A flexible sensor based on oxide wrinkle structure and its preparation method

Abstract

The present invention discloses a flexible sensor based on an oxide wrinkle structure and a preparation method thereof, comprising: using a solid-phase method to prepare a Sr3Al2O6 target material and a La-BaTiO3 target material respectively; using a pulsed laser deposition technique to prepare a "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure using the Sr3Al2O6 target material and the BaTiO3 target material on a SrTiO3 single crystal substrate; using a water-soluble method to electrostatically adsorb a polydimethylsiloxane (PDMS) film on the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure. The La-BaTiO3 film was then peeled off from the structure to create a "La-BaTiO3 / PDMS" heterostructure. A gold (Au) electrode was grown on the "La-BaTiO3 / PDMS" heterostructure using magnetron sputtering to create an "Au / PDMS / La-BaTiO3" heterostructure. Another PDMS film was attached to the Au electrode surface of the "Au / PDMS / La-BaTiO3" heterostructure by electrostatic adsorption for encapsulation, resulting in a piezoresistive sensor with the "PDMS / Au / La-BaTiO3 / PDMS" heterostructure. This preparation method offers high process controllability, and the resulting flexible piezoresistive sensor exhibits high precision, high sensitivity, and high reliability. The flexible piezoresistive sensor can adapt to changes in various surfaces and shapes and has a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the field of, but is not limited to, flexible sensor technology, and in particular to a flexible sensor based on an oxide wrinkle structure and a preparation method thereof. Background Art

[0002] As a key component of sensors, piezoresistive sensors are widely used in aviation, chemical engineering, navigation, power generation, and medical fields. These devices can convert pressure information such as force, air pressure, and hydraulic pressure into electrical signals. Piezoresistive sensors primarily consist of an active layer, electrodes, and an encapsulation layer. The active layer, as the core of the piezoresistive sensor, exhibits a significant change in resistance when subjected to pressure. Oxide-based semiconductors, a typical active layer material, are widely used in piezoresistive sensors due to their excellent piezoresistive coefficients.

[0003] However, with the continuous development of integrated, miniaturized, and complex portable detection devices, existing oxide-based semiconductor active layers, either rigid or grown on rigid substrates, are no longer able to meet the flexible application requirements of piezoresistive sensors. Current solutions use metal-based or carbon-based nanomaterials as active layers. While these materials can achieve resistance adjustment through percolation theory and the tunneling effect, the use of low-resistivity materials reduces sensor sensitivity, increasing the risk of irreversible damage.

[0004] Therefore, how to apply rigid piezoresistive active layer materials to the preparation of flexible devices will be an important breakthrough in optimizing the performance of flexible piezoresistive sensors in the future. Summary of the Invention

[0005] Purpose of the present invention: In order to solve the above-mentioned technical problems, the embodiments of the present invention provide a flexible sensor based on an oxide wrinkle structure and a preparation method thereof, so as to solve the problem that the existing rigid piezoresistive active layer materials cannot be applied to flexible piezoresistive sensors, and to solve the problem that the existing solutions using metal-based nanomaterials or carbon-based nanomaterials as active layers will cause the sensor sensitivity to decrease, thereby increasing the probability of irreversible damage.

[0006] Technical solution of the present invention: In a first aspect, an embodiment of the present invention provides a method for preparing a flexible sensor based on an oxide wrinkle structure, the method comprising the following steps:

[0007] Step 1: Prepare Sr3Al2O6 ceramic target by solid phase method;

[0008] Step 2: Prepare La using solid phase method 3+ Ion-doped BaTiO3 ceramic target, namely La-BaTiO3 ceramic target;

[0009] Step 3: Using pulsed laser deposition technology, on a SrTiO3 single crystal substrate with a (100) orientation, a "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure is prepared using the Sr3Al2O6 ceramic target and the La-BaTiO3 ceramic target;

[0010] Step 4: electrostatically adsorbing a polydimethylsiloxane (PDMS) film onto the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure using a water-soluble method, peeling off the La-BaTiO3 film from the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure, and preparing a "La-BaTiO3 / PDMS" heterostructure with a wrinkled structure;

[0011] Step 5: growing a gold Au electrode on the "La-BaTiO3 / PDMS" heterostructure with a wrinkled structure by magnetron sputtering to prepare a "PDMS / La-BaTiO3 / Au" heterostructure;

[0012] Step 6: Attach another PDMS membrane to the Au electrode surface of the "Au / La-BaTiO3 / PDMS" heterostructure by electrostatic adsorption for encapsulation to obtain a piezoresistive sensor of the "PDMS / Au / La-BaTiO3 / PDMS" heterostructure.

[0013] Optionally, in the method for preparing a flexible sensor based on an oxide wrinkle structure as described above, step 1 comprises:

[0014] Step 1.1, accurately weigh SrCO3 powder and Al2O3 powder according to the molar ratio of Sr to Al of 3:2 as raw material 1;

[0015] Step 1.2, weighing ball stone and alcohol in a mass ratio of raw material 1: ball stone: alcohol = 1:2:2, mixing, ball milling, and sieving, placing the sieved mixture in a constant temperature drying oven to dry, to prepare a uniformly mixed powder of raw material 1; wherein the drying temperature is 80°C and the drying time is 24 hours;

[0016] Step 1.3, placing the raw material 1 mixed with the powder into a crucible, and calcining in an air atmosphere to synthesize Sr3Al2O6 powder; wherein the calcination temperature is 1200°C and the holding time is 4 hours;

[0017] Step 1.4, weighing the ball stone and alcohol in a mass ratio of Sr3Al2O6 powder: ball stone: alcohol = 1:2:2, mixing, ball milling, and sieving, placing the sieved mixture in a constant temperature drying oven to dry, to prepare a fine Sr3Al2O6 powder after powder refinement; wherein the drying temperature is 80°C and the drying time is 24 hours;

[0018] Step 1.5, granulating and tableting the refined Sr3Al2O6 fine powder to prepare Sr3Al2O6 formed discs;

[0019] Step 1.6: sinter the Sr3Al2O6 formed disc in an air atmosphere at a sintering temperature of 1400°C for 4 hours to prepare a Sr3Al2O6 ceramic target.

