Pressure sensor
By combining the interdigital electrode layer and the sensitive layer, and using a composite material of TPU, ionic liquid, and hexagonal boron nitride, the problem of balancing conductivity and stretchability in existing interdigital electrode designs is solved, achieving high sensitivity and long-term stable pressure sensor performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2026-04-07
AI Technical Summary
Existing interdigitated electrode designs struggle to balance conductivity and stretchability, limiting sensitivity improvement. The dielectric constant of the sensitive layer exhibits weak response, and the encapsulation process is complex with poor long-term stability. Furthermore, existing sensitive materials suffer from low ion migration efficiency, making it difficult to balance dynamic response speed and mechanical durability.
The sensor employs a combination structure of interdigitated electrode layer and sensitive layer. The interdigitated electrode layer consists of a polyimide substrate layer and a conductive silver paste layer, while the sensitive layer is a composite material of TPU, ionic liquid, and hexagonal boron nitride. These components are connected by screen printing to form an ultra-thin, flexible pressure sensor. The sensor utilizes the reversible ion rearrangement response of the ionic liquid between the hexagonal boron nitride layers to achieve a rapid response in dielectric properties.
The sensitivity and cycle stability of the pressure sensor have been improved, achieving high-sensitivity pressure sensing. The sensor exhibits excellent durability and signal stability under extreme conditions.
Smart Images
Figure CN224095297U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of pressure sensor devices, and relates to a pressure sensor, and more particularly to a highly sensitive pressure sensor with a flexible interdigital structure. Background Technology
[0002] Pressure sensors, as core components for sensing external mechanical signals, have wide applications in industrial automation, medical monitoring, wearable electronics, and robotic tactile sensing. With the rapid development of flexible electronics technology, higher demands are being placed on sensor performance: they not only need high sensitivity to detect minute pressure changes, but also need to be ultra-thin, flexible, and resistant to cyclic fatigue to adapt to complex curved surfaces or dynamic deformation environments.
[0003] Traditional piezoresistive pressure sensors mostly use rigid substrates (such as silicon-based or ceramic-based) and metal electrode structures, which limit their sensitivity and make it difficult to meet the requirements of flexible scenarios. In recent years, sensors based on interdigital electrode structures have become a research hotspot because they can increase the effective overlap area between electrodes and improve the initial capacitance value within a limited planar size. However, existing interdigital electrode designs still face the following challenges: (1) it is difficult to balance the conductivity and stretchability of electrode materials, resulting in insufficient signal stability under large deformation; (2) the dielectric constant of the sensitive layer has a weak response to external forces, limiting the improvement of sensitivity; (3) the packaging process is complex, and the long-term cycling stability is poor. In addition, existing sensitive materials (such as single polymers or carbon-based composite materials) have low ion migration efficiency, and it is difficult to balance dynamic response speed and mechanical durability.
[0004] Therefore, it is essential to provide a new type of pressure sensor. Utility Model Content
[0005] The purpose of this application is to provide a pressure sensor, which includes an interdigitated electrode layer and a sensitive layer stacked together; the interdigitated electrode layer includes a base layer and an electrode layer disposed on the surface of the base layer, and the surface of the interdigitated electrode layer having the electrode layer is connected to the sensitive layer.
[0006] Preferably, the connection method is screen printing connection.
[0007] Preferably, the base layer is a polyimide material layer.
[0008] Preferably, the electrode layer is a conductive silver paste layer with a sheet resistance of 5-10 mΩ / sq.
[0009] Preferably, the thickness of the substrate layer is 100-120 μm, and the thickness of the electrode layer is 10-20 μm.
[0010] Preferably, the electrode layer includes a positive electrode and a negative electrode, which are interconnected by printed wires.
[0011] Preferably, the positive electrode includes at least two first electrode fingers arranged at intervals, and the negative electrode includes at least two second electrode fingers arranged at intervals. At least two of the first electrode fingers and the second electrode fingers are arranged in an alternating pattern. The first electrode fingers and the second electrode fingers are independent of each other and are not connected to each other.
[0012] Preferably, along the direction in which the first electrode finger or the second electrode finger is arranged at intervals, the electrode width of the first electrode finger and / or the second electrode finger is 0.4-0.6 mm.
