Passive pressure sensor based on piezoelectric potential enhanced triboelectric effect and preparation method thereof

Abstract

The present invention discloses a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect, comprising: an electrode layer, a flexible polymer material layer, a ZnO wrinkle layer, a ZnO nanowire layer and a negative polarity friction layer; wherein the thickness of ZnO deposited when making the ZnO wrinkle layer is 10nm-1μm, the thermal expansion coefficients of the flexible polymer material and ZnO used to make the flexible polymer material layer are not matched, and the top crystal plane of ZnO in the ZnO nanowire layer is a (0001) crystal plane. The pressure sensor provided by the present invention has higher sensitivity.

Description

Technical Field

[0001] The present invention belongs to the field of pressure sensors, and in particular relates to a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of the Internet of Things (IoT) and artificial intelligence (AI), pressure sensing electronic devices with precise mechanical perception capabilities have attracted increasing attention in the fields of human-machine interface systems, artificial skin and prostheses, and robotics. Although various pressure sensors based on transistor, piezoresistive, and capacitive effects have been developed, these electronic devices are heavily dependent on external power sources such as batteries and solar cells. Due to the limited capacity and short life of batteries, solar cells are susceptible to environmental constraints, which inevitably affects the long-term stable operation of pressure sensors.

[0003] To overcome this problem, the emerging triboelectric nanogenerator (TENG) technology has been widely used to develop self-driven passive pressure sensing systems. Its excellent electromechanical response performance, simple structure, low cost and easy transplantation make TENG-based passive pressure sensors (TPS for short) show broad application prospects.

[0004] In the prior art, the surface charge density is increased by constructing micro / nano structures on the surface of the friction layer; for example, introducing surface structures such as monotonous micro / nano cones, cylinders, pyramids, porous structures, or fine hierarchical micro / nano structures on the surface of the friction material can improve the sensitivity of TPS by increasing the interface roughness and stress concentration effect.

[0005] However, the sensitivity of existing TPS is still low, which seriously limits its wide application in human-machine interface systems, artificial skin and prostheses. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention provides a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect and a preparation method thereof.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0008] A passive pressure sensor based on piezoelectric potential enhanced triboelectric effect, comprising:

[0009] Electrode layer;

[0010] A flexible polymer material layer; the flexible polymer material layer is located on the electrode layer;

[0011] ZnO wrinkled layer; the ZnO wrinkled layer is located on the flexible polymer material layer;

[0012] ZnO nanowire layer; the ZnO nanowire layer is located on the ZnO wrinkle layer;

[0013] A negative polarity friction layer; the negative polarity friction layer is located on the ZnO nanowire layer;

[0014] The thickness of ZnO deposited when making the ZnO wrinkle layer is 10nm-1μm, the thermal expansion coefficients of the flexible polymer material and ZnO used to make the flexible polymer material layer do not match, and the top crystal plane of ZnO in the ZnO nanowire layer is the (0001) crystal plane.

[0015] Optionally, it further comprises: a spacer;

[0016] The spacer is located between the negative polarity friction layer and the ZnO nanowire layer, and occupies a smaller area than the ZnO nanowire layer.

[0017] Optionally, the flexible polymer material includes polydimethylsiloxane (PDMS).

[0018] Optionally, the material of the negative-polarity friction layer includes: fluorinated ethylene propylene copolymer FEP.

[0019] Optionally, the electrode layer includes: a substrate and a conductive layer located on the substrate;

[0020] The material of the conductive layer includes: indium tin oxide ITO;

[0021] The material of the substrate includes: polyethylene terephthalate PET.

[0022] The present invention also provides a method for preparing a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect, comprising:

[0023] Spin coating a flexible polymer material on the electrode layer to form a flexible polymer material layer; the thermal expansion coefficients of the flexible polymer material in the flexible polymer material layer and ZnO do not match;

[0024] Depositing a ZnO layer with a thickness of 10 nm to 1 μm on the flexible polymer material layer, and then cooling the layer to form a ZnO wrinkle layer on the flexible polymer material layer;

[0025] Growing ZnO nanowires on the ZnO wrinkled layer to form a ZnO nanowire layer;

[0026] A negative-polarity friction layer is pasted on the ZnO nanowire layer to obtain a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect;

[0027] Wherein, the top crystal plane of ZnO in the ZnO nanowire layer is a (0001) crystal plane.

