Piezoresistive sensor with isolation configuration

Abstract

The utility model discloses a piezoresistive sensor with isolation configuration, and belongs to the technical field of flexible piezoresistive sensors. The piezoresistive sensor comprises an electrode layer and a force sensitive structure which are arranged on a substrate, the number of the electrode layers and the number of the substrates are both two. The two electrode layers are respectively arranged on the upper and lower sides of the force-sensitive structure; the electrode layer is provided with a plurality of microstructure electrodes, and the microstructure electrodes are of gradient protruding structures which are distributed in a high-low mode. The length of the force-sensitive structure is larger than that of the electrode layer, and the force-sensitive structure extends out of the two ends of the electrode layer. A filling structure is fixedly connected to one end, away from the force sensitive structure, of the isolation structure. According to the utility model, the isolation structure is introduced, so that the interface stability and durability are improved; by adding the filling structure, the adhesion between the electrode layers is improved, and the toughness and the fracture limit are effectively improved; through the microelectrode structure and the force sensitive structure, the sensitivity and the accuracy are effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of flexible piezoresistive sensors, in particular to a piezoresistive sensor with an isolation configuration. Background Art

[0002] Robots, smart prostheses and medical devices gain sensing capabilities by integrating flexible piezoresistive sensors or electronic skin (e-skin), which plays the role of mechanical receptors in biological skin. Many types of pressure sensors have been proposed. According to their working mechanism, there are several main types, including piezoresistive, piezoelectric, piezocalytic and triboelectric. For self-powered piezoelectric and triboelectric, although they can achieve self-power, they have poor restoration of key information such as pressure size and have large interference. Flexible piezoresistive sensors can easily collect many deformation signals such as compression, bending and twisting due to their simple working principle, and convert them into electrical signals. Therefore, they have been greatly developed and are expected to become the electronic skin of the future.

[0003] A major challenge of high-performance flexible piezoresistive sensors is the inherent conflict between sensitivity and mechanical stability. Most piezoresistive sensors use stacked functional layer structures, such as two electrode layers surrounding a sensitive material layer. Due to the significant difference in modulus and strain, the interface between the electrode layer and the active material is mechanically delaminated under conditions such as bending due to poor adhesion. This problem becomes particularly evident under extreme conditions such as stretching or twisting, which may cause temporary failure of the sensor. Although the mechanical delamination or fracture of a single device can be mitigated by adding a packaging layer directly to the outside of the sensor, in the case of high-resolution electronic skin composed of multiple sensing units, the traditional method of adding packaging materials to the outer surface often leads to misalignment and leakage of the sensing units. Existing high-performance flexible piezoresistive sensors use stacked functional layer structures, and the electrode layer and the active material surface are directly connected. On the one hand, the electrode layer lacks sufficient flexible structure, and on the other hand, the adhesion between the electrode layer and the material is poor, which is not conducive to the simultaneous improvement of the sensitivity and mechanical stability of the piezoresistive sensor. Therefore, how to solve the inherent conflict between the sensitivity and mechanical stability of high-performance flexible piezoresistive sensors and ensure the high sensitivity and high mechanical stability of high-performance flexible piezoresistive sensors is one of the key issues that need to be solved urgently. Utility Model Content

[0004] The utility model aims to provide a piezoresistive sensor with an isolation configuration to solve the problem that there is an inherent conflict between the sensitivity and mechanical stability of existing high-performance flexible piezoresistive sensors, and it is difficult to have both high sensitivity and high mechanical stability.

[0005] The technical solution of the utility model to solve the above technical problems is as follows:

[0006] An interface bonding type piezoresistive sensor with an isolation configuration includes: an electrode layer and a force sensitive structure disposed on a substrate;

[0007] Two electrode layers and two substrates are provided;

[0008] Two electrode layers are respectively arranged on the upper and lower sides of the force-sensitive structure;

[0009] A plurality of microstructure electrodes are arranged on the electrode layer, and the microstructure electrodes are gradient convex structures with high and low distribution;

[0010] The force-sensitive structure is longer than the electrode layer and extends out from both ends of the electrode layer. The isolation structure is clamped and connected to both ends of the force-sensitive structure.

[0011] A filling structure is fixedly connected to one end of the isolation structure away from the force-sensitive structure.