[0013] Preferably, along the direction in which the first electrode fingers or the second electrode fingers are arranged at intervals, the shortest distance between adjacent first electrode fingers and second electrode fingers is 1-1.5 mm.
[0014] Preferably, the sensitive layer is a TPU layer;
[0015] Preferably, the sensitive layer is a composite material layer of TPU and ILs ionic liquid;
[0016] Preferably, the sensitive layer is a composite material layer of TPU, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide ionic liquid, and hexagonal boron nitride.
[0017] Preferably, with the thickness of the interdigitated electrode layer being 10-20 μm, the thickness of the sensitive layer is 40-60 μm.
[0018] Preferably, the pressure sensor further includes a lower encapsulation layer and an upper encapsulation layer.
[0019] Preferably, the lower encapsulation layer is connected to the interdigitated electrode layer on the side away from the sensitive layer.
[0020] Preferably, the upper encapsulation layer is connected to the sensitive layer on the side away from the interdigitated electrode layer.
[0021] Preferably, both the lower encapsulation layer and the upper encapsulation layer are polyimide substrates.
[0022] Preferably, with the thickness of the sensitive layer being 40-60 μm, the thickness of the lower encapsulation layer is 100-120 μm, and the thickness of the upper encapsulation layer is 100-120 μm.
[0023] Preferably, the lower encapsulation layer and the interdigitated electrode layer are connected by silicone.
[0024] Preferably, the upper encapsulation layer and the sensitive layer are connected by silicone.
[0025] Technical features and beneficial effects of this utility model:
[0026] In this application, an interdigitated electrode layer and a sensitive layer are provided in the pressure sensor. The current flowing through the sensitive layer is transmitted through the interdigitated electrode, and the pressure magnitude is inverted through the current parameter, thereby improving the sensitivity and cycle stability of the pressure sensor.
[0027] In this application, when the sensitive layer is further composed of a specific composite material layer of TPU, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide ionic liquid, and hexagonal boron nitride, during the formation of the sensitive layer, ionic liquid molecules interpenetrate between the hexagonal boron nitride sheets, and achieve rapid response of dielectric properties through reversible ion rearrangement response deformation. This composite material system achieves efficient coupling of dielectric properties and mechanical deformation through multi-scale synergy between components, effectively improving the sensor sensitivity.
[0028] The pressure sensor of this application comprises, from bottom to top, a lower encapsulation layer, an interdigitated electrode layer, a sensitive layer, and an upper encapsulation layer stacked sequentially, making the pressure sensor ultra-thin and flexible, highly sensitive, and with excellent cycle stability. Attached Figure Description
[0029] Figure 1 This is a structure of a pressure sensor in one specific embodiment;
[0030] Wherein, 1 is the interdigitated electrode layer, and 2 is the sensitive layer;
[0031] Figure 2 This is the structure of the interdigitated electrode layer in one specific embodiment;
[0032] Among them, 102 is the base layer and 101 is the electrode layer;
[0033] Figure 3 This is a structure of a pressure sensor in one specific embodiment;
[0034] Wherein, 1 is the interdigitated electrode layer, 2 is the sensitive layer, 3 is the upper encapsulation layer, and 4 is the lower encapsulation layer;
[0035] Figure 4 A schematic diagram of the preparation process of the composite material for the sensitive layer;
[0036] Figure 5 This is a sensitivity curve test diagram of the pressure sensor in a specific implementation method;
[0037] Figure 6 This is a test graph showing the long-term cyclic stability curve of the pressure sensor in a specific implementation. Detailed Implementation
[0038] The technical solution of this utility model will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of this utility model and should not be considered as specific limitations thereof.
[0039] The embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. In the drawings, for clarity, the dimensions of layers, regions, and elements, as well as their relative dimensions, may be exaggerated. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.
[0040] This application provides a pressure sensor, such as... Figure 1 As shown, it includes an interdigitated electrode layer 1 and a sensitive layer 2 stacked together.
[0041] In this application, the sensitive layer covers the interdigitated electrode layer, and the current flowing through the sensitive layer is transmitted through the interdigitated electrode pairs; when the sensitive layer is under pressure, the resistance decreases, thereby increasing the current flowing through the sensitive layer, and the pressure magnitude is inverted based on the current parameters.