[0028] Optionally, it also includes:

[0029] Before pasting the negative-polarity friction layer on the ZnO nanowire layer, a spacer is placed on the ZnO nanowire layer, and the area occupied by the spacer is smaller than that of the ZnO nanowire layer.

[0030] Optionally, a layer of ZnO with a thickness of 10 nm to 1 μm is deposited on the flexible polymer material layer, comprising:

[0031] A ZnO layer with a thickness of 10 nm to 1 μm is deposited on the flexible polymer material layer by using a magnetron sputtering process.

[0032] Optionally, growing ZnO nanowires on the ZnO wrinkled layer comprises:

[0033] ZnO nanowires are grown on the ZnO wrinkled layer using a room temperature hydrothermal method.

[0034] Optionally, the height of the ZnO nanowires in the ZnO nanowire layer is 10 nm to 50 μm.

[0035] The passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by the present invention has a layered wrinkle structure formed by a ZnO wrinkle layer + a ZnO nanowire layer. The layered wrinkle structure with piezoelectric effect can generate a macroscopic piezoelectric potential under the action of external pressure, effectively regulating the potential barrier height (electric effect) of the interface between the negative polarity friction layer, thereby effectively promoting the separation of friction charges and increasing the surface friction charge density. This electric effect enhancement strategy can be used in conjunction with the negative polarity friction layer to greatly improve the pressure detection sensitivity of TPS, thereby enabling TPS to be widely used in the fields of human-machine interface systems, artificial skin and prostheses.

[0036] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1( a ) is a schematic cross-sectional view of a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by an embodiment of the present invention;

[0038] FIG. 1( b ) is a perspective view of the passive pressure sensor shown in FIG. 1( a );

[0039] Figure 2 is a schematic diagram of the use of a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by an embodiment of the present invention;

[0040] Figure 3Schematic diagram of the working principle of a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by an embodiment of the present invention;

[0041] Figure 4 Schematic diagram of the working mechanism of a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by an embodiment of the present invention;

[0042] Figure 5 is a schematic structural diagram of another passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by an embodiment of the present invention;

[0043] Figure 6 and Figure 7 The experimental results of Experiment 1 carried out to verify the beneficial effects of the passive pressure sensor provided by the embodiment of the present invention are respectively shown;

[0044] Figure 8(a) to Figure 8(d) 1 and 2 show the experimental results of Experiment 2 carried out to verify the beneficial effects of the passive pressure sensor provided by the embodiment of the present invention;

[0045] Fig. 9 is a flow chart of a method for preparing a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by an embodiment of the present invention;

[0046] Fig.10 yes Fig. 9 a graphical flow chart of the method shown;

[0047] Figure 11(a) to Figure 11(c) They are shown respectively Fig. 9 Scanning electron micrographs of the various layer structures prepared in the illustrated method. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0049] In order to further improve the sensitivity of TPS, an embodiment of the present invention provides a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect, as shown in FIG1( a), the pressure sensor includes: an electrode layer, a flexible polymer material layer, a ZnO wrinkle layer, a ZnO nanowire layer and a negative polarity friction layer.

[0050] Figure 1(b) shows a stereoscopic view of the passive pressure sensor in Figure 1(a). Combining Figure 1(a) and Figure 1(b), it can be seen that the passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided in an embodiment of the present invention is a TPS in a single electrode working mode.

[0051] The electrode layer includes: a substrate and a conductive layer located on the substrate. The material of the conductive layer may include: ITO (indium tin oxide), or it may also be a common metal electrode material, such as copper, aluminum, etc. The thickness of the electrode layer is 30μm to 1mm, for example, 50μm. The material of the substrate may include: PET (polyethylene terephthalate); or it may also be other substrates with a certain rigidity, such as silicon wafers, glass, polystyrene, etc.

[0052] The flexible polymer material layer is located on the electrode layer; the flexible polymer material used to make the flexible polymer material layer may include PDMS (polydimethylsiloxane), PU (polyurethane) or ecoflex (copolyester), etc. Any flexible polymer material that does not match the thermal expansion coefficient of ZnO can be used to prepare the flexible polymer material layer. The thickness of the flexible polymer material layer is 1 μm to 3 mm, for example, 50 μm.

