High-sensitivity vibration-electrochemical transducer and preparation method thereof

Abstract

The invention belongs to the field of electrochemical transducers, and particularly relates to a high-sensitivity vibration-electrochemical transducer and a preparation method thereof.The high-sensitivity vibration-electrochemical transducer comprises four layers of porous electrodes which are arranged according to an anode-cathode-cathode-anode mode, the porous electrodes are isolated through insulating films, and the insulating films are arranged between the porous electrodes; wherein a middle layer, a seed layer, a nano cilia array on the surface of the seed layer and a platinum nano film on the surface of the nano cilia array are sequentially arranged on the inner wall of a hole of each layer of porous electrode from inside to outside. According to the invention, the size of the transducer can be reduced while the sensitivity of the vibration-electrochemical transducer is greatly improved, so that the transducer is convenient to integrate.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical transducers, and in particular relates to a high-sensitivity vibration-electrochemical transducer and a preparation method thereof. Background Art

[0002] In recent years, due to the rapid development of smart devices, environmental monitoring, health diagnosis and other fields, the demand for multifunctional, highly sensitive, low-power and miniaturized sensors has been growing, and the research on transducer units used in new sensors has received widespread attention. The vibration-electrochemical transducer combines the high sensitivity of electrochemical sensors with the dynamic detection capability of inertial sensors, and is one of the important directions for the next generation of new vibration sensors. At present, it has a large number of applications in hydrophones, geophones, and seismometers, such as the MTSS seismometer developed and produced by the Russian R sensors company, and the CME series of long-period seismometer products for long-period natural earthquake monitoring.

[0003] The vibration-electrochemical transducer is mainly composed of 4 porous electrodes, which are arranged in a certain direction in the form of anode-cathode-cathode-anode, and each electrode is isolated by an insulating film. When working, it is generally placed in a cavity filled with electrolyte, and the external circuit applies voltage to the two anode electrodes, and the cathode is used as the measuring electrode output. The principle of detecting vibration is as follows: when the cavity vibrates relative to the transducer electrode in a direction perpendicular to the transducer electrode, the liquid will flow between the electrodes, and the ions near the electrodes will produce a concentration difference, causing the cathode to output a current proportional to the liquid flow rate, thereby completing the detection of vibration.

[0004] The vibration-electrochemical transducer has the advantages of good low-frequency performance, high sensitivity, and easy integration. In addition, the vibration-electrochemical transducer using fluid as the working medium can also reduce noise, expand the passband bandwidth, and improve the signal-to-noise ratio.

[0005] In order to improve the sensitivity of the vibration-electrochemical transducer, the existing methods include increasing the surface area of ​​the electrode, reducing the electrode opening and increasing the electrode opening rate. Increasing the electrode surface area generally adopts the method of increasing the size of the electrode. Although it improves the sensitivity of the vibration-electrochemical transducer, it increases the cost of the vibration-electrochemical transducer and makes it difficult to integrate the vibration-electrochemical transducer into a relatively small instrument. Although reducing the electrode opening will not change the size of the electrode, the smaller electrode opening will affect the flow rate of the liquid on the electrode surface, thereby affecting the sensitivity of the vibration-electrochemical transducer. Increasing the electrode opening rate is difficult in terms of technology, greatly increases the production cost and is very likely to cause damage to the electrode, reducing the preparation rate of the vibration-electrochemical transducer. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a highly sensitive vibration-electrochemical transducer and a preparation method, which can greatly improve the sensitivity while reducing the size of the vibration-electrochemical transducer, so that the transducer is easy to integrate; and the preparation method has a simple process, a high preparation rate, is easy to mass produce, and saves costs.

[0007] The present invention is achieved in this way.

[0008] A highly sensitive vibration-electrochemical transducer comprises four layers of porous electrodes arranged in an anode-cathode-cathode-anode pattern, wherein the porous electrodes are isolated by insulating films, wherein the inner wall of the holes of each layer of the porous electrodes comprises, from the inside to the outside, an intermediate layer, a seed layer, a nanociliar array on the surface of the seed layer, and a platinum nanofilm on the surface of the nanociliar array.

[0009] Furthermore, the intermediate layer is made of titanium thin film.

[0010] Furthermore, the seed layer and the nanociliary array are made of zinc oxide.

