Liquid metal ultrasonic energy collection system and preparation method thereof

Abstract

The invention belongs to the technical field of energy collection, and particularly relates to a liquid metal ultrasonic energy collection system and a preparation method thereof.The energy collection system comprises a substrate, liquid metal, a friction layer and a working electrode; the liquid metal is arranged on the substrate, the friction layer is an oxide layer on the surface of the liquid metal, and the working electrode is inserted into the liquid metal through the oxide layer; during application, one end of a load is connected with the working electrode, and the other end of the load is grounded. The energy conversion path is novel and efficient, and is different from a traditional friction nano-generator depending on entity contact, a non-contact and interface-driven energy collection mechanism is constructed through liquid metal surface oxidation-reduction reaction and ultrasonic stress coupling, energy conversion is more efficient, and loss is lower. In addition, the system outputs a high-voltage direct-current electric signal, a rectifier bridge, a power management chip or an external regulation and control circuit is not needed, the system structure is simplified, energy loss is reduced, and the overall energy efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of energy collection, and in particular relates to a liquid metal ultrasonic energy collection system and a preparation method thereof. Background Art

[0002] Among many environmental energy sources, ultrasonic energy has good adaptability and safety in confined spaces, biological tissues or complex structures, and has become one of the most promising energy forms in microscale scenarios because of its strong directionality, high propagation efficiency and strong penetration ability. For example, in implantable medical devices, ultrasound can penetrate tissues without loss for deep energy transmission; in sensor nodes in closed environments, ultrasound provides a non-contact, remotely coupled energy collection method.

[0003] In order to achieve energy harvesting from ultrasound or low-frequency vibrations, existing technologies mostly use structures such as friction nanogenerators or piezoelectric generators, relying on mechanical movement to form charge separation between solid interfaces. Among them, the friction layer, as the core structure of energy conversion, usually uses polymers (such as PTFE, PDMS) or dielectric materials, which are repeatedly in contact and rubbed with the surface of the conductor to form an electrified layer. However, the traditional friction layer is a solid material and lacks flexibility. It is difficult to adapt to miniaturized, deformable or complex curved surface environments; in addition, due to its reliance on physical contact friction, it is easy to produce material fatigue and loss, and it is difficult to work stably for a long time.

[0004] In addition, the direct contact of physical mechanical energy conversion not only increases the complexity of the system and the loss of the device, but also introduces additional energy loss due to the need for rectifier bridge management of AC output, limiting the potential of nanogenerators in miniaturization and practical applications. In complex scenarios, with the demand for smaller size and higher energy efficiency devices, the stable integration of non-contact, high-voltage DC fast charging and environmental sensing energy collection and self-power supply is particularly urgent. Summary of the invention

[0005] To solve the above problems, the present invention provides, on the one hand, a liquid metal ultrasonic energy collection system, comprising a substrate, liquid metal, a friction layer, and a working electrode; the liquid metal is placed on the substrate, the friction layer is an oxide layer on the surface of the liquid metal, and the working electrode is inserted into the liquid metal through the oxide layer; when used, one end of the load is connected to the working electrode, and the other end of the load is grounded.

[0006] The liquid metal ultrasonic energy collection system of the present invention is based on the interfacial charge separation and potential difference response generated by the liquid metal surface oxide layer under ultrasonic drive. When the ultrasonic wave acts on the system, periodic mechanical stress and micro-displacement will be generated between the liquid metal and the substrate, resulting in dynamic changes such as wrinkling, fracture and reorganization of the oxide layer on the surface of the liquid metal. These changes induce contact electrification effect and electrostatic induction effect between the liquid metal and the medium interface. At the same time, since the liquid metal has excellent fluidity, it can promote the redistribution of charges and enhance the potential difference through the Marangoni effect. When the working electrode is connected to the load, the potential difference drives the electrons to flow along the circuit direction, outputting a stable DC signal, thereby realizing efficient conversion of ultrasonic energy into electrical energy.