[0053] The ZnO wrinkle layer is located on the flexible polymer material layer. The thickness of the deposited ZnO when the ZnO wrinkle layer is made is 10nm-1μm.

[0054] The inventors have found through experiments that when the thickness of the deposited ZnO is less than 10nm, it is not enough to form wrinkles, and when the thickness of the deposited ZnO is greater than 1μm, the local shrinkage effect cannot be achieved due to the excessive thickness of ZnO, resulting in the wrinkles not being obvious enough. Therefore, depositing 10nm to 1μm ZnO can produce a better ZnO wrinkle layer.

[0055] The ZnO nanowire layer is located on the ZnO wrinkle layer; the height of the ZnO nanowire is 10nm to 50μm.

[0056] In the embodiment of the present invention, the ZnO wrinkle layer imitates the wrinkles of human fingers and can perceive external mechanical stimulation with high precision. Therefore, the ZnO layered wrinkle structure formed after growing the ZnO nanowire layer using this wrinkle structure as the seed layer has a higher perception sensitivity to external mechanical stimulation.

[0057] In the embodiment of the present invention, ZnO is a wurtzite-type ZnO material, and the top crystal plane of ZnO in the ZnO nanowire layer is a (0001) crystal plane.

[0058] The negative friction layer is located on the ZnO nanowire layer; the material of the negative friction layer may include: FEP (fluorinated ethylene propylene copolymer), PTFE (fluorinated ethylene propylene copolymer), PI (polyimide) or PET (polyethylene terephthalate), etc. The thickness of the negative friction layer is 1 μm to 300 μm.

[0059] In practical applications, external pressure is applied to the pressure sensor (such as Figure 2As shown), the electrode layer of the pressure sensor outputs the pressure sensed by the pressure sensor in the form of an electrical signal.

[0060] The working mechanism of the passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by the embodiment of the present invention is as follows:

[0061] like Figure 3 As shown, the ZnO layered wrinkle structure and the negative polarity friction layer ( Figure 3 According to the triboelectric sequence, electrons are transferred from ZnO to the negative polarity friction layer, leaving an equal amount of positive charges on the top of the ZnO layered wrinkle structure, such as Figure 3 As shown in sub-figure I in Figure 1, due to the layered wrinkle structure, only a small amount of ZnO nanowires are in contact with the negative friction layer at first. Therefore, all the pressure is concentrated in a small area, giving the TPS a high sensitivity. When the ZnO layered wrinkle structure is compressed, a piezoelectric potential is generated along the length of the ZnO nanowire, which enhances the triboelectric effect between the negative friction layer and ZnO, as shown in Figure 2. Figure 3 As shown in sub-figure II in Figure 2, when a higher external force is applied to the ZnO layered wrinkle structure, a large deformation and a high voltage potential are achieved. At the same time, more ZnO nanowires located on the wrinkles with different heights are in contact with the negative friction layer, and more electrons are transferred from ZnO to the negative friction layer, as shown in Figure 2. Figure 3 As shown in sub-figure III in Figure 3. After the pressure is removed, the potential distribution between the negative polarity friction layer and ZnO is as follows: Figure 3 As shown in sub-figure IV.

[0062] For more details, see Figure 4 The charge distribution and corresponding charge transfer process in the electron cloud potential well model shown in the figure: When the negative friction layer ( Figure 4 When the negative polarity friction layer (represented by FEP in the figure) rubs against the ZnO layered wrinkle structure, the piezoelectric potential generated by the deformation of the ZnO layered wrinkle structure will be coupled to the separation process of the friction charge during the contact charging process. Initially, the negative polarity friction layer and ZnO are close to each other, but there is still a distance between them, which hinders the transfer of friction charge between them. When the negative polarity friction layer and ZnO are just in contact, due to the "shielding" effect between the two materials in physical contact, the electron clouds partially overlap, and the initial single potential well becomes an asymmetric double potential well. Electrons occupying specific atomic orbitals in ZnO tend to move to lower empty orbitals in the negative polarity friction layer, and the number of electrons transferred is proportional to the difference in potential well depth between the two materials (surface potential difference). Then, when pressure is applied to the negative polarity friction layer and the ZnO layered wrinkle structure, the electrons move along the crystal plane direction (from the negative polarity friction layer to ZnO) pointing to the ZnO. Figure 3 0001 in the figure) generates a piezoelectric potential V piezo, and the potential well of ZnO is lifted upward. As a result, more electrons will be transferred from ZnO to the negative polarity friction layer until a new equilibrium is reached.

