Triboelectric pressure sensor with gradient layered structure

Abstract

The invention discloses a triboelectric pressure sensor with a gradient layered structure. The triboelectric pressure sensor comprises a conductive shielding layer I (1), an insulating layer I (2), an electrode layer I (3), a friction layer, an electrode layer II (5), an insulating layer II (6) and a conductive shielding layer II (7) which are stacked in sequence, the gradient layered structure design is provided, the linear range is expanded through layered and staged response pressure, the shielding layer is integrated to suppress interference, materials and the process are optimized, and stability and manufacturability are improved.

Description

Technical Field

[0001] The present invention relates to the field of pressure sensors, and specifically to a triboelectric pressure sensor with a gradient hierarchical structure. Background Art

[0002] As a key device for real-time perception of mechanical signals, pressure sensors play an irreplaceable role in the fields of wearable health monitoring, intelligent human-machine interaction, industrial automation, etc. Their performance directly affects the accuracy and reliability of the system. In recent years, pressure sensors based on triboelectric nanogenerators (TENGs) have received extensive attention due to their self-powered characteristics, high sensitivity, and flexible compatibility, and have gradually become a research hotspot for replacing traditional sensors. However, existing TENG pressure sensors still have significant defects in practical applications. For example, traditional designs mostly use homogeneous materials or single microstructures (such as micro-protrusions or micro-column arrays with a fixed height). Although they have high sensitivity in the low-pressure range (0.1 - 1 kPa), under high-pressure conditions (such as exceeding 3 kPa), signal nonlinear distortion occurs due to material compression saturation, the dynamic range is limited, and it is difficult to achieve high-linear response over a wide pressure range. At the same time, human static electricity and environmental electromagnetic noise are easily coupled to the signal link through the electrodes, resulting in baseline drift or false signals. Existing solutions rely on post-algorithm filtering and cannot shield interference from the physical structure. Especially in wearable scenarios, the problem of signal distortion is prominent when the sensor is in direct contact with the human body. In terms of long-term stability, common flexible materials (such as PDMS or foam) are prone to charge loss in high-temperature and high-humidity environments and are prone to plastic deformation after repeated compression, resulting in significant attenuation of sensitivity. In addition, high-sensitivity designs rely on complex microfabrication processes (such as femtosecond laser engraving or nanoimprinting), which are costly and difficult to mass-produce, limiting their popularity in the consumer electronics field. Although TENG technology has the advantage of self-driving, some sensors still require external circuits to support signal conditioning or storage, with low system integration and single function, and it is difficult to adapt to multi-modal sensing requirements. These problems jointly restrict the transformation of TENG pressure sensors from the laboratory to practical applications, and there is an urgent need to achieve breakthroughs through structural design and material optimization. Summary of the Invention

[0003] The object of the present invention is to provide a triboelectric pressure sensor with a gradient hierarchical structure, including a conductive shielding layer I, an insulating layer I, an electrode layer I, a friction layer, an electrode layer II, an insulating layer II, and a conductive shielding layer II stacked in sequence.

[0004] The friction layer includes a non-gradient friction layer and a gradient friction layer.

[0005] Two surfaces of the non-gradient friction layer are respectively in contact with the gradient friction layer and the electrode layer I.

[0006] The gradient friction layer is a gradient hierarchical structure.

[0007] Two surfaces of the gradient friction layer are respectively in contact with the electrode layer II and the non-gradient friction layer.

[0008] Furthermore, the triboelectric pressure sensor realizes pressure grading detection through the contact and separation between the non-gradient friction layer and the gradient friction layer.

[0009] Furthermore, when an external pressure is applied, the surfaces of the gradient friction layer in contact with the non-gradient friction layer carry positive and negative charges respectively due to the triboelectrification effect. During the contact process between the gradient friction layer and the non-gradient friction layer, due to the principle of electrostatic induction, driving charges transfer between the electrode layer I and the electrode layer II through an external circuit.

[0010] Furthermore, both the conductive shielding layer I and the conductive shielding layer II are made of a silicone rubber composite material doped with carbon nanoparticles, which is used to block external electric field interference.