[0020] Optionally, in the preparation method of the flexible sensor based on the oxide wrinkle structure as described above, when granulating and tableting the Sr3Al2O6 fine powder after the powder is refined in step 1.5, 10% polyvinyl alcohol adhesive is used, and the particle diameter of the Sr3Al2O6 fine powder after granulation is between 0.11-0.18 mm; the diameter of the prepared Sr3Al2O6 molded disc is 30 mm and the thickness is 5 mm.

[0021] Optionally, in the method for preparing a flexible sensor based on an oxide wrinkle structure as described above, step 2 comprises:

[0022] Step 2.1, accurately weigh BaCO3 powder and TiO2 powder according to the molar ratio of Ba to Ti element of 1:1 as raw material 2;

[0023] Step 2.2, weighing ball stone and alcohol in a mass ratio of raw material 2: ball stone: alcohol = 1:2:2, mixing, ball milling, and sieving, placing the sieved mixture in a constant temperature drying oven to dry, to prepare a uniformly mixed powder of raw material 2; wherein the drying temperature is 80°C and the drying time is 24 hours;

[0024] Step 2.3, placing the raw material 2 mixed with the powder into a crucible, and calcining in an air atmosphere to synthesize BaTiO3 powder; wherein the calcination temperature is 1000°C and the holding time is 2h;

[0025] Step 2.4, accurately weighing the BaTiO3 powder and La2O3 powder according to the molar ratio of Ba to La of 100:3 as raw material 3;

[0026] Step 2.5, weighing ball stone and alcohol in a mass ratio of raw material 3: ball stone: alcohol = 1:2:2, mixing, ball milling, and sieving, placing the sieved mixture in a constant temperature drying oven to dry, to prepare a uniformly mixed powder of raw material 3; wherein the drying temperature is 80°C and the drying time is 24 hours;

[0027] Step 2.6, granulating and tableting the raw material 3 with the powder mixed evenly to prepare a shaped round tablet of the raw material 3;

[0028] Step 2.7: Place the formed disc of raw material 3 in an atmosphere furnace and sinter to obtain a La-BaTiO3 ceramic target; wherein the sintering atmosphere is hydrogen, the sintering temperature is 1200°C, and the temperature is kept for 2 hours.

[0029] Optionally, in the method for preparing a flexible sensor based on an oxide wrinkle structure as described above, step 3 includes:

[0030] Step 3.1, using pulsed laser deposition technology, on a SrTiO3 single crystal substrate with a (100) orientation, using the Sr3Al2O6 ceramic target prepared in step 1 to prepare a "Sr3Al2O6 / SrTiO3" heterostructure; wherein the temperature of the SrTiO3 single crystal substrate is 800°C, and the distance between the Sr3Al2O6 target and the SrTiO3 single crystal substrate is 6 cm;

[0031] Step 3.2: Using pulsed laser deposition technology, on the "Sr3Al2O6 / SrTiO3" heterostructure, the La-BaTiO3 ceramic target is prepared using the step 2 to prepare a "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure; wherein the temperature of the SrTiO3 single crystal substrate is 800°C, and the distance between the La-BaTiO3 target and the SrTiO3 single crystal substrate is 6 cm.

[0032] Optionally, in the above-mentioned method for preparing a flexible sensor based on an oxide wrinkle structure, in the process of preparing the "Sr3Al2O6 / SrTiO3" heterostructure by pulsed laser deposition technology in step 3.1, the laser energy is 2J / cm 2 , laser frequency is 3 Hz, oxygen partial pressure is 15 Pa, and growth time is 5 min.

[0033] Optionally, in the process of preparing the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure by pulsed laser deposition technology in step 3.2, the laser energy is 2J / cm 2 , laser frequency is 3 Hz, nitrogen partial pressure is 15 Pa, and growth time is 5 min.

[0034] Optionally, in the method for preparing a flexible sensor based on an oxide wrinkle structure as described above, step 4 includes:

[0035] Step 4.1, attaching a PDMS film to the surface of the La-BaTiO3 layer of the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure by electrostatic adsorption to obtain a "PDMS / La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure;

[0036] Step 4.2: Place the "PDMS / La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure in deionized water and let it stand for 24 hours to dissolve the Sr3Al2O6 film. Remove the obtained "La-BaTiO3 / PDMS" heterostructure from the deionized water and dry it at 60°C for 30 minutes to finally obtain the "La-BaTiO3 / PDMS" heterostructure.

[0037] Optionally, in the method for preparing a flexible sensor based on an oxide wrinkle structure as described above, the thickness of the PDMS film in step 4.1 is 50 μm; and when the PDMS film is attached by electrostatic adsorption, a tensile stress of 5% is applied to the PDMS film.