[0011] A method for preparing a highly sensitive vibration-electrochemical transducer, comprising:

[0012] A protective film is evenly attached to the upper and lower surfaces of the electrode plate, and a plurality of evenly distributed circular or square hole arrays are punched on the electrode plate with a laser. The magnetron sputtering technology is used on the side wall of the hole to first deposit a 2-3nm thick titanium layer as an intermediate layer, and then deposit a 18-25nm thick zinc oxide layer as a seed layer. After the deposition is completed, the protective film is removed;

[0013] The electrode plate with the seed layer is immersed in a pre-configured reaction solution, and the working temperature is maintained at 70°C-90°C. The ions in the reaction solution use the seed layer as the micro-growth starting point and gradually form a nanofibril array on the seed layer.

[0014] Atomic layer deposition technology is used to uniformly deposit platinum nanofilms on the surface of the nanociliary array to produce the optimal platinum film thickness;

[0015] A 10-20 μm thick insulating layer is deposited on the upper and lower surfaces of the electrode sheet using a magnetron sputtering process;

[0016] The side wall of the channel is coated with UV photoresist to completely wrap the nanociliary array in the photoresist;

[0017] During assembly, the electrode sheets are loaded into the mold one by one, and each layer of electrode sheets is connected with an ultra-thin bonding adhesive with a thickness of 2-5 μm;

[0018] After assembly, UV photoresist is removed by ultraviolet exposure and developer immersion.

[0019] Furthermore, the protective film is a UV film or a hot-melt film.

[0020] Furthermore, the insulating layer is made of silicon dioxide, aluminum oxide or hafnium oxide.

[0021] Furthermore, the optimal platinum film thickness is 5nm-8nm.

[0022] Furthermore, the pre-configured reaction solution consists of 15 mM hexamethylenetetramine and 20 mM zinc nitrate solution.

[0023] Compared with the prior art, the present invention has the following beneficial effects: Starting from the microstructure of the electrode array, the present invention uses micro-nano processing technology to construct a nanoscale ciliary array structure on the electrode surface of the transducer. This ciliary array structure can greatly increase the specific surface area of ​​the electrode (the surface area per unit mass of material), provide more active sites for electrochemical reactions, promote the electrochemical reactions, and greatly improve the sensitivity of the electrochemical transducer. Without sacrificing the electromechanical conversion efficiency of the vibration-electrochemical transducer, the present invention greatly reduces the size of the vibration-electrochemical transducer, is easy to integrate, has a high preparation rate of the electrochemical transducer, has low material loss, can save costs, has a simple process, and is easy to mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of a highly sensitive vibration-electrochemical transducer and a preparation method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] The vibration-electrochemical transducer involved in the present invention is mainly composed of 4 porous electrodes, which are arranged in an anode-cathode-cathode-anode manner along a certain direction, and the porous electrodes are isolated by an insulating film. The vibration-electrochemical transducer is placed in a cavity filled with electrolyte, and an external circuit applies voltage to the two anode electrodes, and the cathode serves as a measuring electrode output. The present invention starts with the microstructure of the electrode array and uses micro-nano processing technology to construct a nanoscale ciliary array structure on the surface of the transducer electrode. This ciliary array structure can greatly increase the specific surface area of ​​the electrode (the surface area per unit mass of material), provide more active sites for the electrochemical reaction, thereby promoting the electrochemical reaction and greatly improving the sensitivity of the vibration-electrochemical transducer.

[0027] In the present invention, the inner wall of the hole of each layer of porous electrode has an intermediate layer, a seed layer, a nanofibril array on the surface of the seed layer, and a platinum nanofilm on the surface of the nanofibril array in order from the inside to the outside. The intermediate layer is made of titanium film. The seed layer and the nanofibrils are made of zinc oxide.

[0028] See also Figure 1 As shown, the present invention provides a method for manufacturing a highly sensitive vibration-electrochemical transducer, comprising:

[0029] First, a protective film is evenly attached to the upper and lower surfaces of the electrode plate, and some evenly distributed circular or square hole arrays are punched on the electrode plate with a laser. An intermediate layer is deposited on the side walls of the holes, and a seed layer of the same material as the nanofibril material is deposited. After the deposition is completed, the protective film is torn off.

[0030] Then the electrode sheet with the seed layer deposited on the side wall of the channel is immersed in the pre-configured reaction solution and the working temperature is maintained at 70℃-90℃. The ions in the reaction solution start from the micro-growth of the seed layer and gradually form a nanociliary array on the seed layer.

[0031] After the growth of the nanociliary array is completed, the atomic layer deposition technology (ALD) is used to evenly deposit a platinum nanofilm on the surface of the nanociliary array. The optimal platinum film thickness is produced by adjusting parameters such as pulse time, waiting time, reaction chamber temperature and sintering temperature.

