. The passive capacitive sensor based on light-induced deformable material regulation according to claim 1, wherein, The upper plate (1) and the lower plate (2) are made of light-cured resin with light transmittance greater than 85% by 3D printing technology, the thickness is 100-200μm, and the surface of the plate is provided with positioning marks for realizing accurate assembly of the strip.

5. The passive capacitive sensor based on light-induced deformable material regulation according to claim 1, wherein, The curvature of the photodeformation strip (3) is controlled by adjusting the incident light intensity, thereby continuously changing the electrode spacing. When the light intensity increases, the electrode spacing increases, resulting in a decrease in capacitance; when the light intensity decreases, the time interval decreases, resulting in an increase in capacitance. The capacitance change ΔC and the light intensity I satisfy a polynomial relationship: ΔC=k1I+k2I 2 +…+k n I n goodness of fit R 2 >0.

99.

6. The passive capacitive sensor based on light-induced deformable material regulation according to claim 1, wherein, It also includes a reset mechanism, which is an elastic layer of the plate itself or an additional elastic member, used to drive the plate distance to restore the initial value when the light decreases.

7. A method for the preparation of a passive capacitive sensor based on light-induced deformation material, for the production of a passive capacitive sensor according to any one of claims 1 to 6, characterized in that The steps include: S1, using light-cured 3D printing technology to prepare transparent plate with light transmittance greater than 85%; S2, forming a hollow electrode on the surface of the plate by mask sputtering or photolithography process; S3, coating the light-induced deformation material solution on the template, cutting into the preset size after ultraviolet curing and forming into strip shape; S4, using ultraviolet curing adhesive to bond the two ends of the light-induced deformation strip to the upper and lower plates respectively; S5, using PDMS sealing frame to package the sensor, the frame width is 1-3mm.

Images