[0038] Optionally, in the preparation method of the flexible sensor based on the oxide wrinkle structure as described above, the thickness of the Au electrode grown on the "La-BaTiO3 / PDMS" heterostructure with the wrinkle structure in step 5 is 50 nm, and the test area of ​​the Au electrode is 100 μm×100 μm.

[0039] In a second aspect, an embodiment of the present invention further provides a flexible sensor based on an oxide wrinkle structure, wherein the flexible sensor is prepared using the method for preparing a flexible sensor based on an oxide wrinkle structure as described in any one of the above items; the flexible sensor comprises: a PDMS encapsulation layer, an Au electrode layer, and a La-BaTiO3 active layer;

[0040] The flexible sensor is provided with the following layers in order from top to bottom: a PDMS packaging layer, an Au electrode layer, a La-BaTiO3 active layer and a PDMS packaging layer.

[0041] Optionally, in the flexible sensor based on the oxide wrinkle structure as described above, the La-BaTiO3 active layer is a wrinkle structure; the test area of ​​the positive and negative electrodes in the Au electrode layer is 100μm×100μm; and the positive and negative electrodes of the Au electrode layer are used to measure the surface resistance of the wrinkle structure La-BaTiO3 active layer.

[0042] Beneficial effects of the present invention: The embodiment of the present invention provides a flexible sensor based on an oxide wrinkle structure and a preparation method thereof, the preparation method comprising: preparing a Sr3Al2O6 ceramic target by a solid phase method; preparing a La 3+ Ion-doped BaTiO3 ceramic target, namely La-BaTiO3 ceramic target; pulsed laser deposition technology is used on a SrTiO3 single crystal substrate with a crystal orientation of (100), according to the Sr3Al2O6 ceramic target and the La - BaTiO3 ceramic target material was used to prepare a "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure; a PDMS film was electrostatically adsorbed on the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure by a water-soluble method, and the La-BaTiO3 film in the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure was peeled off, and a "La-BaTiO3 / A flexible piezoresistive sensor with a "PDMS / Au / La-BaTiO3 / PDMS" heterostructure is prepared. An Au electrode is grown on the wrinkled "La-BaTiO3 / PDMS" heterostructure using magnetron sputtering to obtain an "Au / La-BaTiO3 / PDMS" heterostructure. Another PDMS membrane is attached to the Au electrode surface of the "Au / La-BaTiO3 / PDMS" heterostructure by electrostatic adsorption for encapsulation to obtain a piezoresistive sensor with a "PDMS / Au / La-BaTiO3 / PDMS" heterostructure. This preparation method has high process controllability and a simple preparation process. The resulting flexible piezoresistive sensor has the characteristics of high precision, high sensitivity, and high reliability. The flexible piezoresistive sensor can adapt to changes in various surfaces and shapes and has a wide range of applications.

[0043] The flexible sensor based on an oxide wrinkle structure provided in an embodiment of the present invention is prepared using any of the methods for preparing a flexible sensor based on an oxide wrinkle structure described above. The flexible sensor includes: a PDMS encapsulation layer, an Au electrode layer, and a La-BaTiO3 active layer. The flexible sensor is arranged in the following order from top to bottom: a PDMS encapsulation layer, an Au electrode layer, a La-BaTiO3 active layer, and a PDMS encapsulation layer. The sensor can adapt to changes in various surfaces and shapes, has a wide range of applicability, is applicable to applications requiring a compact design, and has the characteristics of high precision and high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0045] Figure 1 A front view of the structure of a flexible sensor prepared by the method for preparing a flexible sensor based on an oxide wrinkle structure provided by an embodiment of the present invention;

[0046] Figure 2 A top view of the structure of a flexible sensor prepared by the method for preparing a flexible sensor based on an oxide wrinkle structure provided by an embodiment of the present invention;

[0047] Figure 3 Schematic diagram of the change in resistance of a flexible sensor prepared by the method for preparing a flexible sensor based on an oxide wrinkle structure provided by an embodiment of the present invention when a pressure of 0.001N is applied multiple times. DETAILED DESCRIPTION

[0048] To make the purpose, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other in any manner.

[0049] The following is a schematic illustration of the implementation of the flexible sensor based on the oxide wrinkle structure and the preparation method thereof provided by the present invention through several specific embodiments.

[0050] Example 1

[0051] The present invention provides a method for preparing a flexible sensor based on an oxide wrinkle structure, the method comprising the following steps:

[0052] Step 101: Prepare a Sr3Al2O6 ceramic target material by a solid phase method. The specific process is as follows:

[0053] Step 101-1, accurately weighing SrCO3 powder and Al2O3 powder according to the molar ratio of Sr to Al of 3:2 as raw material 1;

[0054] Step 101-2, weighing ball stone and alcohol in a mass ratio of raw material 1: ball stone: alcohol = 1:2:2, placing raw material 1, ball stone, and alcohol in a polytetrafluoroethylene ball mill at a speed of 300 r / min for 4 hours, and after the ball milling is completed, placing the mixed solution after the ball stone in the ball mill jar through screening in a constant temperature drying oven at a drying temperature of 80°C for a drying time of 24 hours to prepare a uniformly mixed powder of raw material 1;

[0055] Step 101-3: Place the uniformly mixed raw material 1 into a crucible and calcine in an air atmosphere at a temperature of 1200° C. for 4 hours to obtain Sr3Al2O6 powder;

[0056] Step 101-4, weighing the ball stone and alcohol in a mass ratio of Sr3Al2O6 powder: ball stone: alcohol = 1:2:2, placing the Sr3Al2O6 powder, ball stone, and alcohol in a polytetrafluoroethylene ball mill at a speed of 300 r / min for 4 hours, after the ball milling is completed, removing the mixed solution from the ball mill after the ball stone is sieved and drying it in a constant temperature drying oven at 80°C for 24 hours to prepare a refined Sr3Al2O6 fine powder;

[0057] Step 101-5: Place Sr3Al2O6 fine powder in an agate mortar and add 10% polyvinyl alcohol binder to granulate the powder. The diameter of the granulated particles is within the range of 0.11-0.18 mm.