[0032] Finally, the magnetron sputtering process is used to deposit an insulating layer on the upper and lower sides of the electrode sheet, and finally a high-precision mold is used for assembly. Before assembly, the side wall of the channel is treated with UV photoresist wrapping, and the nanofibril array is completely wrapped in the photoresist. During assembly, the electrode sheets are sequentially loaded into the mold, and each layer of the electrode sheets is connected with an ultra-thin bonding glue with uniform thickness. After the assembly is completed, ultraviolet exposure and developer immersion are used to remove the UV photoresist to complete the preparation of the present invention.

[0033] The present invention starts with the microstructure of the electrode array and uses micro-nano processing technology to construct a nanoscale ciliary array structure on the electrode surface of the vibration-electrochemical transducer. This ciliary array structure can greatly increase the specific surface area of ​​the electrode (the surface area per unit mass of material), provide more active sites for the electrochemical reaction, promote the electrochemical reaction, and greatly improve the sensitivity of the electrochemical transducer.

[0034] Since platinum has good chemical stability, low self-resistance, and is not easy to polarize, it is one of the most commonly used inert electrodes in the electrochemical transducer system. Therefore, the electrode material mainly used in the preparation of the vibration-electrochemical transducer by this method is platinum.

[0035] The electrochemical reaction of the vibration-electrochemical transducer occurs on the side walls of the electrode sheet pores. In order to promote the electrochemical reaction on the electrode surface, a nanofibrillar structure array with a large specific surface area is constructed on the side walls of the electrode sheet pores.

[0036] The specific process includes:

[0037] First, laser drilling is performed on the electrode plate made of platinum, and a seed layer of the same material as the nanociliary array is deposited on the side wall of the hole using a magnetron sputtering process to facilitate the subsequent construction of the nanociliary array. In order to protect the upper and lower surfaces of the electrode plate, a layer of protective film is evenly attached to the upper and lower surfaces of the electrode plate before laser drilling. The protective film is a UV film or hot-melt film with good adhesion and easy to remove later. To ensure the adhesion of the seed layer of the ciliary material to the surface of the electrode plate, it is necessary to deposit an intermediate layer in advance, and then deposit a seed layer of the same material as the ciliary material. Since the upper and lower surfaces are attached with protective films, the material seeds will only be deposited on the side walls previously formed by laser drilling. After the deposition is completed, the protective films on the upper and lower surfaces are torn off.

[0038] The middle layer is made of titanium thin film, which is prepared by magnetron sputtering process.

[0039] The magnetron sputtering deposition method used in the embodiment of the present invention is to generate incident ions by low-pressure inert gas glow discharge. The cathode target is made of a coating material, the substrate is used as an anode, 0.1-10Pa of argon or other inert gas is introduced into the vacuum chamber, and a glow discharge is generated under the action of a cathode 1-3kV DC negative high voltage or a 13.56MHz radio frequency voltage. The ionized argon ions bombard the target surface, causing the target atoms to sputter and deposit on the substrate to form a thin film.

[0040] The seed layer of growing cilia makes them become cilia. In the selection of cilia materials, zinc oxide has stable chemical properties, strong resistance to temperature and chemical corrosion, non-toxicity, and compared with some other nanomaterials (such as silver, gold, etc.), it has less impact on the environment and has good biocompatibility; and the nanociliary array made of zinc oxide material can be grown by a mild chemical solution method, and can achieve selective regional growth by selectively depositing a seed layer. Therefore, the material used for the nanociliary array in the present invention is zinc oxide. The following is a method for growing a zinc oxide nanociliary array.

[0041] The platinum electrode sheet with a zinc oxide seed layer deposited on the side wall of the channel is immersed in a pre-configured reaction solution, which consists of 15mM hexamethylenetetramine and 20mM zinc nitrate solution.

[0042] The reaction solution usually contains a certain concentration of zinc nitrate as a source of zinc, urotropine as a reducing agent, and ammonia water to adjust the pH value of the solution. The working temperature is maintained at 70-90°C, and the zinc ions in the reaction solution use the zinc oxide seed layer as the starting point for micro-growth, and gradually form a nanociliary array on the seed layer. By controlling the ion concentration of the solution, the density of the nanociliary array can be effectively controlled. By controlling the reaction time of the solution, the length of the nanociliary can be precisely controlled. The morphology, density, length and other parameters of the nanociliary array will be characterized by scanning electron microscopy.

[0043] After the zinc oxide nanofibril array is grown, in order to maintain or even improve the performance of the electrode, the present invention uses atomic layer deposition (ALD) technology to uniformly deposit platinum nanofilms on the surface of the zinc oxide nanofibril array. Because ALD can achieve uniform deposition of films with precisely controllable thickness on complex three-dimensional structures through self-limiting surface chemical reactions. The optimal platinum film thickness is 5nm-8nm.