[0042] In specific implementation methods, such as Figure 2 As shown, the interdigitated electrode layer includes a substrate layer 102 and an electrode layer 101 disposed on the surface of the substrate layer 102. The electrode layer 101 is disposed on the surface of the substrate layer by screen printing. In the interdigitated electrode layer, the side surface on which the electrode layer is disposed is connected to the sensitive layer. The connection method is screen printing connection.
[0043] In a specific embodiment, the base layer is a polyimide material layer. The polyimide material used in this base layer needs to meet the following requirements: degree of polymerization 100-140, number-average molecular weight 30,000-50,000 g / mol, elongation at break greater than 35%, and density 130-150 kg / m³. 3 Tensile strength greater than 135MPa; electrode layer is a conductive silver paste layer with sheet resistance of 5-10mΩ / sq.
[0044] In this application, the substrate layer is made of PI material, which has good thermal stability; the electrode layer is a conductive silver paste layer with a sheet resistance of 5-10 mΩ / sq, preferably a conductive silver paste layer with a sheet resistance of 7.5 mΩ / sq, which has high conductivity and adhesion. The stretchable conductive silver paste is patterned on the substrate layer by screen printing process.
[0045] In specific embodiments, the thickness of the substrate layer and the electrode layer is not specifically limited, and those skilled in the art can adjust it according to actual needs; preferably, when the thickness of the substrate layer is 100-120μm (e.g., 100μm, 105μm, 110μm, 115μm, 120μm, etc.), the thickness of the screen-printed electrode layer is 10-20μm (e.g., 10μm, 12μm, 15μm, 18μm, 20μm, etc.).
[0046] In a specific embodiment, the electrode layer includes a positive electrode and a negative electrode, which are interconnected by printed wires.
[0047] In a specific embodiment, the positive electrode includes at least two first electrode fingers arranged at intervals, and the negative electrode includes at least two second electrode fingers arranged at intervals. At least two first electrode fingers and the second electrode fingers are arranged in an interleaved manner. The first electrode fingers and the second electrode fingers are independent of each other and are not connected to each other.
[0048] In a specific embodiment, along the direction in which the first electrode fingers or the second electrode fingers are arranged at intervals, the electrode width of the first electrode fingers and / or the second electrode fingers is 0.4-0.6 mm (e.g., 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, etc.);
[0049] In a specific embodiment, along the direction in which the first electrode fingers or the second electrode fingers are arranged at intervals, the shortest distance between adjacent first electrode fingers and second electrode fingers is 1-1.5 mm (e.g., 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc.).
[0050] In a specific implementation, with the thickness of the interdigitated electrode layer being 10-20 μm (e.g., 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, etc.), the thickness of the sensitive layer is 40-60 μm (e.g., 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, etc.).
[0051] In this application, the interdigitated electrode structure can increase the effective overlap area between electrodes within a limited planar dimension, which is beneficial to improving the sensitivity of subsequent signal detection.
[0052] In a specific implementation, the sensitive layer is a TPU material layer. The TPU material selected has a hardness of 86-90A, a density of 1-1.5g / cm3, and an elongation at break of 500-700%. When used in conjunction with the electrode layer, the pressure sensor has good ultra-thin flexibility, high sensitivity, and cycle stability.
[0053] In a specific embodiment, the sensitive layer is a mixed layer of TPU and ILs ionic liquid, and the preparation method is described in CN11966203A.
[0054] In a specific embodiment, the sensitive layer is preferably a composite material layer of TPU, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide ionic liquid, and hexagonal boron nitride.
[0055] In the sensitive layer:
[0056] TPU (thermoplastic polyurethane elastomer rubber) is used as the matrix material. The TPU material selected has a hardness of 86-90A, a density of 1-1.5g / cm3, and an elongation at break of 500-700%. It is a commonly used matrix material for the sensor sensitive layer to meet the basic physical and mechanical properties.
[0057] Ionic liquids, as highly polar additives, can significantly improve the overall dielectric properties of matrix materials due to their high dielectric constants. Free ions in ionic liquids migrate under the influence of an electric field, forming interfacial polarization and enhancing the dielectric response.