[0058] Step 101-6: Place the granulated Sr3Al2O6 particles in a powder tablet press and press them into discs with a diameter of 30 mm and a thickness of 5 mm at a molding pressure of 10 MPa;

[0059] Step 101-7: Place the formed disc with a diameter of 30 mm and a thickness of 5 mm in an air atmosphere and sinter it at a sintering temperature of 1400° C. for 4 hours to prepare a Sr3Al2O6 ceramic target.

[0060] In step 101 of this embodiment, on the one hand, the Sr3Al2O6 target, as a ceramic material, can chemically react with water. This reaction process does not require catalysts such as strong acids or bases, making the reaction environmentally friendly and simple. On the other hand, when preparing the Sr3Al2O6 ceramic target using a solid-phase method in this technical solution, since the reaction process uses solid particles such as SrCO3 powder and Al2O3 powder, the product purity can be controlled by adjusting the reaction temperature and time, reducing reaction byproducts, and is more economical than some other advanced preparation methods.

[0061] Step 102: Prepare La by solid phase method 3+ Ion-doped BaTiO3 ceramic target is La-BaTiO3 ceramic target. The specific process is as follows:

[0062] Step 102-1, accurately weighing BaCO3 powder and TiO2 powder according to the molar ratio of Ba to Ti element of 1:1 as raw material 2;

[0063] Step 102-2, weighing ball stone and alcohol in a mass ratio of raw material 2: ball stone: alcohol = 1:2:2, placing raw material 2, ball stone, and alcohol in a polytetrafluoroethylene ball mill at 300 r / min for 4 hours, and after ball milling, drying the mixed solution after sieving the ball stone in the ball mill in a constant temperature drying oven at 80°C for 24 hours to prepare a uniformly mixed powder of raw material 2;

[0064] Step 102-3: Place the uniformly mixed raw material 2 into a crucible and calcine in an air atmosphere at a calcination temperature of 1000° C. for 2 h to synthesize BaTiO 3 powder;

[0065] Step 102-4, accurately weighing BaTiO3 powder and La2O3 powder according to the molar ratio of Ba to La of 100:3 as raw material 3;

[0066] Step 102-5, weighing ball stone and alcohol in a mass ratio of raw material 3: ball stone: alcohol = 1:2:2, placing raw material 3, ball stone, and alcohol in a polytetrafluoroethylene ball mill at a speed of 300 r / min for 4 hours, and after the ball milling is completed, placing the mixed solution after the ball stone in the ball mill jar through screening in a constant temperature drying oven at a drying temperature of 80°C for a drying time of 24 hours to prepare a uniformly mixed powder of raw material 3;

[0067] Step 102-6: Place the uniformly mixed powder of the raw material 3 in an agate mortar, and add 10% polyvinyl alcohol binder to granulate the particles. The diameter of the particles after granulation is within the range of 0.11-0.18 mm.

[0068] Step 102-7: Place the granulated raw material 3 in a powder tablet press to press into discs with a diameter of 30 mm and a thickness of 5 mm at a molding pressure of 10 MPa;

[0069] Step 102-8: Place the formed disc with a diameter of 30 mm and a thickness of 5 mm in a hydrogen atmosphere and sinter it at a sintering temperature of 1200° C. for 2 hours to prepare a La-BaTiO 3 ceramic target.

[0070] In the above step 102 of this embodiment, the La-BaTiO3 ceramic target material is a perovskite structure semiconductor having a lattice constant similar to that of Sr3Al2O6 and semiconductor resistive switching characteristics brought about by oxygen vacancies.

[0071] Furthermore, in the above steps 102-4 to 102-8 of this embodiment, La 3+ Ion doping of BaTiO3 powder with La2O3 as a dopant can modulate the resistive properties of the BaTiO3 ceramic target, such as increasing the oxygen vacancy content in the BaTiO3 crystals and thereby improving the electrical conductivity of the BaTiO3 ceramic target. It should be noted that in the present embodiment, the Ba and La elements are mixed in a molar ratio of 100:3, which is the preferred embodiment; the ratio can range from 100:3 to 100:10.

