Sucrose-based piezoelectric coating and sensor preparation method and application thereof

Abstract

The invention discloses a sucrose-based piezoelectric coating and a sensor preparation method and application thereof. The preparation method comprises the following steps: performing first heat treatment on a sucrose solution to obtain an amorphous sucrose film; and pressing the amorphous sucrose film to promote vertical growth of the seed crystal so as to obtain the sucrose-based piezoelectric coating. The columnar sucrose-based piezoelectric coating can be successfully prepared without large-scale film preparation equipment, the obtained sucrose-based piezoelectric coating has high crystallinity and good piezoelectric performance, meanwhile, based on the melting point of sucrose, the sucrose-based piezoelectric coating and the sensor thereof do not need to be prepared at a high temperature, and the preparation cost is low. The piezoelectric sensor can be formed on the surface of a material with poor temperature tolerance, and piezoelectric sensing detection is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric sensors, and particularly to a sucrose-based piezoelectric coating, a preparation method and an application thereof for sensors. Background Art

[0002] The preparation of piezoelectric thin films generally requires materials to have good film-forming properties and structural characteristics. At present, methods such as physical vapor deposition, molecular beam epitaxy, pulsed laser deposition, sol-gel method, and metal organic chemical vapor deposition have been successfully used to prepare piezoelectric thin films such as aluminum nitride, lead zirconate titanate, polyvinylidene fluoride, and lithium niobate. However, these methods are limited by the device or harsh preparation conditions, which also restricts the application of piezoelectric materials.

[0003] The crystal structure of sucrose is monoclinic, with high symmetry and weak polarization ability. When sucrose crystals are subjected to strong impact, instantaneous charges are generated due to deformation, but its piezoelectric effect is extremely weak and unreliable, unable to meet the technical requirements of piezoelectric materials (such as high piezoelectric response, stability, etc.). In addition, sucrose is prone to deliquescence and its physical properties are unstable. Therefore, sucrose cannot currently be used as a piezoelectric material, but it has the research prospect of becoming a piezoelectric material. It is necessary to stabilize the physical properties of sucrose, enhance the piezoelectricity of sucrose, and broaden the selection of piezoelectric materials and practical engineering applications through special treatment means.

[0004] However, in some limited studies, sucrose is only used as an additive to gelatin films. At the same time, the piezoelectric constant of sucrose is much lower than that of common piezoelectric materials. There are also studies indicating that the composite of sucrose with BaSO 4 / BaTiO 3 can enhance the piezoelectric catalytic activity, but its effect may stem from the chemical synergistic effect rather than the piezoelectric dominance of sucrose itself.

[0005] Currently, there is no research report on sucrose as a piezoelectric material and the preparation of sucrose columnar crystals. Based on the wide source of sucrose, it is necessary to study the preparation method of sucrose columnar crystals and optimize the performance of sucrose-based piezoelectric materials to expand their applications. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention successfully prepares a columnar sucrose-based piezoelectric coating by controlling the crystal seed growth of the amorphous sucrose film, adjusts the preparation process, and optimizes the piezoelectric performance of the sucrose-based piezoelectric coating.

[0007] In order to achieve the above object, the present invention provides a preparation method for a sucrose-based piezoelectric coating, including: Performing a first heat treatment on a sucrose solution to obtain an amorphous sucrose film; Pressing the amorphous sucrose film to promote the vertical growth of crystal seeds to obtain a sucrose-based piezoelectric coating.

[0008] Furthermore, the concentration of the sucrose solution is 0.07 - 0.30 mol / L.

[0009] Furthermore, the first heat treatment is carried out at 80 - 95 °C for 15 - 40 min.

[0010] Furthermore, pressing the amorphous sucrose film to promote the vertical growth of seeds to obtain a sucrose-based piezoelectric coating specifically means that press the amorphous sucrose film under a pressure of 0.2 - 0.5 MPa to make the b-axis of the seeds grow vertically.

[0011] Preferably, spread the sucrose solution on an object with a flat surface to make it spread evenly, so that the amorphous sucrose film is more uniform.

[0012] Preferably, press after the amorphous sucrose film has cooled.

[0013] Furthermore, the thickness of the sucrose solution is 0.5 - 2 mm.

[0014] Furthermore, after obtaining the sucrose-based piezoelectric coating, a second heat treatment is carried out to further promote the growth of seeds.