[0011] Furthermore, the insulating layer I is used to isolate the electrode layer I from the conductive shielding layer I.

[0012] Furthermore, the insulating layer II is used to isolate the electrode layer II from the conductive shielding layer II.

[0013] Furthermore, the non-gradient friction layer does not have a gradient structure.

[0014] Furthermore, the non-gradient friction layer is made of a foam material.

[0015] Furthermore, the gradient friction layer includes N stacked friction material layers.

[0016] Wherein, the size of the nth friction material layer is larger than that of the (n - 1)th friction material layer. n = 1, 2,..., N. N ≥ 2.

[0017] Furthermore, the friction material layer is made of a silicone rubber material.

[0018] The technical effect of the present invention is beyond doubt. The present invention proposes a gradient hierarchical structure design, expands the linear range by responding to pressure in stages through layering, integrates a shielding layer to suppress interference, and optimizes materials and processes to improve stability and manufacturability. Description of the Drawings

[0019] Figure 1 It is a structural diagram of the device;

[0020] Figure 2 It is a physical diagram of the device;

[0021] Figure 3 It is a schematic diagram of the device;

[0022] Figure 4 They are the parameters of the pressure sensor;

[0023] Figure 5 is the output difference of the sensor with / without a shielding layer;

[0024] Figure 6 is the output difference of the sensor with / without a gradient stratification structure;

[0025] Figure 7 is the output performance of the sensor applied to an electric piano system;

[0026] In the figure, there are conductive shielding layer I1, insulating layer I2, electrode layer I3, electrode layer II5, insulating layer II6, conductive shielding layer II7, non-gradient friction layer 401 and gradient friction layer 402. Specific embodiments

[0027] The present invention will be further described below in conjunction with embodiments, but it should not be understood that the above-mentioned subject matter scope of the present invention is limited to the following embodiments. Without departing from the above technical idea of the present invention, various substitutions and changes made according to common technical knowledge and customary means in the art shall be included within the protection scope of the present invention.

[0028] Embodiment 1:

[0029] See Figures 1 to 7 , a triboelectric pressure sensor with a gradient stratification structure, comprising a conductive shielding layer I1, an insulating layer I2, an electrode layer I3, a friction layer, an electrode layer II5, an insulating layer II6, and a conductive shielding layer II7 stacked in sequence.

[0030] The friction layer includes a non-gradient friction layer 401 and a gradient friction layer 402.

[0031] Two surfaces of the non-gradient friction layer 401 are respectively in contact with the gradient friction layer 402 and the electrode layer I3.

[0032] The gradient friction layer 402 has a gradient stratification structure.

[0033] Two surfaces of the gradient friction layer 402 are respectively in contact with the electrode layer II5 and the non-gradient friction layer 401.

[0034] The triboelectric pressure sensor realizes pressure grading detection through the contact and separation of the non-gradient friction layer 401 and the gradient friction layer 402.

[0035] When an external pressure is applied, the surfaces of the gradient friction layer 402 in contact with the non-gradient friction layer 401 carry positive and negative charges respectively due to the triboelectric effect. During the contact process between the gradient friction layer and the non-gradient friction layer, due to the principle of electrostatic induction, driving charges are transferred between the electrode layer I and the electrode layer II through an external circuit.

[0036] The conductive shielding layer I1 and the conductive shielding layer II7 are both made of a silicone rubber composite material doped with carbon nanoparticles, which is used to block external electric field interference.

[0037] The insulating layer I2 is used to isolate the electrode layer I3 from the conductive shielding layer I1.

[0038] The insulating layer II6 is used to isolate the electrode layer II5 from the conductive shielding layer II7.

[0039] The non-gradient friction layer 401 does not have a gradient structure.

[0040] The non-gradient friction layer 401 is made of a foam material.

[0041] The gradient friction layer 402 includes N stacked friction material layers.

[0042] Among them, the size of the nth friction material layer is larger than that of the (n - 1)th friction material layer. n = 1, 2,..., N. N ≥ 2.