[0007] Furthermore, the substrate is silicon dioxide. Silicon dioxide has excellent mechanical strength and chemical stability, ensuring that the liquid metal flows stably on its surface, is not prone to reaction or damage, and provides a reliable support structure. At the same time, silicon dioxide, as an electrical insulator, can effectively prevent current leakage and ensure efficient conduction and collection of electrical energy.

[0008] Furthermore, the thickness of the substrate is 2 mm to 3 mm.

[0009] Furthermore, the liquid metal is a gallium-indium-tin alloy, or one of the binary combinations of indium, gallium, and tin, or a combination of the three elements of indium, gallium, and tin. The flow effect of the gallium-indium-tin alloy under ultrasonic drive promotes charge redistribution through the Marangoni mechanism, breaks the original charge balance state, and allows the charge to migrate to the working electrode or substrate interface more quickly, thereby enhancing the speed and intensity of establishing the potential difference and improving the energy collection efficiency. Especially in a dynamic ultrasonic environment, the Marangoni drive provides a continuous, non-contact charge transport method, which not only improves the stability and consistency of the output electrical signal, but also enhances the system's response to low-frequency, micro-amplitude mechanical disturbances, which helps to achieve a more sensitive and adaptable energy conversion process.

[0010] Furthermore, the material of the working electrode is copper.

[0011] Furthermore, the diameter of the working electrode is 0.06 mm to 0.10 mm.

[0012] Furthermore, the thickness of the oxide layer is 0.007mm to 0.03mm. When the stress changes and the oxide layer breaks to expose the liquid metal core itself, the liquid metal therein reacts with the oxygen in the environment to undergo a redox reaction. The wrinkle morphology of the oxide layer changes with the stress changes during the growth of the oxide layer, and a one-dimensional stripe or a two-dimensional maze pattern is formed on the surface of the liquid metal. The large-radius wrinkles induced by ultrasonic stress coexist with nanoscale wrinkles, further enhancing the dynamic characteristics of the interface. In addition, the presence of the oxide layer helps to stabilize the interface charge and improve the efficiency of contact electrification. At the same time, the micro-displacement generated under ultrasonic excitation leads to relative movement between the liquid metal and the substrate, further enhancing the electrostatic induction effect and forming a considerable potential difference in the circuit. With the continued action of periodic mechanical stress, the charge in the system is continuously redistributed, thereby achieving a stable DC signal output.

[0013] There are two interfaces in the present invention: one is the interface between the oxide layer and the liquid metal, and the other is the interface between the liquid metal and the substrate. For the interface between the oxide layer and the liquid metal, the oxide layer naturally formed on the surface of the liquid metal has certain mechanical strength and electrical insulation. Driven by ultrasound, the oxide layer will undergo dynamic changes such as wrinkling, breaking and reorganization, prompting the separation of charges at the interface between the liquid metal and the oxide layer. The interface converts ultrasonic energy into electrical energy through contact electrification effect and electrostatic induction effect, thereby achieving effective energy collection. For the interface between the liquid metal and the substrate, the interface between the liquid metal and the silicon dioxide substrate plays a supporting role and provides a stable physical support structure. Due to the chemical stability and mechanical strength of silicon dioxide, the liquid metal can flow stably on its surface, and silicon dioxide, as an electrical insulator, prevents current leakage and ensures the effective collection of electrical energy. The synergistic effect of these two interfaces greatly improves the overall energy collection efficiency of the system by optimizing the separation and transmission mechanism of charges. At the interface between the oxide layer and the liquid metal, the dynamic action of ultrasound promotes charge separation, while the interface between the liquid metal and the substrate ensures the stability of the system and the effectiveness of the current conduction path. The combination of the two enables the liquid metal ultrasonic energy harvesting system to efficiently convert ultrasonic energy into electrical energy with high stability and durability.

[0014] On the other hand, the present invention provides a method for preparing a liquid metal ultrasonic energy collection system, comprising the following steps: Step 1, using plasma to clean the substrate; Step 2, carrying liquid metal on the substrate; Step 3: Insert the working electrode into the liquid metal.