[0063] Theoretically, based on the above-mentioned working mechanism, the unique layered wrinkled structure in the embodiment of the present invention combined with the piezoelectric potential-enhanced triboelectric effect is effective in improving the sensitivity of TPS and expanding its working range.

[0064] The passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by the present invention has a layered wrinkle structure formed by a ZnO wrinkle layer + a ZnO nanowire layer. The layered wrinkle structure with piezoelectric effect can generate a macroscopic piezoelectric potential under the action of external pressure, effectively regulating the potential barrier height (electric effect) of the interface between the negative polarity friction layer, thereby effectively promoting the separation of friction charges and increasing the surface friction charge density. This electric effect enhancement strategy can be used in conjunction with the negative polarity friction layer to greatly improve the pressure detection sensitivity of TPS, thereby enabling TPS to be widely used in the fields of human-machine interface systems, artificial skin and prostheses.

[0065] In one embodiment, Figure 5 As shown, the passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by an embodiment of the present invention may also include: a spacer; the spacer is located between the negative polarity friction layer and the ZnO nanowire layer, and occupies an area smaller than the ZnO nanowire layer.

[0066] It can be understood that the role of the spacer is to isolate the negative polarity friction layer from the ZnO nanowire layer by a certain distance, thereby reducing the background noise of the pressure sensor without external pressure. Therefore, in practice, the area occupied by the spacer is much smaller than the area of ​​the ZnO nanowire layer, and it only needs to play a certain spacing role.

[0067] In practical applications, the spacer may be polyurethane foam, but is certainly not limited thereto.

[0068] Preferably, the spacer can be attached to the four corners of the ZnO nanowire layer, respectively, with a height of about 5 mm; of course, it is not limited thereto.

[0069] The beneficial effects of the embodiments of the present invention are described below through experimental data.

[0070] Experiment 1: Prepare TPS with an electrode layer of ITO film, a flexible polymer material layer of PDMS, and a negative friction layer of FEP film. In addition, a polyurethane foam spacer is placed between the ZnO nanowire layer and the negative friction layer.

[0071] According to the non-centrosymmetric structure and piezoelectric properties of wurtzite ZnO materials, Kelvin probe force microscopy was used to analyze the piezoelectric properties of wurtzite ZnO materials at positive potential. (ZnO crystal plane is (0001) crystal plane), negative voltage potential (The crystal plane of ZnO is (000-1) crystal plane) and zero piezoelectric potential (The crystal plane of ZnO is the (10-10) crystal plane) The surface potential changes when the FEP film is rubbed against the ZnO layered wrinkle structure.

[0072] For details, see Figure 6 as well as Figure 7 As shown, at negative potential In the case of the friction between the FEP film and the ZnO layered wrinkle structure surface under different pressures (0kPa, 10kPa, 20kPa, 100kPa), the surface potential of the FEP film dropped sharply, from the initial value of -360mV (0kPa) to -6.34V (100kPa). In the case of positive potential, the surface potential of the FEP film only decreased from -360 mV (0 Pa) to -4.84 V (100 kPa). In the case of , the surface potential of the FEP film only decreased from -360 mV (0 Pa) to -3.29 V (100 kPa), respectively.

[0073] Among them, since the lower negative surface potential means that more electrons are captured by FEP from ZnO, the negative piezoelectric potential generated by ZnO enhances the triboelectric effect between FEP and ZnO, while the positive piezoelectric potential weakens it. Adjusting the triboelectric effect is an effective way to improve the sensitivity of TPS, especially in the large pressure area, where the piezoelectric potential will be higher and the regulation will be more effective.