[0058] The two-dimensional layered structure of hexagonal boron nitride forms a large number of micro-interfaces in the matrix. Under the action of external force, the change in the interlayer spacing or orientation will dynamically regulate the interfacial polarization effect, further amplifying the change in dielectric constant. Moreover, the uniform dispersion of hexagonal boron nitride forms a three-dimensional network. Under the action of external force, the layers slide or rearrange, changing the charge distribution path and dynamically adjusting the dielectric constant.
[0059] In the sensitive layer, ionic liquid molecules are interspersed between hexagonal boron nitride sheets, and the dielectric properties respond rapidly through reversible ion rearrangement deformation. This composite material system achieves efficient coupling of dielectric properties and mechanical deformation through multi-scale synergy between components, effectively improving the sensor sensitivity.
[0060] In a specific implementation, the method for preparing the sensitive layer is as follows: Figure 4 As shown, the specific preparation method includes:
[0061] S1. Weigh 2g of TPU particles and dissolve them in 5ml of DMF solution. Stir for 2 hours at a stirring rate of 1000r / min and a temperature of 80℃ to obtain a mixed solution.
[0062] S2. Add 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide ionic liquid to the mixed solution obtained in step S1, and continue stirring for 1 hour to obtain a mixed slurry.
[0063] S3. Add 2g of hexagonal boron nitride (h-BN) to the mixed slurry obtained in step S2, heat and stir for 2 hours to obtain the sensitive layer slurry.
[0064] The sensitive layer slurry prepared by the above method has good fluidity and adhesion. It is formed by screen printing on the interdigitated electrode layer.
[0065] In this application, the sensitive layer material uses TPU as a carrier, combined with ionic liquid EMIM and hexagonal boron nitride h-BN. The prepared sensitive layer solution is printed onto the interdigitated electrode structure by screen printing to form a sensitive layer. The prepared sensitive material has a strong ion pumping effect and serves as the dielectric layer of the pressure sensor, which greatly improves the sensor's sensitivity and response characteristics.
[0066] In specific implementation methods, such as Figure 3 As shown, the pressure sensor includes a lower encapsulation layer 4, an interdigitated electrode layer 1, a sensitive layer 2, and an upper encapsulation layer 3 stacked sequentially from bottom to top; wherein, the interdigitated electrode layer 1 and the sensitive layer 2 are arranged in the same manner as described above.
[0067] In a specific implementation, both the lower encapsulation layer and the upper encapsulation layer are polyimide substrate layers.
[0068] In a specific implementation, with the thickness of the sensitive layer being 40-60 μm (e.g., 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, etc.), the thickness of the lower encapsulation layer is 100-120 μm (e.g., 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, etc.), and the thickness of the upper encapsulation layer is 100-120 μm (e.g., 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, etc.).
[0069] In a specific implementation, the lower encapsulation layer is connected to the interdigitated electrode layer via silicone; the upper encapsulation layer is connected to the sensitive layer via silicone.
[0070] In this application, the upper and lower encapsulation layers are made of polyimide substrate. The polyimide material used in the substrate layer needs to meet the following requirements: degree of polymerization of 100-140, number-average molecular weight of 30,000-50,000 g / mol, elongation at break of greater than 35%, and density of 130-150 kg / m³. 3 It has a tensile strength greater than 135 MPa; it also possesses excellent mechanical properties, dielectric properties, and resistance to high temperatures and corrosion.
[0071] In this application, the upper and lower encapsulation layers are bonded to the sensitive layer and interdigitated electrode layer respectively with silicone to the corresponding covering or bonding surfaces, thereby protecting the internal structure of the sensor and increasing the stability of the sensing.
[0072] The sensor described in the above embodiment is fixed on the test platform of a mechanical testing machine. The sensor electrodes are led out using enameled wire. An LCR signal acquisition instrument is used to test the sensor's sensitivity and long-term cyclic stability. Sensitivity, as one of the important indicators for evaluating the performance of a flexible pressure sensor, represents the ratio of the relative change in the sensor's output signal to the change in pressure. It is defined as: S = (ΔI - I0) / ΔP, where ΔI represents the change in current flowing through the sensor, I0 represents the initial current, and ΔP... P This represents the change in pressure.