[0043] The friction material layer is made of a silicone rubber material.

[0044] Example 2:

[0045] A triboelectric pressure sensor with a gradient hierarchical structure includes a conductive shielding layer I1, an insulating layer I2, an electrode layer I3, a friction layer, an electrode layer II5, an insulating layer II6, and a conductive shielding layer II7 stacked in sequence.

[0046] The friction layer includes a non-gradient friction layer 401 and a gradient friction layer 402.

[0047] The two surfaces of the non-gradient friction layer 401 are respectively in contact with the gradient friction layer 402 and the electrode layer I3.

[0048] The gradient friction layer 402 has a gradient hierarchical structure.

[0049] The two surfaces of the gradient friction layer 402 are respectively in contact with the electrode layer II5 and the non-gradient friction layer 401.

[0050] Example 3:

[0051] A triboelectric pressure sensor with a gradient hierarchical structure has the same technical content as in Example 2. Further, the triboelectric pressure sensor realizes pressure grading detection through the contact and separation of the non-gradient friction layer 401 and the gradient friction layer 402.

[0052] Example 4:

[0053] A triboelectric pressure sensor with a gradient hierarchical structure, the technical content being the same as any one of Embodiments 2-3. Further, when an external pressure is applied, the surfaces of the gradient friction layer 402 and the non-gradient friction layer 401 in contact carry positive and negative charges respectively due to the triboelectric effect. During the contact process between the gradient friction layer and the non-gradient friction layer, due to the principle of electrostatic induction, driving charges transfer between the electrode layer I and the electrode layer II through an external circuit.

[0054] Embodiment 5:

[0055] A triboelectric pressure sensor with a gradient hierarchical structure, the technical content being the same as any one of Embodiments 2-4. Further, both the conductive shielding layer I1 and the conductive shielding layer II7 are made of a silicone rubber composite doped with carbon nanoparticles, which is used to block external electric field interference.

[0056] Embodiment 6:

[0057] A triboelectric pressure sensor with a gradient hierarchical structure, the technical content being the same as any one of Embodiments 2-5. Further, the insulating layer I2 is used to isolate the electrode layer I3 from the conductive shielding layer I1.

[0058] Embodiment 7:

[0059] A triboelectric pressure sensor with a gradient hierarchical structure, the technical content being the same as any one of Embodiments 2-6. Further, the insulating layer II6 is used to isolate the electrode layer II5 from the conductive shielding layer II7.

[0060] Embodiment 8:

[0061] A triboelectric pressure sensor with a gradient hierarchical structure, the technical content being the same as any one of Embodiments 2-7. Further, the non-gradient friction layer 401 does not have a gradient structure.

[0062] Embodiment 9:

[0063] A triboelectric pressure sensor with a gradient hierarchical structure, the technical content being the same as any one of Embodiments 2-8. Further, the non-gradient friction layer 401 is made of a foam material.

[0064] Embodiment 10:

[0065] A triboelectric pressure sensor with a gradient hierarchical structure, the technical content being the same as any one of Embodiments 2-9. Further, the gradient friction layer 402 includes N stacked friction material layers.

[0066] Among them, the size of the nth friction material layer is larger than that of the (n - 1)th friction material layer. n = 1, 2,..., N. N ≥ 2.

[0067] Embodiment 11:

[0068] A triboelectric pressure sensor with a gradient hierarchical structure, the technical content is the same as any one of Embodiments 2-10. Further, the friction material layer is made of silicone rubber material.

[0069] Embodiment 12:

[0070] A triboelectric pressure sensor with a gradient hierarchical structure is as follows:

[0071] As Figure 1 shown, from the outside to the inside of the sensor are a conductive shielding layer (pink), an insulating layer (upper and lower blue layers), an electrode layer (black), and a friction layer (stepped blue and gray). The top and bottom shielding layers are made of a silicone rubber composite doped with carbon nanoparticles to block external electric field interference; silicone rubber is used as the insulating layer to isolate the electrodes from the shielding layer; the middle gradient friction layer is silicone rubber with a gradient hierarchical structure, and the other friction layer is a foam layer. Through the staged response of each gradient layer during the contact-separation process, pressure grading detection is achieved.