[0072] Step 103: Using pulsed laser deposition technology, a "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure is prepared on a SrTiO3 single crystal substrate with a (100) orientation. The specific process is as follows:

[0073] Step 103-1: Using pulsed laser deposition technology, grow a 20nm thick Sr3Al2O6 film on a (100)-oriented SrTiO3 single crystal substrate. The target used is the Sr3Al2O6 ceramic target prepared in the previous step. The temperature of the SrTiO3 single crystal substrate is 800°C. The distance between the Sr3Al2O6 target and the SrTiO3 single crystal substrate is 6cm. The laser energy is 2J / cm 2 , the laser frequency is 3 Hz, the oxygen partial pressure is 15 Pa, and the growth time is 5 min to prepare the "Sr3Al2O6 / SrTiO3" heterostructure;

[0074] Step 103-2: Using pulsed laser deposition technology, grow a 20nm thick La-BaTiO3 film on the "Sr3Al2O6 / SrTiO3" heterostructure. The target used is the La-BaTiO3 ceramic target prepared in the previous step. The temperature of the SrTiO3 single crystal substrate is 800°C. The distance between the La-BaTiO3 target and the SrTiO3 single crystal substrate is 6cm. The laser energy is 2J / cm 2 , laser frequency is 3 Hz, nitrogen pressure is 15 Pa, growth time is 5 min, and the “La-BaTiO3 / Sr3Al2O6 / SrTiO3” heterostructure is prepared.

[0075] In the above step 103 of this embodiment, when pulsed laser deposition technology is used to prepare the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure, this technology can ensure that the prepared film has good crystallinity and high density. Since the deposition materials of this heterostructure are directly derived from the Sr3Al2O6 ceramic target and the La-BaTiO3 target, the introduction of impurity-free materials can ensure a high degree of consistency between the film composition and the target composition. In addition, by controlling the laser energy, frequency, and deposition environment (atmosphere and atmospheric pressure), the growth process of the film can be precisely controlled. This controllability can finely adjust the thickness, morphology, grain size, etc. of the film.

[0076] Step 104: Using a water-soluble method, electrostatically adsorb the PDMS film onto the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure, and peel off the La-BaTiO3 film in the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure to prepare a "La-BaTiO3 / PDMS" heterostructure with a wrinkled structure. The detailed process is described as follows:

[0077] Step 104-1: Apply 5% tensile stress to a 50 μm thick PDMS film and attach it to the surface of the La-BaTiO3 layer of the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure by electrostatic adsorption to obtain the "PDMS / La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure;

[0078] Step 104-2: Place the "PDMS / La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure in deionized water and let it stand for 24 hours to dissolve the Sr3Al2O6 film. Remove the resulting "La-BaTiO3 / PDMS" heterostructure from the deionized water and dry it at 60°C for 30 minutes to obtain the "La-BaTiO3 / PDMS" heterostructure.

[0079] It should be understood that when the Sr3Al2O6 film is dissolved in deionized water, the Sr3Al2O6 film adheres to the SrTiO3 substrate, so the SrTiO3 substrate peels off from the "PDMS / La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure along with the Sr3Al2O6 film; when the Sr3Al2O6 film is dissolved in deionized water, the tensile stress of the PDMS film is released in the deionized water, which causes the La-BaTiO3 film to present a wrinkled structure due to the release of the tensile stress. For easier understanding, please refer to the attached Figure 1 Indicated in Figure 1 The front view of the structure of the flexible sensor prepared by the preparation method of the flexible sensor based on the oxide wrinkle structure; Figure 1 As shown, the La-BaTiO3 active layer can show the wrinkled structure; in this embodiment, the wrinkled structure of the La-BaTiO3 film is used as the oxide-based semiconductor active layer. Due to the characteristics of its own wrinkled structure and the fact that the La-BaTiO3 film can be flexibly stretched, it can meet the flexible application requirements of the piezoresistive sensor. Since the wrinkled structure of the La-BaTiO3 active layer is described in detail here, Figure 1The gold electrodes and PDMS encapsulation layer can be found in the description of the subsequent steps. Furthermore, in step 104, the "La-BaTiO3 / PDMS" heterostructure is prepared by a water-soluble method, which is relatively simple to operate, has relatively mild reaction conditions, and has strong controllability.

[0080] Step 105: A gold electrode is grown on the "PDMS / La-BaTiO3" heterostructure with a wrinkled structure by magnetron sputtering to prepare an "Au / La-BaTiO3 / PDMS" heterostructure. The specific process is as follows:

[0081] A metal mask with a hollowed-out electrode pattern was affixed to the surface of a La-BaTiO3 film. A 50nm-thick Au electrode was then grown in a magnetron sputtering apparatus. Finally, the mask was removed from the La-BaTiO3 film to create an "Au / La-BaTiO3 / PDMS" heterostructure with a specific electrode pattern. The Au electrode test area was 100μm x 100μm.

[0082] It's important to understand that the role of the Au electrode within the La-BaTiO3 / PDMS heterostructure is that the 50nm-thick Au film ensures the conductivity of the current transport layer while maintaining the sensor's flexibility. The reliability of the flexible sensor is ensured by carefully designing the thickness of the Au electrode and the test area within the flexible sensor.

[0083] Step 106: attach another 50 μm thick PDMS film to the surface of the Au electrode by electrostatic adsorption for packaging, thereby obtaining a piezoresistive sensor with a “PDMS / Au / La-BaTiO 3 / PDMS” heterostructure.

[0084] In order to understand the "PDMS / Au / La-BaTiO3 / PDMS" heterostructure prepared in the embodiment of the present invention, please refer to the attached Figure 1 and attached Figure 2 Attached Figure 1 and attached Figure 2 Schematic diagram of the piezoresistive sensor of the “PDMS / La-BaTiO3 / Au / PDMS” heterostructure observed from different angles. Figure 1 The structural front view of the flexible sensor prepared by the preparation method of the flexible sensor based on the oxide wrinkle structure, Figure 2 This is a top view of the structure of a flexible sensor prepared by the preparation method of a flexible sensor based on an oxide wrinkle structure.