[0073] When the sensitive layer is a TPU material layer, the maximum sensitivity can reach 214.2 kPa within the 50 kPa range. -1 .
[0074] When the sensitive layer is a composite material of TPU and ILs ionic liquid, the maximum sensitivity can reach 804.27 kPa in the 50 kPa range. -1 .
[0075] When the sensitive layer is a composite material layer of TPU, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide ionic liquid, and hexagonal boron nitride, from Figure 4 It can be seen that as the applied pressure increases, the sensor resistance decreases and the current increases. The maximum sensitivity reaches 804.27 kPa within the 50 kPa range. -1 The extremely high sensitivity demonstrates the advantages of the pressure sensor in this application in pressure sensing.
[0076] In addition, the sensor was subjected to long-term cyclic stability testing by 5000 cycles of pressing under a pressure of 50 kPa using a mechanical testing machine.
[0077] When the sensitive layer is a TPU material layer, the sensor attenuation rate is 27% during the test.
[0078] When the sensitive layer is a composite material of TPU and ILs ionic liquid, the sensor attenuation is 9% during the test.
[0079] When the sensitive layer is a composite material layer of TPU, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide ionic liquid, and hexagonal boron nitride, from Figure 5 It can be seen that the output attenuation of the sensor during the test was only 5%, that is, there was no significant attenuation. The output of the sensor before and after the amplification was also basically consistent, which shows that the pressure sensor of this application has excellent durability under extreme conditions.
[0080] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application without departing from the principles and spirit of this utility model.
Claims
1. A pressure sensor, characterized in that, The pressure sensor includes a stacked interdigitated electrode layer and a sensitive layer; The interdigitated electrode layer includes a base layer and an electrode layer disposed on the surface of the base layer, wherein the surface of the interdigitated electrode layer having the electrode layer is connected to the sensitive layer. The electrode layer includes a positive electrode and a negative electrode; The positive electrode includes at least two first electrode fingers arranged at intervals, and the negative electrode includes at least two second electrode fingers arranged at intervals. Along the direction in which the first electrode finger or the second electrode finger is arranged at intervals, the electrode width of the first electrode finger and / or the second electrode finger is 0.4-0.6 mm; Along the direction in which the first or second electrode fingers are arranged at intervals, the shortest distance between adjacent first and second electrode fingers is 1-1.5 mm.
2. The pressure sensor according to claim 1, characterized in that, The base layer is a polyimide material layer; The electrode layer is a conductive silver paste layer with a sheet resistance of 5-10 mΩ / sq; The thickness of the substrate layer is 100-120 μm, and the thickness of the electrode layer is 10-20 μm.
3. The pressure sensor according to claim 1, characterized in that, The positive and negative electrodes are interconnected by printed wires.
4. The pressure sensor according to claim 3, characterized in that, At least two of the first electrode fingers and the second electrode fingers are arranged in an alternating pattern, and the first electrode fingers and the second electrode fingers are independent of each other and are not connected to each other.
5. The pressure sensor according to claim 1, characterized in that, The sensitive layer is a TPU layer; Alternatively, a composite layer of TPU and ILs ionic liquids.
6. The pressure sensor according to claim 1, characterized in that, With the interdigitated electrode layer having a thickness of 10-20 μm, the thickness of the sensitive layer is 40-60 μm.
7. The pressure sensor according to any one of claims 1-6, characterized in that, The pressure sensor also includes a lower encapsulation layer and an upper encapsulation layer; The lower encapsulation layer is connected to the surface of the interdigitated electrode layer away from the sensitive layer; The upper encapsulation layer is connected to the surface of the sensitive layer on the side away from the interdigitated electrode layer.
8. The pressure sensor according to claim 7, characterized in that, Both the lower encapsulation layer and the upper encapsulation layer are polyimide substrates. With a sensitive layer thickness of 40-60 μm, the lower encapsulation layer has a thickness of 100-120 μm, and the upper encapsulation layer has a thickness of 100-120 μm.
9. The pressure sensor according to claim 7, characterized in that, The lower encapsulation layer and the interdigitated electrode layer are connected by silicone. The upper encapsulation layer and the sensitive layer are connected by silicone.