[0074] Experiment 2: Referring to the TPS prepared in Experiment 1, a TPS with only a single layer of ZnO wrinkled layer was prepared and its performance was verified. The experimental results showed that the charge density was 5.56nC / cm at pressures of 10kPa, 20kPa and 100kPa respectively. 2 (nanocoulomb / cm2), 6.15nC / cm 2 and 6.64nC / cm 2. Comparing the performance of the TPS with the ZnO layered wrinkle structure in Experiment 1, it can be seen that when the pressure increases from 10 kPa to 20 kPa and 100 kPa, the charge density of the TPS with the ZnO layered wrinkle structure increases by 50.9% and 151%, respectively, which are 4.8 times and 7.8 times of the TPS with a single-layer ZnO wrinkle layer, respectively, and are significantly larger than the TPS with a single-layer ZnO wrinkle layer. This proves the effective charge separation and transfer ability of the ZnO layered wrinkle structure in the embodiment of the present invention, indicating that the TPS with the ZnO layered wrinkle structure in the embodiment of the present invention has higher sensitivity.

[0075] Experiment 2: The TPS prepared in Experiment 1 and Experiment 2 were subjected to sensitivity tests.

[0076] Specifically, the TPS sensitivity is calculated based on the applied force / pressure and the output voltage measured from the electrode layer. As shown in Figure 8(a), the pressure sensitivity of TPS can be divided into two regions: a low-pressure region (<25kPa) and a high-pressure region (25-476kPa); among them, the TPS with a single-layer ZnO wrinkle layer has a pressure sensitivity K of only 1.06V / kPa and 0.06V / kPa in the two regions, respectively. In contrast, the TPS with a layered wrinkle structure has a sensitivity K of 4.14V / kPa and 0.25V / kPa in the two regions, respectively, which is 2.91 times and 3 times higher than the former, respectively. It can be seen that the embodiment of the present invention, while effectively improving the sensitivity of TPS, will hardly reduce the modulus of the sensing layer, and therefore shows a good balance between high sensitivity and a wide detection range (up to 476kPa).

[0077] FIG8( b ) shows that the TPS with a layered corrugated structure can generate an electrical response to external mechanical stimulation in real time. FIG8( c ) shows the response time of the TPS. It can be seen that the response time is only about 28 ms.

[0078] In addition, several existing TPSs and the TPS with a layered corrugated structure provided by an embodiment of the present invention were selected, and their pressure-sensitivity relationship curves were analyzed; as shown in Figure 8(d), it can be seen that the TPS with a layered corrugated structure provided by an embodiment of the present invention has obvious advantages in terms of both sensitivity and detection range, which illustrates that the design concept of the pressure-enhanced triboelectric effect (electric effect) and the layered corrugated structure (mechanical effect) in the embodiment of the present invention are compatible, and the electrical and mechanical effects are combined, which is very beneficial to improving the sensitivity of the TPS and giving the TPS a wider detection range.

[0079] Based on the same inventive concept, the embodiment of the present invention also provides a method for preparing the passive pressure sensor based on piezoelectric potential enhanced triboelectric effect, such as Fig. 9As shown, the method comprises the following steps:

[0080] S10: spin coating a flexible polymer material on the electrode layer to form a flexible polymer material layer; the thermal expansion coefficients of the flexible polymer material in the flexible polymer material layer and ZnO do not match.

[0081] For example, 10 parts per unit mass of PDMS prepolymer can be weighed, and then 1 part per unit mass of curing agent can be added, stirred and mixed for 10 minutes, and ultrasonicated for 5 minutes to remove bubbles to obtain a PDMS prepolymer solution (mass ratio of substrate to cross-linking curing agent is 10:1). Then, a 50 μm thick PDMS film is spin-coated on a 50 μm thick ITO or PET film by spin coating, and a flexible polymer material layer is formed after curing at 80°C for 30 minutes.

[0082] Alternatively, equal weights of components A and B of ecoflex were weighed, stirred for 5 min until fully mixed, and ultrasonicated for 5 min to remove bubbles. Ecoflex film was prepared by spin coating, and cured at 80 degrees for 20 min to obtain a flexible polymer material layer.

[0083] Alternatively, polyurethane can be weighed and dissolved in DMF (N,N-dimethylformamide) (e.g. 1 g PU, 3 g DMF), stirred for 30 min until completely dissolved, a PU film can be prepared by spin coating, and the solvent can be dried at 60 degrees for 1 h to obtain a flexible polymer material layer.

[0084] Fig.10 Sub-figure II in FIG. 1 shows a schematic diagram of preparing a flexible polymer material layer; FIG. 11( a ) shows a scanning electron micrograph of the prepared flexible polymer material layer.