[0085] like Figure 1As shown in the figure, the "PDMS / Au / La-BaTiO3 / PDMS" piezoresistive sensor is a multi-layer structure composed of different materials. From the order of the structural presentation of each layer:

[0086] First, the La-BaTiO3 active layer with a wrinkled structure is used as an oxide-based semiconductor active layer and is arranged in the middle layer position of the above-mentioned multi-layer structure piezoresistive sensor. The wrinkled La-BaTiO3 active layer is a soft material that can adapt to changes in various surfaces and shapes in a complex working environment. Since the wrinkled La-BaTiO3 active layer is a flexible material with piezoresistive properties, its own resistance value can change significantly when subjected to external force. Secondly, an Au electrode layer is provided on one side of the La-BaTiO3 active layer with a wrinkled structure, and the electrode layer is composed of positive and negative Au electrodes. The Au electrode layer serves as a resistance sensing layer and can measure the resistance change of the wrinkled La-BaTiO3 active layer in the test area and convert the resistance before and after the change into a voltage or current signal. Finally, the PDMS layer is provided as an encapsulation layer on the outermost side of the above-mentioned piezoresistive sensor to provide protection support and pressure conduction for the piezoresistive sensor as a whole.

[0087] like Figure 2 As shown in the attached Figure 2 From the top view of the flexible piezoresistive sensor, the PDMS layer is the outermost layer of the piezoresistive sensor layer structure. Since the PDMS layers prepared in the embodiments of the present invention are all 50 μm thick, the PDMS layer has good transparency. The highly transparent PDMS layer allows the internal Au electrode layer and the wrinkled La-BaTiO3 active layer to be directly seen from the top view. Figure 2 In the image, a test area (100 μm × 100 μm) located between the positive and negative Au electrodes can be directly observed. It should be understood that this test area is the wrinkled La-BaTiO3 active layer located between the positive and negative Au electrodes.

[0088] In this embodiment, the positive and negative Au electrodes measure the surface resistance of the test area of ​​the wrinkled La-BaTiO3 active layer. Surface resistance refers to the resistance value per unit area on the surface of a material. Since surface resistance can detect small pressure changes, it is suitable for piezoresistive sensors with high sensitivity requirements. Of course, the flexible resistance sensor of the embodiment of the present invention also adjusts the position of the positive and negative Au electrodes to test the corresponding body resistance (adjust the positive and negative Au electrodes to Figure 1The positive and negative Au electrodes are positioned opposite each other on the PDMS layers on different sides of the La-BaTiO3 active layer. Bulk resistance refers to the resistance per unit volume within a material. Generally, changes in surface resistance at equal pressures are more significant than changes in bulk resistance. (When the La-BaTiO3 active layer is thin, the resistance change near the surface due to external deformation is typically greater than that within the material.) Changes in surface resistance can better reflect local deformation, allowing piezoresistive sensors to detect more subtle spatial changes, making resistance changes easier to measure.

[0089] As an optional implementation, the piezoresistive sensor of the embodiment of the present invention preferably selects the aforementioned surface resistance testing method.

[0090] In order to verify the performance of the flexible sensor based on the oxide wrinkle structure prepared in the embodiment of the present invention, the prepared flexible sensor was subjected to a performance verification experiment. Figure 3 The hint, Figure 3 A schematic diagram shows the change in resistance of a flexible sensor provided by an embodiment of the present invention when a pressure of 0.001 N is repeatedly applied. As shown, when a pressure of 0.001 N is applied to the flexible sensor at a preset frequency, the internal resistance of the sensor exhibits periodic changes, with significant changes compared to its initial state, demonstrating good sensitivity and cyclic stability.

[0091] Here, the working principle of the flexible sensor based on the oxide wrinkle structure prepared in this embodiment of the invention is detailed: When a pressure of 0.001N is applied to the flexible sensor, the PDMS encapsulation layer deforms due to the applied pressure, causing the wrinkled structure of the La-BaTiO3 active layer to expand and contract. As the wrinkled La-BaTiO3 active layer itself expands and contracts, its resistance also changes. The positive and negative Au electrodes on one side of the La-BaTiO3 active layer serve as resistance sensing layers, measuring the resistance change of the wrinkled La-BaTiO3 active layer within the test area and converting the resistance before and after the change into a voltage or current signal.

[0092] From the perspective of device preparation, the flexible sensor based on the oxide wrinkle structure of the embodiment of the present invention uses solid particles such as SrCO3 powder, Al2O3 powder, BaCO3 powder, TiO2 powder, and La2O3 powder as raw materials, and its reaction process is highly controllable. From the perspective of the flexible sensor prepared, the flexible piezoresistive sensor has high precision, high sensitivity, and high reliability; the flexible piezoresistive sensor can adapt to changes in various surfaces and shapes and has a wide range of applications, such as electronic skin. Because the La-BaTiO3 oxide wrinkle structure is designed as a thin layer material, it can reduce the overall weight of the piezoresistive sensor, making the device lightweight and portable, and therefore suitable for applications requiring a compact design.