[0015] Furthermore, step 2 also includes setting micron-scale grooves or patterns on the substrate. Micron-scale grooves can also effectively control the diffusion of liquid metal and ensure that it remains stable on the substrate surface. The local stable areas formed by liquid metal in these grooves avoid the disordered expansion of liquid metal, which helps to maintain the structural integrity of the system and long-term efficient energy collection. The grooves can also produce local reflection and refraction effects on the propagation of ultrasound, concentrating the ultrasonic energy in specific areas. In this way, the micron-scale grooves can not only enhance the interface interaction between the liquid metal and the oxide layer, but also produce stronger local stress and micro-displacement on the surface of the liquid metal, which helps to promote the separation of charges and the increase of potential difference. More importantly, the presence of micron-scale grooves allows the liquid metal to form more contact points on the substrate surface, which can produce stronger dynamic changes under the drive of ultrasound, further promoting the occurrence of contact electrification effect and electrostatic induction effect.

[0016] Furthermore, step 3 also includes removing the oxide layer on the surface of the working electrode.

[0017] Beneficial effects of the present invention: (1) The energy conversion path of the present invention is novel and efficient. Unlike the traditional friction nanogenerator that relies on physical contact, the present invention couples the redox reaction on the liquid metal surface with ultrasonic stress to construct a non-contact, interface-driven energy collection mechanism, which has more efficient energy conversion and lower loss.

[0018] (2) The output of the present invention is a high-voltage direct current signal, and the electric energy generated is stable high-voltage direct current. No rectifier bridge, power management chip or external control circuit is required, which simplifies the system structure, reduces energy loss and improves overall energy efficiency.

[0019] (3) The present invention has liquid flexibility and self-healing ability. Liquid metal has excellent fluidity, flexibility and regenerative properties of the oxide layer. It can adapt to a variety of deformation environments and restore its function after micro-damage to achieve long-term stable operation.

[0020] (4) The present invention has a simple structure and eliminates the need for a traditional rigid friction layer or piezoelectric unit. Energy harvesting is achieved through non-contact coupling via ultrasonic excitation, which makes the present invention particularly suitable for stable operation and energy output in miniaturized, deformable or complex curved environments.

[0021] Based on the above beneficial effects, the present invention has good application prospects in the field of energy collection technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a liquid metal ultrasonic energy harvesting system.

[0023] Figure 2Schematic diagram of testing the liquid metal ultrasonic energy harvesting system.

[0024] Figure 3 (ac) are electrical signals when the substrate materials are silicon dioxide, copper, and gallium oxide, respectively: (a) silicon dioxide, (b) copper, and (c) gallium oxide; (d) the charge signal of the liquid metal ultrasonic energy harvesting system when the substrate is silicon dioxide.

[0025] Figure 4 The voltage signal and circuit signal of the liquid metal ultrasonic energy collection system collecting horizontal and vertical ultrasonic waves: (a) voltage signal, (b) current signal.

[0026] Figure 5 Schematic diagram of the change in contact angle of the liquid metal ultrasonic energy harvesting system before and after ultrasonic treatment: i) has never been treated with ultrasound, ii) has been treated with ultrasound for 10 hours.

[0027] In the figure: 1. substrate; 2. liquid metal; 3. working electrode. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples.

[0029] Example 1 This embodiment provides a liquid metal ultrasonic energy collection system, such as Figure 1 As shown, it includes a substrate 1, a liquid metal 2, a friction layer and a working electrode 3. The substrate 1 is silicon dioxide with a thickness of 2.5 mm. The liquid metal 2 is placed on the substrate 1. The liquid metal 2 is a gallium indium tin alloy (eGaInSn) composed of gallium (Ga), indium (In), and tin (Sn) in a certain proportion, or one of the two binary combinations of gallium and indium, gallium and tin, or a combination of three elements of gallium, indium, and tin. The friction layer is an oxide layer on the surface of the liquid metal 2, and the thickness of the oxide layer is 0.007 mm to 0.03 mm. The working electrode 3 is a copper electrode with a diameter of 0.06 mm to 0.10 mm, and the working electrode 3 is inserted into the liquid metal 2 through the oxide layer. When used, one end of the load is connected to the working electrode 3, and the other end of the load is grounded.