[0044] Finally, interlayer insulation and electrode alignment assembly are carried out.

[0045] In order to further optimize the performance of the vibration-electrochemical transducer, a magnetron sputtering process is used to deposit an insulating layer on the upper and lower sides of the electrode sheet to form a porous insulating layer. Without sacrificing the stability of the electrode, the electrode spacing is further reduced, thereby improving the sensitivity of the electrochemical transducer. In the selection of insulating materials, the present invention uses three materials: silicon dioxide, aluminum oxide and hafnium oxide. These materials have good insulation and chemical stability, and can meet the requirements of the electrochemical transducer for the insulating layer. A 10-20μm thick insulating layer is deposited on the upper and lower surfaces of the electrode sheet using a magnetron sputtering process.

[0046] In order to achieve high-precision and high-efficiency assembly, the present invention adopts a set of high-precision molds. The mold is accurately modeled on demand by CAD (to ensure perfect assembly). At the same time, the mold material is selected from high-strength and high-wear-resistant special alloy materials (to ensure dimensional stability and service life). Before assembly, the side walls of the channel are wrapped with UV photoresist to completely wrap the nanofibril array in the photoresist to prevent the bonding glue from damaging the nanofibril array. During assembly, the electrode sheets are loaded into the mold in sequence, and each layer of electrode sheets is connected with an ultra-thin bonding glue with uniform thickness, and each layer of electrode sheets is connected with an ultra-thin bonding glue with a thickness of about 2-5μm. After assembly is completed, UV exposure and developer soaking are used to remove the UV photoresist. Through ultraviolet exposure, the photoresist undergoes a photochemical reaction, the structure changes, and it becomes extremely soluble. Then the electrode is immersed in the developer, and the photoresist gradually dissolves in the developer and is finally completely removed. In this way, a complete electrochemical transducer is prepared.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A highly sensitive vibration-electrochemical transducer, characterized in that: It includes four layers of porous electrodes arranged in an anode-cathode-cathode-anode pattern, and the porous electrodes are isolated by insulating films. The inner wall of the pores of each layer of porous electrode has, from the inside to the outside, an intermediate layer, a seed layer, a nanociliar array on the surface of the seed layer, and a platinum nanofilm on the surface of the nanociliary array.

2. The highly sensitive vibration-electrochemical transducer according to claim 1, characterized in that: The intermediate layer is made of titanium thin film.

3. The highly sensitive vibration-electrochemical transducer according to claim 1, characterized in that: The seed layer and the nanociliary array are made of zinc oxide.

4. A method for preparing a highly sensitive vibration-electrochemical transducer, characterized in that: include: A protective film is evenly attached to the upper and lower surfaces of the electrode plate, and a plurality of evenly distributed circular or square hole arrays are punched on the electrode plate with a laser. The magnetron sputtering technology is used on the side wall of the hole to first deposit a 2-3nm thick titanium layer as an intermediate layer, and then deposit a 18-25nm thick zinc oxide layer as a seed layer. After the deposition is completed, the protective film is removed; The electrode plate with the seed layer is immersed in a pre-configured reaction solution, and the working temperature is maintained at 70°C-90°C. The ions in the reaction solution use the seed layer as the micro-growth starting point and gradually form a nanofibril array on the seed layer. Atomic layer deposition technology is used to uniformly deposit platinum nanofilms on the surface of the nanociliary array to produce the optimal platinum film thickness; A 10-20 μm thick insulating layer is deposited on the upper and lower surfaces of the electrode sheet using a magnetron sputtering process; The side wall of the channel is coated with UV photoresist to completely wrap the nanociliary array in the photoresist; During assembly, the electrode sheets are loaded into the mold one by one, and each layer of electrode sheets is connected with an ultra-thin bonding adhesive with a thickness of 2-5 μm; After assembly, UV photoresist is removed by ultraviolet exposure and developer immersion.

5. The method for preparing a highly sensitive vibration-electrochemical transducer according to claim 4, characterized in that: The protective film is a UV film or a hot-melt film.

6. The method for preparing a highly sensitive vibration-electrochemical transducer according to claim 4, characterized in that: The insulating layer is made of silicon dioxide, aluminum oxide or hafnium oxide.

7. The method for preparing a highly sensitive vibration-electrochemical transducer according to claim 4, characterized in that: The optimal platinum film thickness is 5nm-8nm.

8. The method for preparing a highly sensitive vibration-electrochemical transducer according to claim 4, characterized in that: The pre-prepared reaction solution consists of 15 mM hexamethylenetetramine and 20 mM zinc nitrate solution.

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