[0085] S20: depositing a ZnO layer with a thickness of 10 nm to 1 μm on the flexible polymer material layer, and then cooling the layer to form a ZnO wrinkled layer on the flexible polymer material layer.

[0086] Specifically, this step can use a magnetron sputtering process to deposit ZnO on the flexible polymer material layer. Among them, the sputtering power can be 100W, and the air pressure is 0.5Pa, but it is certainly not limited to this. After sputtering ZnO, cooling is carried out. The cooling time can be calculated according to the specific sputtered ZnO thickness. When specifically calculating, the cooling time can be estimated according to the thickness of 2nm per minute. After cooling is completed according to the estimated time, due to the mismatch in the thermal expansion coefficients of the flexible polymer material and ZnO in the flexible polymer material layer, the top surface of the hybrid structure formed by the two tends to shrink locally, and a layer of wrinkled structure can be spontaneously formed on the flexible polymer material layer, that is, a ZnO wrinkled layer is formed.

[0087] Fig.10Sub-figure II in the figure shows a schematic diagram of the preparation of the ZnO wrinkled layer, and sub-figure III shows a schematic diagram after the ZnO wrinkled layer is prepared; Figure 11(b) shows a scanning electron micrograph after the ZnO wrinkled layer is prepared, and it can be seen that the ZnO wrinkles are at the micron level.

[0088] S30: growing ZnO nanowires on the ZnO wrinkle layer to form a ZnO nanowire layer; the top crystal plane of ZnO in the ZnO nanowire layer is a (0001) crystal plane.

[0089] Specifically, a room temperature hydrothermal method is used to grow ZnO nanowires on the ZnO wrinkle layer.

[0090] For example, 0.08 g of NaOH and 0.0325 g of ZnO can be dissolved in 40 mL of deionized water and stirred continuously for 10 minutes to obtain a transparent precursor solution. Subsequently, the flexible polymer material layer and the ZnO wrinkled layer grown together are completely immersed in the solution to grow ZnO nanowires at room temperature. Then, the layer is taken out and washed with deionized water, and dried at 65° C. for 30 minutes to form a ZnO nanowire layer.

[0091] Fig.10 Sub-figure IV in FIG. 11 shows a schematic diagram of preparing a ZnO nanowire layer; FIG. 11( c ) shows a scanning electron micrograph of the prepared ZnO nanowire layer. It can be seen that the ZnO nanowires grow with the wrinkles prepared in step S20 as the seed layer, forming a special structure with two different levels of ups and downs at the micrometer and nanometer levels.

[0092] S40: Pasting a negative polarity friction layer on the ZnO nanowire layer to obtain a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect.

[0093] Optionally, in one implementation, the method for preparing a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect provided by an embodiment of the present invention may further include:

[0094] Before pasting the negative polarity friction layer on the ZnO nanowire layer, a spacer is placed on the ZnO nanowire layer, and the area occupied by the spacer is smaller than that of the ZnO nanowire layer.

[0095] For example, polyurethane foam with a height of 5 mm can be attached to the four corners of the ZnO nanowire layer, and then the FEP film is attached on top of the polyurethane foam.

[0096] The embodiment of the present invention does not limit the size of the passive pressure sensor provided, and in practice it can be specifically designed according to the usage scenario.

[0097] It should be noted that, for the preparation method embodiment, since the dimensions and material parameters of each layer structure prepared therein have been described in detail in the passive pressure sensor embodiment, the description in the preparation method embodiment is relatively simple, and the relevant details may refer to the description in the passive pressure sensor embodiment.

[0098] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0099] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0100] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0101] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the drawings and the disclosed content.