[0030] like Figure 2As shown, during the test, a 40kHz ultrasonic transducer with a diameter of 50mm and a power of 30W was used, and the non-contact state was 5mm. 10g of eGaInSn was placed in a silica beaker with a bottom diameter of 50mm at room temperature and pressure. The experiment was carried out in single-electrode mode, with a copper electrode (working electrode 3) as a single electrode. The open-circuit voltage peak value tested by the voltage divider method reached 6kV, exceeding that of most nanogenerators, and at the same time generated a current peak of 25μA, corresponding to a calculated power of 150mW. Experiments show that the direct current generated by the present invention directly powers 100 LEDs without the need for a complex rectifier module.

[0031] The core concept of the present invention is that when subjected to ultrasonic mechanical stress, high-frequency dynamic mechanical stress and high voltage promote the micro-displacement and formation of dense wrinkles of the interface core membrane structure under the combined effect of the periodic redox reaction of liquid metal 2 and the interface and internal self-driving characteristics, and realize efficient energy collection through charge separation, contact electrification and electrostatic induction between the hybrid interfaces of the device.

[0032] Figure 3 (ac) Voltage signals when the substrate materials are silicon dioxide, copper, and gallium oxide. In the comparison of the three materials, Ga 2 O 3 The voltage rise rate of the combination with Cu is the fastest, reaching the peak voltage of 6KV within 10s, followed by SiO 2 The combination of Cu and eGaInSn reached the voltage peak in about 20s under ultrasonic environment, and finally the combination of Cu and eGaInSn reached its own platform peak of 3.5KV in about 28s. In addition, we observed that when the liquid metal 2 was not in contact with the copper electrode on the surface of silica glass, air breakdown occurred after the ultrasonic mechanical stress acted on it, and the voltage and current could still maintain a high level. The experimental results were 1.9KV for contact voltage, 2.6KV for non-contact voltage, 5.1μA for contact current, and 2.5μA for non-contact current. Ultrasonic mechanical stress propagates through the air medium, causing violent vibration and collision of air molecules, causing the kinetic energy of air molecules to increase sharply. When the energy accumulates to a certain level, the air molecules are ionized, thereby forming a plasma channel, that is, air breakdown occurs. Figure 3 (d) is the charge signal of the liquid metal ultrasonic energy harvesting system when the substrate is silicon dioxide. From the figure, it can be seen that with silicon dioxide as the substrate, the charge signal of the liquid metal changes with time under the action of ultrasonic high-frequency mechanical stress. The curve shows that the charge value is low in the initial stage, and then gradually increases. Although there are fluctuations, it shows an overall upward trend. The charge signal reaches 20 nC at about 46 seconds, and the charge continues to accumulate over time. After turning off the ultrasound, the mechanical stress disappears and the charge stops accumulating continuously.

[0033] In the implementation process of the present invention, the relative movement between the liquid metal 2 and the silicon dioxide substrate 1 will generate opposite charges on their interface, thereby establishing an interface potential difference. This phenomenon not only supports the energy harvesting function, but also gives the device good mechanical sensing performance. When an external target applies mechanical stress or displacement occurs, the system can respond through changes in open circuit voltage or induced current, so it can be used as a displacement, deformation or stress sensor. Figure 4 To receive voltage and current signals generated by ultrasonic mechanical stress at different angles in the horizontal and vertical directions. When ultrasonic stress acts vertically on the surface of liquid metal 2, the central area is impacted first, forming a pressure gradient that spreads outward. The high pressure in the central area causes the liquid metal 2 to flow toward the periphery, while stretching the oxide layer on its surface. When the tensile stress exceeds the fracture strength of the oxide layer, the area breaks; and the peripheral area forms a concentric ring-shaped wrinkled structure due to stress redistribution. These changes in dynamic curvature cause changes in the ion concentration distribution in the electric double layer at the interface, thereby generating differentiated electrical signal outputs. This mechanism enables the system to have real-time perception capabilities of liquid level height, center point displacement and volume changes. Furthermore, when mechanical stress is applied in the horizontal direction (lateral direction), the liquid metal 2 moves in a direction away from the stress point driven by the pressure gradient. In this process, the oxide layer on the side of the force is locally stretched or even deformed, while the other side is compressed and wrinkled due to the substrate constraint. This asymmetric stress distribution and oxide layer response cause the EDL structure to rearrange, resulting in directional electrical signal output. Therefore, the system described in the present invention can not only realize efficient energy collection, but also can be used to identify various complex sensing functions such as force direction, tilt angle and target distance, showing excellent multi-dimensional response characteristics and functional integration potential.