[0015] Furthermore, the second heat treatment is carried out at 110 - 130 °C for 10 - 30 min.

[0016] The present invention also provides a sucrose-based piezoelectric coating obtained by the above preparation method.

[0017] The present invention also provides the application of the above sucrose-based piezoelectric coating in a piezoelectric sensor.

[0018] The present invention further provides a piezoelectric sensor, which includes a substrate, a sensing layer, and an electrode layer from bottom to top, and the sensing layer includes the above sucrose-based piezoelectric coating.

[0019] It should be noted that in the present invention, the solvent of the sucrose solution does not need to be strictly limited, and it is only necessary to ensure that it can dissolve sucrose within the concentration range. Exemplarily, it can be selected from at least one of water, ethanol, acetone, N,N-dimethylformamide, etc. Considering cost and safety, water is preferably selected. For the first heat treatment of the sucrose solution, preferably, it can be carried out on a preheated flat material, and the preheating temperature is the same as the temperature of the first heat treatment. Pressing the amorphous sucrose film can be achieved by pushing with a smooth plate-like object such as a clean glass sheet or a stainless steel sheet. For the construction of the piezoelectric sensor, the substrate can be selected from a silicon wafer, a silicon carbide wafer, a stainless steel plate, a bolt, etc.; the preparation method of the electrode layer can be to apply silver paste on the sensing layer.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention can successfully prepare a columnar sucrose-based piezoelectric coating without the aid of large-scale film-making equipment. The obtained sucrose-based piezoelectric coating has high crystallization performance and good piezoelectric performance. At the same time, based on the melting point of sucrose itself, the sucrose-based piezoelectric coating and its sensor of the present invention do not need to be prepared at a high temperature, can be formed on the surface of materials with poor temperature tolerance, and realize piezoelectric sensing detection. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 Shows the flowchart of the preparation method of the piezoelectric sensor in Example 1; Figure 2 (a) Shows the force diagram of the amorphous thin film, Figure 2 (b) Shows the schematic diagram of the secondary growth of sucrose crystal seeds to form large crystals, Figure 2 (c) Shows the schematic diagram of the growth direction of the amorphous thin film crystal seeds pushed by the glass plate; Fig. 3(a) and Fig. 3(b) respectively show the cross-sectional view and surface view of the sucrose-based piezoelectric coating prepared in Example 1; Figure 4 Shows the XRD characterization diagram of the sucrose-based piezoelectric coatings prepared in Example 1 and Example 2; Figure 5 Shows the ultrasonic signal diagram of the piezoelectric sensor prepared in Example 1; Figure 6 Shows the piezoelectric constant d of the piezoelectric sensors prepared in Example 1, Examples 3-4, and Comparative Examples 1-5 33 Test results; Figure 7 Shows the ultrasonic signal test and piezoelectric constant d of the sensors prepared in Example 1, Examples 5-8, and Comparative Examples 6-9 33 Test results; Figure 8 Shows the piezoelectric constant d of the sensors prepared in Example 1 and Comparative Examples 10-11 33 Test results. Detailed Embodiments

[0023] In the ranges disclosed in the present invention, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the specific embodiments of the present invention and the accompanying drawings of the specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0025] Embodiment 1 As Figure 1 shown, a preparation method of a piezoelectric sensor includes the following steps: (1) Preheat the substrate: Select a clean stainless steel plate as the substrate, place it on a heating table, and in the air, set the heating temperature of the heating table to 90 °C and keep it for 20 min to preheat the substrate. (2) Form a liquid layer: Drop a 0.18 mol / L sucrose aqueous solution on the preheated substrate to form a liquid layer about 1.5 mm thick. (3) Form an amorphous sucrose film: Perform the first heat treatment, turn on the heating table and continue heating at 90 °C for 30 min to dry the liquid layer to form an amorphous sucrose film. (4) Form an amorphous thin film: Turn off the heating table and let the amorphous sucrose film stand and cool to room temperature to obtain an amorphous thin film. (5) Promote crystal growth for the first time: Under a pressure of 0.3 MPa, push the amorphous thin film through a glass plate to form seeds with the b-axis perpendicular to the surface of the substrate, and obtain a small columnar crystal piezoelectric layer. (6) Promote crystal growth for the second time: Perform the second heat treatment, turn on the heating table and heat the substrate and the crystallization layer at 120 °C for 30 min to promote crystal growth for the second time. (7) Form a piezoelectric layer: Turn off the heating table and cool to room temperature to form a sucrose-based piezoelectric coating. (8) Form a sensor: Prepare an electrode layer with a thickness of 0.2 mm on the surface of the sucrose-based piezoelectric coating in the form of silver paste dot coating.