[0012] The beneficial effects of the utility model are as follows: the utility model forms the main body of the piezoresistive sensor through a flexible electrode structure and a force-sensitive structure protected by an isolation structure, and is combined with an electrode layer having a microstructure electrode with a high and low distributed trapezoidal protrusion structure, thereby effectively improving the sensitivity and accuracy of the piezoresistive sensor. The mechanical properties of the piezoresistive sensor are effectively improved by the isolation structure set at both ends of the force-sensitive structure and the filling structure set around it. According to the peeling experiment in the test example, compared with Comparative Examples 1 and Comparative Examples 2 in which no isolation structure is set or no isolation structure and filling structure are set, the interface toughness and fracture limit are significantly improved.

[0013] Furthermore, the materials of the microstructure electrode and the substrate are any one of polydimethylsiloxane, polyurethane or copolyester; and a gold-plated layer is provided on the surface of the microstructure electrode.

[0014] Furthermore, the microstructure electrode is prepared by the following method: a base material is etched to obtain a mold with etching pits, polydimethylsiloxane, polyurethane or copolyester is scraped on the mold, and then cured to obtain the microstructure electrode; the surface gold plating method of the base material is magnetron sputtering.

[0015] The beneficial effect of adopting the above further technical solution is: the utility model can effectively control the sensing performance and improve the sensitivity and accuracy of the sensing performance of the piezoresistive sensor by using polydimethylsiloxane, polyurethane or copolyester with a gradient protrusion structure as a flexible electrode.

[0016] Furthermore, the force-sensitive structure is a circular structure with a diameter of 5-10 mm.

[0017] Preferably, the force-sensitive structure is a circular structure with a diameter of 8 mm.

[0018] Furthermore, the force-sensitive structural material is paper fiber containing polymerized polyaniline and polystyrene.

[0019] Furthermore, the isolation structure is an annular structure with an inner diameter of 4-9 mm and an outer diameter of 10-15 mm.

[0020] Preferably, the isolation structure is an annular structure with an inner diameter of 7 mm and an outer diameter of 12 mm.

[0021] Furthermore, the isolation structure is an acrylic tape or a polyurethane tape.

[0022] The beneficial effect of adopting the above-mentioned further technical scheme is as follows: the utility model uses acrylic tape or polyurethane tape as the isolation structure, which is tightly bonded to the force-sensitive structure, which not only prevents the force-sensitive structure from being dislocated and leaked, but also effectively avoids the entry of cross-linking solution during the processing process, thereby affecting the sensing performance.

[0023] Furthermore, the material of the filling structure is any one of polydimethylsiloxane, polyurethane or copolyester.

[0024] The invention discloses an interface bonding type piezoresistive sensing array with an isolation structure configuration, which is composed of a plurality of interface bonding type piezoresistive sensors with an isolation structure configuration.

[0025] The utility model has the following beneficial effects:

[0026] The utility model introduces an isolation structure to effectively improve the interface stability of the piezoresistive sensor, and there is no problem of separation even under bending and twisting, which improves the durability of the sensor; by adding a filling structure, the adhesion between the electrode layer and the filling structure is effectively improved, and the toughness and fracture limit of the piezoresistive sensor are effectively improved; through a microelectrode structure with a surface gradient protrusion structure and a force-sensitive structure composed of paper fibers of in-situ polymerization of polyaniline and polystyrene, the sensitivity and accuracy of the sensing performance of the piezoresistive sensor are effectively improved. The utility model can be prepared by stacking layers from bottom to top, and has the advantages of ultra-thin and ultra-light, high precision, strong applicability and easy large-scale manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the interface bonding type piezoresistive sensor with isolation configuration in Example 1, wherein 1-electrode layer, 2-force sensitive structure, 3-isolation structure, 4-filling structure, 5-substrate, 11-microstructure electrode;

[0028] Figure 2 Schematic diagram of the microelectrode structure;

[0029] Figure 3Schematic diagram of the structure of the interface bonding type piezoresistive sensor with isolation configuration in Example 2, wherein 1-electrode layer, 2-force sensitive structure, 3-isolation structure, 4-filling structure, 5-substrate, 11-microstructure electrode;