[0034] In the implementation process of the present invention, the surface characteristics of the liquid metal 2 under the action of ultrasound were quantitatively analyzed by work function test. The experimental results show that the work function of the untreated eGaInSn increased by about 3.4% after 5 minutes of ultrasonic excitation, indicating that ultrasound can effectively enhance the electron escape ability of the liquid metal surface, thereby improving its surface activity. This enhancement contributes to more efficient separation and transmission of interfacial charges, thereby improving energy output efficiency. Furthermore, after 10 hours of continuous ultrasound, the work function of eGaInSn still showed an increase of about 1.57%. Although the increase slowed down, it still showed that its surface activity had a stable enhancement trend under long-term action. Combined with X-ray photoelectron spectroscopy (XPS) analysis, it was found that the change in work function was closely related to the slight fluctuation in the thickness of the oxide layer on the surface of the liquid metal 2. The dynamic regulation of the oxide layer not only affects the electron migration behavior, but also plays a key role in the intensity and stability of the output signal. In addition, the experiment also observed that after the ultrasound stopped, the surface activity of the liquid metal could gradually recover to a state close to the initial state over time, showing obvious self-healing properties. This characteristic shows that eGaInSn not only has surface activation ability under ultrasonic excitation, but also has good interface recovery ability, which helps the system maintain stable performance and continuous output during long-term operation or multiple excitations. This phenomenon further verifies the core role of the oxide layer in electrical signal generation and system stability.

[0035] Figure 5 The change of contact angle of the liquid metal ultrasonic energy collection system before and after ultrasonic treatment, wherein i) has never been subjected to ultrasonic treatment, and ii) has been subjected to ultrasonic treatment for 10 hours. It can be seen from the figure that there is no significant change in contact angle before and after ultrasonic treatment, indicating that the present invention has high stability. In addition, the inventors also measured the work function, voltage, and XPS before and after ultrasonic treatment, and there was no significant change, which also shows that the present invention has high stability.

[0036] Preferably, silicon dioxide fibers are provided at the bottom of the liquid metal 2. Under the action of ultrasound, the silicon dioxide fibers can better adapt to deformation, promote more dynamic changes between the surface of the liquid metal 2 and the oxide layer, help to improve charge separation and potential difference, and thus improve energy collection efficiency.

[0037] Preferably, the head of the copper electrode has a thinner connection portion. Under the action of ultrasound, the working electrode 3 of the head is prone to vibrate, so that the contact surface between the working electrode 3 and the liquid metal 2 generates greater local stress. This local stress change promotes the fracture, wrinkling and reorganization of the oxide layer on the surface of the liquid metal, thereby enhancing the separation of charges and the change of potential difference, thereby improving the energy conversion efficiency.

[0038] Preferably, the liquid metal 2 is doped with precious metal particles, such as gold microparticles, which help the liquid metal 2 to more effectively undergo dynamic deformation or vibration under ultrasonic excitation, thereby enhancing the dynamic characteristics of the interface and improving the energy collection efficiency.

[0039] Example 2 This embodiment provides a method for preparing a liquid metal ultrasonic energy collection system, comprising the following steps: Step 1: Cleaning the substrate 1 with plasma.