[0026] In this embodiment, the formation principle of the seeds with the b-axis perpendicular to the surface of the substrate is as Figure 2When the glass plate pushes and presses the amorphous thin film, there is a very high pressure at the point where the glass plate contacts the amorphous thin film. Since the amorphous sucrose layer is metastable and the crystalline state is stable, the amorphous sucrose near these contact points easily transforms from the metastable state to the stable state, that is, small sucrose crystal seeds with the b-axis perpendicular to the substrate surface begin to form, as shown in Figure 2 Figs. (a)-(c); When the second heat treatment is carried out, the heating environment promotes the secondary growth of sucrose crystal seeds to form mature large crystals, as shown in Figure 2 Fig. (b).

[0027] Example 2 A preparation method of a piezoelectric sensor includes the following steps: (1) Preheating the substrate: Select a clean stainless steel plate as the substrate and place it on a heating table. In air, set the heating temperature of the heating table to 90 °C and keep it for 20 min to preheat the substrate; (2) Forming a liquid layer: Drop a 0.18 mol / L sucrose aqueous solution on the preheated substrate to form a liquid layer about 1.5 mm thick; (3) Forming an amorphous sucrose film: Carry out the first heat treatment, turn on the heating table and continue heating at 90 °C for 30 min to dry the liquid layer to form an amorphous sucrose film; (4) Forming an amorphous thin film: Turn off the heating table and let the amorphous sucrose film stand and cool to room temperature to obtain an amorphous thin film; (5) Promoting crystal growth for the first time: Under a pressure of 0.3 MPa, push the amorphous thin film through a glass plate to form crystal seeds with the b-axis perpendicular to the substrate surface, forming a sucrose-based piezoelectric coating; (6) Forming a sensor: Prepare an electrode layer with a thickness of 0.2 mm on the surface of the sucrose-based piezoelectric coating in the form of silver paste dot coating.

[0028] The morphology of the sucrose-based piezoelectric coating prepared in Example 1 was observed by scanning electron microscopy. It can be seen that a sucrose-based piezoelectric coating with a thickness of about 17 μm was formed. Since sucrose is an organic substance with extremely poor conductivity, obvious columnar crystal morphology was still observed in the cross-section of the coating, and the crystal grains grew along the b-axis, as shown in Fig. 3(a). It can be seen from Fig. 3(b) that the surface of the sucrose-based piezoelectric coating prepared in Example 1 is relatively regular, similar to a structure stacked by nanosheets.

[0029] The crystal structures of the sucrose-based piezoelectric coatings prepared in Example 1 and Example 2 were observed by X-ray diffraction. It can be seen from Figure 4 that the sucrose-based piezoelectric coatings prepared in Example 1 and Example 2 both have (002) orientation. At the same time, compared with Example 2, the (002) peak of Example 1 that has undergone the secondary promotion of crystal growth step is higher, indicating that the formed columnar crystals have higher quality and larger size.

[0030] The ultrasonic signals of the piezoelectric sensors constructed in Example 1 were also tested. As Figure 5 shown, it has an ultrasonic signal of 0.35 V and a piezoelectric constant d 33 of 3.5 pC / N.

[0031] Examples 3 - 4 Compared with Example 1, the difference is that in the secondary promotion of crystal growth in step (6), the heating times of the second heat treatment are 10 and 20 min, respectively.

[0032] Comparative Examples 1 - 5 Compared with Example 1, the difference is that in the secondary promotion of crystal growth in step (6), the heating times of the second heat treatment are 1, 5, 35, 40, and 50 min.

[0033] Piezoelectric constant d tests were carried out on the piezoelectric sensors prepared in Example 1, Examples 3 - 4, and Comparative Examples 1 - 5. 33 The results are as Figure 6 shown. It can be seen that when the heating duration used for the secondary promotion of crystal growth is less than 10 min, the crystal growth of the crystallization layer is not fully promoted, resulting in very weak piezoelectric properties of the sucrose-based piezoelectric coating. When the heating duration used for the secondary promotion of crystal growth is more than 30 min, the crystals in the crystallization layer have been fully formed, and further increasing the heating duration will not improve the piezoelectric properties. Therefore, considering the sensor performance and manufacturing cost comprehensively, the heating duration (i.e., the second heat treatment duration) used for the secondary promotion of crystal growth should be between 10 - 30 min.