[0093] Example 2

[0094] An embodiment of the present invention provides a flexible sensor based on an oxide wrinkle structure, comprising: a PDMS encapsulation layer, an Au electrode layer, and a La-BaTiO3 active layer; wherein the flexible sensor is provided in the following order from top to bottom: the PDMS encapsulation layer, the Au electrode layer, the La / BaTiO3 active layer, and the PDMS encapsulation layer;

[0095] Furthermore, the La-BaTiO3 active layer has a wrinkled structure, and the test area of ​​the positive and negative electrodes in the Au electrode layer is 100 μm×100 μm; and the positive and negative electrodes of the Au electrode layer are used to measure the surface resistance of the wrinkled La-BaTiO3 active layer;

[0096] In an optional embodiment, the thickness of the PDMS encapsulation layer is 50 μm. In the embodiment of the present invention, the PDMS layer is used as an encapsulation layer and is disposed on the outermost side of the flexible piezoresistive sensor to provide protection and support for the entire piezoresistive sensor and to conduct pressure.

[0097] In an optional embodiment, the Au electrode layer is a 50 nm thick thin film. In the embodiment of the present invention, the thickness of the Au electrode layer is set to 50 nm, which ensures the conductivity of the current transport layer without affecting the flexibility of the sensor.

[0098] The flexible sensor based on an oxide wrinkle structure according to an embodiment of the present invention can be obtained according to the preparation method provided in the first embodiment. Its operating principle is as follows: when external force is applied to the flexible sensor, the PDMS encapsulation layer deforms due to the applied pressure, thereby causing the wrinkle-like structure of the La-BaTiO3 active layer to expand and contract. When the wrinkle-like La-BaTiO3 active layer itself expands and contracts, its resistance value also changes accordingly. The positive and negative Au electrodes on one side of the La-BaTiO3 active layer serve as resistance sensing layers, measuring the resistance change of the wrinkle-like La-BaTiO3 active layer within the test area and converting the resistance before and after the change into a voltage or current signal.

[0099] The flexible sensor based on the oxide wrinkle structure of the embodiment of the present invention has the characteristics of high precision, high sensitivity and high reliability; the flexible piezoresistive sensor can adapt to changes in various surfaces and shapes, has a wide range of applications, and is applicable to applications requiring a compact design.

[0100] Although the embodiments disclosed herein are as described above, the contents are merely provided to facilitate understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art may make any modifications and variations in the form and details of the embodiments without departing from the spirit and scope of the present invention. However, the scope of patent protection of the present invention shall remain subject to the scope defined by the appended claims.

Claims

1. A method for preparing a flexible sensor based on an oxide wrinkle structure, characterized in that: The preparation method is carried out according to the following steps: Step 1: Prepare Sr3Al2O6 ceramic target by solid phase method; Step 2: Prepare La using solid phase method 3+ Ion-doped BaTiO3 ceramic target, namely La-BaTiO3 ceramic target; Step 3: Using pulsed laser deposition technology, on a SrTiO3 single crystal substrate with a (100) orientation, a "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure is prepared using the Sr3Al2O6 ceramic target and the La-BaTiO3 ceramic target; Step 4: Using a water-soluble method, electrostatically adsorbing a polydimethylsiloxane (PDMS) film onto the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure, and peeling off the La-BaTiO3 film from the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure to obtain a "La-BaTiO3 / PDMS" heterostructure with a wrinkled structure; Step 5: growing a gold electrode on the "La-BaTiO3 / PDMS" heterostructure with a wrinkled structure by magnetron sputtering to prepare an "Au / La-BaTiO3 / PDMS" heterostructure; Step 6: Another PDMS film is attached to the Au electrode surface of the "Au / La-BaTiO3 / PDMS" heterostructure by electrostatic adsorption for encapsulation to obtain a piezoresistive sensor of the "PDMS / Au / La-BaTiO3 / PDMS" heterostructure.

2. The method for preparing a flexible sensor based on an oxide wrinkle structure according to claim 1, characterized in that: The step 1 comprises: Step 1.1, accurately weigh SrCO3 powder and Al2O3 powder according to the molar ratio of Sr to Al of 3:2 as raw material 1; Step 1.2, weighing ball stone and alcohol in a mass ratio of raw material 1: ball stone: alcohol = 1:2:2, mixing, ball milling, and sieving, placing the sieved mixture in a constant temperature drying oven to dry, to prepare a uniformly mixed powder of raw material 1; wherein the drying temperature is 80°C and the drying time is 24 hours; Step 1.3, placing the raw material 1 mixed with the powder into a crucible, and calcining in an air atmosphere to synthesize Sr3Al2O6 powder; wherein the calcination temperature is 1200°C and the holding time is 4 hours; Step 1.4, weighing the ball stone and alcohol in a mass ratio of Sr3Al2O6 powder: ball stone: alcohol = 1:2:2, mixing, ball milling, and sieving, placing the sieved mixture in a constant temperature drying oven to dry, to prepare a fine Sr3Al2O6 powder after powder refinement; wherein the drying temperature is 80°C and the drying time is 24 hours; Step 1.5, granulating and tableting the refined Sr3Al2O6 fine powder to prepare Sr3Al2O6 formed discs; Step 1.6: sinter the Sr3Al2O6 formed disc in an air atmosphere at a sintering temperature of 1400°C for 4 hours to prepare a Sr3Al2O6 ceramic target.

3. The method for preparing a flexible sensor based on an oxide wrinkle structure according to claim 2, characterized in that: When the Sr3Al2O6 fine powder after the powder refinement is granulated and tableted in the step 1.5, 10% polyvinyl alcohol adhesive is used, and the particle diameter of the Sr3Al2O6 fine powder after granulation is between 0.11-0.18 mm; the diameter of the prepared Sr3Al2O6 formed disc is 30 mm and the thickness is 5 mm.