[0030] Figure 4 Schematic diagram of the structure of the interface bonding type piezoresistive sensor with isolation configuration in Example 3, wherein 1-electrode layer, 2-force sensitive structure, 3-isolation structure, 4-filling structure, 5-substrate, 11-microstructure electrode;

[0031] Figure 5 The electrical performance test result diagram in Experimental Example 1, wherein the single layer is Example 1, the double layer is Example 2, and the triple layer is Example 3;

[0032] Figure 6 This is a graph of the interface stability test results in Experimental Example 2, wherein isolation + cross-linking is Example 1, no isolation + cross-linking is Comparative Example 1, and no isolation + no cross-linking is Comparative Example 2. DETAILED DESCRIPTION

[0033] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0034] Embodiment 1:

[0035] An interface bonding type piezoresistive sensor with an isolation configuration comprises: an electrode layer 1 and a force sensitive structure 2 arranged on a substrate;

[0036] Two electrode layers 1 and two substrates 5 are provided;

[0037] Two electrode layers 1 are respectively arranged on the upper and lower sides of the force-sensitive structure 2;

[0038] A plurality of microstructure electrodes 11 are arranged on the electrode layer 1 . The microstructure electrodes 11 are gradient protrusion structures with high and low distribution.

[0039] The force-sensitive structure 2 is longer than the electrode layer 1 and extends out of two ends of the electrode layer 1 . The isolation structure 3 is clamped and connected to the two ends of the force-sensitive structure 2 .

[0040] A filling structure 4 is fixedly connected to one end of the isolation structure 3 away from the force-sensitive structure 2 .

[0041] The microstructure electrode 11 and the substrate 5 are both made of polydimethylsiloxane; a gold-plated layer is provided on the surface of the microstructure electrode 11 .

[0042] The microstructure electrode 11 is prepared by the following method: etching the polyimide plate of the base material by an ultraviolet laser marking machine, etching a pit structure on the base material so that the spacing between each pit is 100 μm, marking twice, and obtaining a gradient structure micropit; then mixing 10 g of polydimethylsiloxane with 1 g of curing agent, magnetically stirring for 30 minutes, vacuum degassing for 30 minutes, and then scraping the polydimethylsiloxane and curing agent mixture on the polyimide plate, heating at 80°C for 45 minutes, and removing it after curing to obtain the following Figure 2 The microstructure electrode 11 is shown.

[0043] The force-sensitive structure 2 is a circular structure with a diameter of 8 mm, and is made of paper fibers containing polymerized polyaniline and polystyrene.

[0044] Paper fibers containing polymerized polyaniline and polystyrene were prepared by the following method: 91.6 μL of aniline and 416 μL of carboxylated styrene microspheres were mixed in 50 mL of 1 mol / L hydrochloric acid solution, and ultrasonicated for 30 min to obtain solution a; 228.4 mg of ammonium persulfate (APS) was dissolved in 50 mL of 1 mol / L hydrochloric acid solution, and stirred for 30 min to obtain solution b; solution a was poured into solution b, and a 5 cm×5 cm piece of paper fiber was added during the pouring process, and the mixture was reacted in an ice bath at 0°C for 8 h, and dried at room temperature to obtain the obtained solution.

[0045] The isolation structure 3 is a ring structure with an inner diameter of 7 mm and an outer diameter of 12 mm, and is made of acrylic tape.

[0046] The filling structure 4 is made of polydimethylsiloxane.

[0047] Embodiment 2:

[0048] An interface bonding type piezoresistive sensor with an isolation configuration, the structure of which is the same as that of embodiment 1, except that it includes two force-sensitive structures 2 and two isolation structures 3, such as Figure 3 shown.

[0049] Embodiment 3:

[0050] An interface bonding type piezoresistive sensor with an isolation configuration, the structure of which is the same as that of Embodiment 2, except that it includes three force-sensitive structures 2 and three isolation structures 3, such as Figure 4 shown.

[0051] Comparative Example 1:

[0052] An interface bonding type piezoresistive sensor has the same structure as that of the first embodiment, except that the isolation structure 3 is not included.

[0053] Comparative Example 2:

[0054] An interface adhesive piezoresistive sensor has the same structure as that of embodiment 1, except that the isolation structure 3 and the filling structure 4 are not included.