[0034] Examples 5 - 8 Compared with Example 1, the difference is that in the formation of the liquid layer in step (2), the concentrations of the sucrose aqueous solution are 0.07, 0.12, 0.25, and 0.30 mol / L, respectively.

[0035] Comparative Examples 6 - 9 Compared with Example 1, the difference is that in the formation of the liquid layer in step (2), the concentrations of the sucrose aqueous solution are 0.02, 0.05, 0.32, and 0.35 mol / L, respectively.

[0036] Ultrasonic signal tests and piezoelectric constant d tests were carried out on the sensors prepared in Example 1, Examples 5 - 8, and Comparative Examples 6 - 9. 33 The results are as Figure 7 shown. It can be seen that when the concentration of the sucrose aqueous solution is less than 0.07 mol / L, both the ultrasonic signal and the piezoelectric constant d of the sensor 33 decrease sharply; at the same time, when the concentration of the sucrose aqueous solution is higher than 0.30 mol / L, both the ultrasonic signal and the piezoelectric constant d of the sensor 33It also drops sharply, that is, the concentration of the sucrose aqueous solution should be between 0.07 - 0.30 mol / L.

[0037] Comparative Example 10 Compared with Example 1, the difference lies in that: in the formation of the liquid layer in step (5), seeds with the a-axis perpendicular to the substrate surface are formed to form a sucrose-based piezoelectric coating.

[0038] Comparative Example 11 Compared with Example 1, the difference lies in that: in the formation of the liquid layer in step (5), seeds with the c-axis perpendicular to the substrate surface are formed to form a sucrose-based piezoelectric coating.

[0039] Piezoelectric constant d of the sensors prepared in Example 1 and Comparative Examples 10 - 11 was 33 tested, and the results are as Figure 8 , it can be seen that the seeds grown along the a- and c-axes will both weaken the piezoelectric constant.

[0040] In summary, the present invention can successfully prepare a columnar sucrose-based piezoelectric coating without relying on large-scale film-forming equipment. The obtained sucrose-based piezoelectric coating has high crystallization performance and good piezoelectric performance. At the same time, based on the melting point of sucrose itself, the sucrose-based piezoelectric coating of the present invention does not need to be prepared at a high temperature and can achieve piezoelectric sensing detection on the surface of materials with poor temperature tolerance.

[0041] Finally, it should be noted that: the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a sucrose-based piezoelectric coating, characterized in that: include, subjecting the sucrose solution to a first heat treatment to obtain an amorphous sucrose film; The amorphous sucrose film is pressed to promote the vertical growth of seed crystals to obtain a sucrose-based piezoelectric coating.

2. The method for preparing a sucrose-based piezoelectric coating according to claim 1, characterized in that: The concentration of the sucrose solution is 0.07-0.30 mol / L.

3. The method for preparing a sucrose-based piezoelectric coating according to claim 1, characterized in that: The first heat treatment is carried out at 80-95° C. for 15-40 min.

4. The method for preparing a sucrose-based piezoelectric coating according to claim 1, characterized in that: The pressing of the amorphous sucrose film to promote the vertical growth of the seed crystals to obtain the sucrose-based piezoelectric coating is specifically as follows: The amorphous sucrose film was pressed at a pressure of 0.2-0.5 MPa to allow the b-axis of the seed crystal to grow vertically.

5. The method for preparing a sucrose-based piezoelectric coating according to claim 1, characterized in that: The thickness of the sucrose solution is 0.5-2 mm.

6. The method for preparing a sucrose-based piezoelectric coating according to any one of claims 1 to 5, characterized in that: After obtaining the sucrose-based piezoelectric coating, a second heat treatment is performed to promote seed growth again.

7. The method for preparing a sucrose-based piezoelectric coating according to claim 6, characterized in that: The second heat treatment is performed at 110-130° C. for 10-30 min.

8. A sucrose-based piezoelectric coating, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the sucrose-based piezoelectric coating according to claim 8 in a piezoelectric sensor.

10. A piezoelectric sensor, comprising, from bottom to top, a substrate, a sensing layer and an electrode layer, characterized in that: The sensing layer comprises the sucrose-based piezoelectric coating of claim 8.

Images