4. The method for preparing a flexible sensor based on an oxide wrinkle structure according to claim 1, characterized in that: The step 2 includes: Step 2.1, accurately weigh BaCO3 powder and TiO2 powder according to the molar ratio of Ba to Ti element of 1:1 as raw material 2; Step 2.2, weighing ball stone and alcohol in a mass ratio of raw material 2: ball stone: alcohol = 1:2:2, mixing, ball milling, and sieving, placing the sieved mixture in a constant temperature drying oven to dry, to prepare a uniformly mixed powder of raw material 2; wherein the drying temperature is 80°C and the drying time is 24 hours; Step 2.3, placing the raw material 2 mixed with the powder into a crucible, and calcining in an air atmosphere to synthesize BaTiO3 powder; wherein the calcination temperature is 1000°C and the holding time is 2h; Step 2.4, accurately weighing the BaTiO3 powder and La2O3 powder according to the molar ratio of Ba to La of 100:3 as raw material 3; Step 2.5, weighing ball stone and alcohol in a mass ratio of raw material 3: ball stone: alcohol = 1:2:2, mixing, ball milling, and sieving, placing the sieved mixture in a constant temperature drying oven to dry, to prepare a uniformly mixed powder of raw material 3; wherein the drying temperature is 80°C and the drying time is 24 hours; Step 2.6, granulating and tableting the raw material 3 with the powder mixed evenly to prepare a shaped round tablet of the raw material 3; Step 2.7: Place the formed disc of raw material 3 in an atmosphere furnace and sinter to obtain a dense La-BaTiO3 ceramic target; wherein the sintering atmosphere is hydrogen, the sintering temperature is 1200°C, and the temperature is kept for 2 hours.

5. The method for preparing a flexible sensor based on an oxide wrinkle structure according to claim 1, characterized in that: The step 3 comprises: Step 3.1, using pulsed laser deposition technology, on a SrTiO3 single crystal substrate with a (100) orientation, using the Sr3Al2O6 ceramic target prepared in step 1 to prepare a "Sr3Al2O6 / SrTiO3" heterostructure; wherein the temperature of the SrTiO3 single crystal substrate is 800°C, and the distance between the Sr3Al2O6 target and the SrTiO3 single crystal substrate is 6 cm; Step 3.2: Using pulsed laser deposition technology, on the "Sr3Al2O6 / SrTiO3" heterostructure, the La-BaTiO3 ceramic target is prepared using the step 2 to prepare a "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure; wherein the temperature of the SrTiO3 single crystal substrate is 800°C, and the distance between the La-BaTiO3 target and the SrTiO3 single crystal substrate is 6 cm.

6. The method for preparing a flexible sensor based on an oxide wrinkle structure according to claim 5, characterized in that: In the process of preparing the "Sr3Al2O6 / SrTiO3" heterostructure by pulsed laser deposition technology in step 3.1, the laser energy is 2J / cm 2 , laser frequency is 3 Hz, oxygen partial pressure is 15 Pa, and growth time is 5 min.

7. The method for preparing a flexible sensor based on an oxide wrinkle structure according to claim 5, characterized in that: In the process of preparing the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure by pulsed laser deposition technology in step 3.2, the laser energy is 2J / cm 2 , laser frequency is 3 Hz, nitrogen partial pressure is 15 Pa, and growth time is 5 min.

8. The method for preparing a flexible sensor based on an oxide wrinkle structure according to claim 1, characterized in that: The step 4 comprises: Step 4.1, attaching a PDMS film to the surface of the La-BaTiO3 layer of the "La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure by electrostatic adsorption to obtain a "PDMS / La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure; Step 4.2: Place the "PDMS / La-BaTiO3 / Sr3Al2O6 / SrTiO3" heterostructure in deionized water and let it stand for 24 hours to dissolve the Sr3Al2O6 film. Remove the obtained "La-BaTiO3 / PDMS" heterostructure from the deionized water and dry it at 60°C for 30 minutes to obtain the "La-BaTiO3 / PDMS" heterostructure.

9. The method for preparing a flexible sensor based on an oxide wrinkle structure according to claim 8, characterized in that: The thickness of the PDMS membrane in step 4.1 is 50 μm; when the PDMS membrane is attached by electrostatic adsorption, a tensile stress of 5% is applied to the PDMS membrane.

10. The method for preparing a flexible sensor based on an oxide wrinkle structure according to any one of claims 1 to 9, characterized in that: The thickness of the Au electrode grown on the "La-BaTiO 3 / PDMS" heterostructure with the wrinkled structure in step 5 is 50 nm, and the test area of ​​the Au electrode is 100 μm×100 μm.

11. A flexible sensor based on an oxide wrinkle structure, characterized in that: A flexible sensor based on an oxide wrinkle structure is prepared by the preparation method according to any one of claims 1 to 10; the flexible sensor comprises: a PDMS encapsulation layer, an Au electrode layer, and a La-BaTiO3 active layer; The flexible sensor is provided with the following layers in order from top to bottom: a PDMS packaging layer, an Au electrode layer, a La-BaTiO3 active layer and a PDMS packaging layer.

12. The flexible sensor based on oxide wrinkle structure according to claim 11, characterized in that: The La-BaTiO3 active layer has a wrinkled structure; The test area of ​​the positive and negative electrodes in the Au electrode layer is 100 μm×100 μm; and the positive and negative electrodes in the Au electrode layer are used to measure the surface resistance of the wrinkled structure La-BaTiO3 active layer.

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