[0055] Test Example 1: Electrical Performance Test

[0056] The electrical performance was tested using a dynamometer and a linear motor. The interface bonding piezoresistive sensor obtained in Example 1-3 was installed on a fixed surface. The linear motor was allowed to hit the piezoresistive sensor back and forth. The force was recorded by the dynamometer installed at the front end of the linear motor. In addition, the conductive carbon cloth led out of the piezoresistive sensor was connected to SR-570, a constant voltage of 0.1V was applied to the device, and SR-570 was used to collect current signals. LabVIEW and a data acquisition system were used to record the output of the current signals. The experimental results are shown in the figure. Figure 5 shown.

[0057] According to the experimental results, when the number of layers of the force-sensitive structure 2 and the isolation structure 3 increases, the response range of the device is widened, but the sensitivity is reduced. Among them, the double-layer structure (ie, embodiment 2) has the highest sensitivity and a higher response range, and is the best embodiment of the utility model.

[0058] Test Example 2: Interface stability test

[0059] The piezoresistive sensors prepared in Example 1 and Comparative Examples 1-2 were subjected to a 180-degree peeling test using a mechanical testing machine to measure their toughness and fracture limit. The experimental results are shown in FIG. Figure 6 shown.

[0060] According to the experimental results, the comparative example 2 without the filling structure 4 has relatively weak mechanical properties (interface toughness is less than 2 J / m) due to the weak adhesion between the isolation structure 3 and the electrode layer 1. 2 , the fracture limit is less than 4N / m); the comparative example 1 without the isolation structure 3 has a relatively high interface toughness (86.05J / m 2 ) and fracture limit (48.40N / m), but there is still a large gap between the piezoresistive sensor obtained in Example 1 of the utility model. The interface toughness of the piezoresistive sensor obtained in Example 1 reaches 93.39J / m 2 , the fracture limit reached 66.34N / m. The main reason is that the arrangement of the isolation structure 3 hinders the expansion of the crack, and the crack is fixed at the edge of the isolation structure 3 until the peeling force exceeds the maximum peeling force. Therefore, when the crack is pinned along the edge of the isolation structure 3, the peeling force gradually increases, and after passing through the isolation structure 3, the peeling force gradually decreases.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A piezoresistive sensor with an isolation configuration, characterized in that: include: An electrode layer (1) and a force-sensitive structure (2) arranged on a substrate (5); Two of each of the electrode layer (1) and the substrate (5) are provided; The two electrode layers (1) are respectively arranged on the upper and lower sides of the force-sensitive structure (2); A plurality of microstructure electrodes (11) are arranged on the electrode layer (1), and the microstructure electrodes (11) are gradient protrusion structures with high and low distribution; The force-sensitive structure (2) is longer than the electrode layer (1) and extends beyond the two ends of the electrode layer (1); the isolation structure (3) is clamped and connected to the two ends of the force-sensitive structure (2); A filling structure (4) is fixedly connected to one end of the isolation structure (3) away from the force-sensitive structure (2).

2. The piezoresistive sensor with an isolation configuration according to claim 1, characterized in that: The materials of the microstructure electrode (11) and the substrate (5) are any one of polydimethylsiloxane, polyurethane or copolyester; and a gold-plated layer is provided on the surface of the microstructure electrode (11).

3. The piezoresistive sensor with an isolation configuration according to claim 1, characterized in that: The force-sensitive structure (2) is a circular structure with a diameter of 5-10 mm.

4. The piezoresistive sensor with an isolation configuration according to claim 1 or 3, characterized in that: The material of the force-sensitive structure (2) is paper fiber containing polymerized polyaniline and polystyrene.

5. The piezoresistive sensor with an isolation configuration according to claim 1, characterized in that: The isolation structure (3) is an annular structure with an inner diameter of 4-9 mm and an outer diameter of 10-15 mm.

6. The piezoresistive sensor with an isolation configuration according to claim 1 or 5, characterized in that: The isolation structure (3) is an acrylic tape or a polyurethane tape.

7. The piezoresistive sensor with an isolation configuration according to claim 1, characterized in that: It comprises a plurality of the force-sensitive structures (2) and a plurality of the isolation structures (3).

8. The piezoresistive sensor with an isolation configuration according to claim 1, characterized in that: The material of the filling structure (4) is any one of polydimethylsiloxane, polyurethane or copolyester.

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