[0102] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A passive pressure sensor based on piezoelectric potential enhanced triboelectric effect, characterized in that: include: Electrode layer; A flexible polymer material layer; the flexible polymer material layer is located on the electrode layer; ZnO wrinkled layer; the ZnO wrinkled layer is located on the flexible polymer material layer; ZnO nanowire layer; the ZnO nanowire layer is located on the ZnO wrinkle layer; Negative polarity friction layer; The negative polarity friction layer is located on the ZnO nanowire layer; The thickness of ZnO deposited when making the ZnO wrinkle layer is 10nm-1μm, the thermal expansion coefficients of the flexible polymer material and ZnO used to make the flexible polymer material layer do not match, and the top crystal plane of ZnO in the ZnO nanowire layer is a (0001) crystal plane; The ZnO wrinkle layer and the ZnO nanowire layer form a layered wrinkle structure; the layered wrinkle structure is prepared by the following method: Depositing a layer of ZnO with a thickness of 10 nm to 1 μm on the flexible polymer material layer, and then cooling the layer, wherein the cooling time is calculated according to the thickness of the deposited ZnO, so that the top surface of the hybrid structure formed by the flexible polymer material layer and the ZnO tends to shrink locally, and the ZnO wrinkled layer is spontaneously formed on the flexible polymer material layer; Using the ZnO wrinkle layer as a seed layer, growing ZnO nanowires on the ZnO wrinkle layer to form a ZnO nanowire layer located on wrinkles with different heights; The ZnO wrinkled layer senses external mechanical stimulation by imitating wrinkles on human fingers, and the ZnO layered wrinkled structure formed by growing a ZnO nanowire layer using the ZnO wrinkled layer as a seed layer can have a higher sensitivity to external mechanical stimulation.

2. The passive pressure sensor based on piezoelectric potential enhanced triboelectric effect according to claim 1, characterized in that: Also includes: spacers; The spacer is located between the negative polarity friction layer and the ZnO nanowire layer, and occupies a smaller area than the ZnO nanowire layer.

3. The passive pressure sensor based on piezoelectric potential enhanced triboelectric effect according to claim 1, characterized in that: The flexible polymer material includes: polydimethylsiloxane (PDMS).

4. The passive pressure sensor based on piezoelectric potential enhanced triboelectric effect according to claim 1, characterized in that: The material of the negative-polarity friction layer includes: fluorinated ethylene propylene copolymer FEP.

5. The passive pressure sensor based on piezoelectric potential enhanced triboelectric effect according to claim 1, characterized in that: The electrode layer comprises: a substrate and a conductive layer located on the substrate; The material of the conductive layer includes: indium tin oxide ITO; The material of the substrate includes: polyethylene terephthalate PET.

6. A method for preparing a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect, characterized in that: include: Spin coating a flexible polymer material on the electrode layer to form a flexible polymer material layer; the thermal expansion coefficients of the flexible polymer material in the flexible polymer material layer and ZnO do not match; Depositing a layer of ZnO with a thickness of 10 nm to 1 μm on the flexible polymer material layer, and then cooling the layer to form a ZnO wrinkle layer on the flexible polymer material layer; wherein the cooling time is calculated according to the thickness of the deposited ZnO, so that the top surface of the hybrid structure formed by the flexible polymer material layer and the ZnO tends to shrink locally, and the ZnO wrinkle layer is spontaneously formed on the flexible polymer material layer; The ZnO wrinkle layer is used as a seed layer, and ZnO nanowires are grown on the ZnO wrinkle layer to form a ZnO nanowire layer located on wrinkles of different heights; the ZnO wrinkle layer and the ZnO nanowire layer form a layered wrinkle structure; wherein the ZnO wrinkle layer senses external mechanical stimulation by imitating wrinkles of human fingers, and the ZnO layered wrinkle structure formed after the ZnO nanowire layer is further grown using the ZnO wrinkle layer as a seed layer can have a higher sensitivity to external mechanical stimulation; A negative-polarity friction layer is pasted on the ZnO nanowire layer to obtain a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect; Wherein, the top crystal plane of ZnO in the ZnO nanowire layer is a (0001) crystal plane.

7. The method for preparing a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect according to claim 6, characterized in that: Also includes: Before pasting the negative-polarity friction layer on the ZnO nanowire layer, a spacer is placed on the ZnO nanowire layer, and the area occupied by the spacer is smaller than that of the ZnO nanowire layer.

8. The method for preparing a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect according to claim 6, characterized in that: Depositing a ZnO layer with a thickness of 10 nm to 1 μm on the flexible polymer material layer, comprising: A ZnO layer with a thickness of 10 nm to 1 μm is deposited on the flexible polymer material layer by using a magnetron sputtering process.

9. The method for preparing a passive pressure sensor based on piezoelectric potential enhanced triboelectric effect according to claim 6, characterized in that: Growing ZnO nanowires on the ZnO wrinkled layer, comprising: ZnO nanowires are grown on the ZnO wrinkled layer using a room temperature hydrothermal method.

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