[0072] As Figure 2 shown, the two carbon fibers above and below are connected to the shielding layer, and the carbon fibers on the left and right are connected to the electrode layer.

[0073] Carbon fiber wires are used to conduct out electrical signals. Traditional metal wires are relatively hard, do not meet the requirements of flexible wearability, and there is poor contact between the rigid material and the carbon-doped silica gel. Carbon fiber wires are composed of many filaments, and the carbon-doped silica gel can firmly adhere to them during the solidification process.

[0074] The device principle is as Figure 3 shown. During the contact-separation process between the gradient friction layer and the foam, electrical signals are generated through electrostatic induction. When an external pressure is applied, the contact surfaces of the silicone rubber and the foam carry positive and negative charges respectively due to the triboelectric effect. When the silicone rubber and the foam are in contact, due to the principle of electrostatic induction, driving charges transfer between electrode layer I and electrode layer II through the external circuit. Thanks to the gradient structure of the friction layer, during the contact pressing process, different degrees of external excitation will cause a more obvious potential distribution difference, thereby improving the sensing sensitivity of the device.

[0075] Figure 4 (a) is the pressure sensing sensitivity curve graph of friction layers with different gradient structures (four, three, two layers) and no structure (single layer) under the same conditions. It can be seen that the sensitivity of the gradient structure friction layer (purple, yellow, red) is significantly better than that of the friction layer without structure (light blue), and the response curve of the three-layer gradient structure is the best; Figure 4 (b) is the real-time voltage response curve of the sensor under different vertical external forces applied by a linear motor; Figure 4(c) shows the output signals of the sensor in different bending states. It can be seen from the figure that bending has little effect on the sensing performance, demonstrating the flexibility and bendability of the sensor and proving the application potential of the sensor in the field of flexible pressure sensing such as human wearables; Figure 4 (d) shows the response time test of the sensor at 8 kPa, indicating that the sensor has a very fast response speed; Figure 4 (e) shows the output voltage signals of the sensor under different humidity conditions. It can be seen from the figure that due to the closed structure of the sensor, the output voltage is insensitive to humidity and will not affect voltage sensing; Figure 4 (f) shows the durability test of the sensor. After the sensor worked under a cyclic pressure of 27 kPa for 2.5 h, there was no obvious decrease in the voltage output before and after.

[0076] During the operation of the triboelectric pressure sensor, the change in electric potential mainly stems from the induced electric potential generated by the frictional charges accumulated on the electrode surface. However, external charged objects can also generate induced electric potential on the induction electrode, thus interfering with the sensing signal. These two kinds of induced electric potentials interfere with each other, affecting the accuracy of the sensor output. To reduce this interference, the device is designed with carbon-doped silica gel layers on the top and bottom surfaces as shielding layers. This design ensures that external objects can only induce charges on the shielding layer, thus preventing interference with the internal induction electrode. Figure 5 (i) shows the schematic diagram of the structure of the device without a shielding layer. When the hand approaches but no pressure is applied, the upper electrode will generate induced charges, resulting in voltage signal fluctuations, as Figure 5 (ii) shows. This situation makes it impossible for the triboelectric pressure sensor to distinguish external interference (such as the approach of a charged object) from the applied pressure, thus unable to accurately monitor the pressure. In contrast, Figure 5 (iii) shows the schematic diagram of the structure of the device with a shielding layer. When the hand approaches but no pressure is applied, induced charges are only generated on the shielding layer. This mechanism effectively shields the influence of external interference on the induction electrode, preventing the device from generating voltage signal fluctuations due to the action of interference electric potential without contact pressure, as Figure 5 (iv) shows.

[0077] To verify the role of the gradient structure in characterizing the pressing process, by controlling the parameters of the linear motor, the same force is applied to the devices with / without the gradient structure, as Figure 6 (i) and (iii) show. It can be seen that for the flexible sensor without the gradient structure, during the pressing process, the change in the contact area between the interfaces is a continuous process, and the voltage signal shows as a continuous pulse signal, as Figure 6(ii). In contrast, for the pressure sensor with a multi-layer gradient structure, the contact area changes discretely as the pressing progresses, resulting in a stepped increase in the amplitude of the output signal during the pressing process, as shown in Figure 6 (iv). Figure 7 Shows a practical application scenario of the sensor: a flexible wearable triboelectric piano. Four sensors are used as the key inputs of the piano, and the sound intensity, sound duration, and pitch of the piano are reflected by the voltage amplitude, the interval time between positive and negative peak values, and the sensor channels. Figure 7 (a) Shows that the sensor successfully realizes the pressure grading detection in the piano keys (from piano to forte); Figure 7 (b) Shows the response curves of the sensor under different pressing durations. When the sensor receives pressure, a reverse pulse is generated, and when the pressure is released, the sensor generates a forward pulse again. The dwell time of the finger on the key can be judged by the interval time between the two pulses. In addition, the high response speed of the sensor can ensure timely sound production during dynamic performance; Figure 7 (c) Shows that no crosstalk occurs between different closely arranged channels, thus realizing the functions of playing different pitches and chords on the piano.

Claims

1. A triboelectric pressure sensor with a gradient hierarchical structure, characterized in that: It includes a conductive shielding layer I (1), an insulating layer I (2), an electrode layer I (3), a friction layer, an electrode layer II (5), an insulating layer II (6), and a conductive shielding layer II (7) that are stacked in sequence; The friction layer includes a non-gradient friction layer (401) and a gradient friction layer (402); Two surfaces of the non-gradient friction layer (401) are respectively in contact with the gradient friction layer (402) and the electrode layer I (3); The gradient friction layer (402) is a gradient layered structure; Two surfaces of the gradient friction layer (402) are respectively in contact with the electrode layer II (5) and the non-gradient friction layer (401).

2. The triboelectric pressure sensor with a gradient hierarchical structure according to claim 1, characterized in that: The triboelectric pressure sensor realizes pressure grading detection through the contact and separation of the non-gradient friction layer (401) and the gradient friction layer (402).

3. The triboelectric pressure sensor with a gradient hierarchical structure according to claim 1, characterized in that: When an external pressure is applied, the surfaces of the gradient friction layer (402) and the non-gradient friction layer (401) in contact carry positive and negative charges respectively due to the triboelectrification effect; During the contact process of the gradient friction layer and the non-gradient friction layer, due to the principle of electrostatic induction, driving charges are transferred between the electrode layer I and the electrode layer II through an external circuit.

4. The triboelectric pressure sensor with a gradient hierarchical structure according to claim 1, wherein: Both the conductive shielding layer I (1) and the conductive shielding layer II (7) adopt a silicone rubber composite material doped with carbon nanoparticles to block external electric field interference.

5. A triboelectric pressure sensor with a gradient hierarchical structure according to claim 1, characterized in that: The insulating layer I (2) is used to isolate the electrode layer I (3) from the conductive shielding layer I (1).

6. The triboelectric pressure sensor with a gradient hierarchical structure according to claim 1, wherein: The insulating layer II (6) is used to isolate the electrode layer II (5) from the conductive shielding layer II (7).

7. A triboelectric pressure sensor with a gradient hierarchical structure according to claim 1, characterized in that: The non-gradient friction layer (401) does not have a gradient structure.

8. The triboelectric pressure sensor with a gradient hierarchical structure according to claim 1, characterized in that: The non-gradient friction layer (401) adopts a foam material.

9. The triboelectric pressure sensor with a gradient hierarchical structure according to claim 1, wherein: The gradient friction layer (402) includes N stacked friction material layers; Among them, the size of the nth friction material layer is larger than that of the (n - 1)th friction material layer; n = 1, 2,..., N; N ≥ 2.

10. The triboelectric pressure sensor with a gradient hierarchical structure according to claim 7, wherein: The friction material layer adopts a silicone rubber material.

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