[0040] Specifically, the silicon dioxide substrate 1 is placed in a plasma cleaning device, an appropriate amount of cleaning gas (such as oxygen, argon, etc.) is introduced, and appropriate cleaning power, frequency and time parameters are set. Generally speaking, the power can be set between 100-500 watts, the frequency is about 13.56 MHz, and the cleaning time is 5-15 minutes. Under the action of plasma, the gas is ionized to produce a plasma cloud, in which the high-energy particles react physically and chemically with the pollutants on the surface of the silicon dioxide substrate 1 to remove the pollutants, thereby achieving the purpose of cleaning the silicon dioxide substrate 1.

[0041] Step 2: Carrying liquid metal 2 on substrate 1.

[0042] Specifically, a certain amount of liquid metal 2 is accurately sucked by a micro-syringe, and it is slowly dripped on the center of the silicon dioxide substrate 1 after plasma cleaning. To ensure that the liquid metal 2 can be evenly spread and stably attached, some micron-level grooves or patterns can be made on the substrate surface in advance by photolithography technology. These grooves or patterns can guide the flow direction of the liquid metal, so that it is distributed according to the designed shape, avoiding random diffusion, and greatly improving the controllability of the distribution of the liquid metal 2 on the substrate 1, which is extremely critical for subsequent research on the performance of the liquid metal 2 under specific conditions. At the same time, during the dripping of the liquid metal 2, the substrate 1 is placed on a platform with a slight vibration function, and the low-frequency vibration of 1-2 times per second is used to prompt the liquid metal 2 to fill the groove or pattern faster and more evenly, further improving the uniformity of its distribution on the substrate, and the evenly distributed liquid metal 2 can provide a more stable and reliable data basis for subsequent electrical, thermal and other tests. In addition, the functions of the grooves or patterns in other aspects are as described above, and they will not be repeated again.

[0043] Step 3: inserting the working electrode 3 into the liquid metal 2.

[0044] Specifically, the copper electrode is pretreated before being inserted. The copper electrode is soaked in a dilute hydrochloric acid solution for 5-10 minutes to remove the oxide layer on the surface, then rinsed with deionized water and dried under a nitrogen atmosphere. This treatment ensures that the copper electrode has good conductivity, laying the foundation for subsequent stable connection with the liquid metal.

[0045] During the experimental test, the negative electrode of the electrometer (Keithley 6514) was accurately connected to the grounded metal. The core principle of this connection method is to use the earth as a huge charge reservoir to provide a stable potential reference point for the entire circuit. By connecting the negative electrode of the electrometer to the grounded metal, the charge in the circuit can form a complete flow path between the liquid metal, the copper electrode, the electrometer and the grounded metal, ensuring that the current can be smoothly conducted, thereby ensuring the accuracy and stability of the electrical parameter measurement during the experiment.

[0046] In summary, the present invention provides a liquid metal ultrasonic energy collection system. The present invention utilizes ultrasonic external field stress drive, and the liquid metal 2, based on the oxide layer and its own liquid, flexible, and self-healing properties, can form and enhance charge separation at the interface, generating a unidirectional output DC electron flow. The liquid metal non-contact sensing self-healing high-voltage DC generator proposed in the present invention can continuously sense and accumulate low-frequency sound wave energy in a zero power consumption state. When demand increases, the seamless coupling effect of ultrasound can significantly amplify the power output and meet the needs of efficient energy conversion. At the same time, the self-healing characteristics exhibited by the generator can maintain stable performance during long-term operation.

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

Claims

1. A liquid metal ultrasonic energy collection system, comprising a substrate, liquid metal, a friction layer, and a working electrode, wherein the liquid metal is placed on the substrate, and characterized in that: The friction layer is an oxide layer on the surface of the liquid metal, and the working electrode is inserted into the liquid metal through the oxide layer; when used, one end of the load is connected to the working electrode, and the other end of the load is grounded.

2. The liquid metal ultrasonic energy collection system according to claim 1, characterized in that: The substrate is silicon dioxide.

3. The liquid metal ultrasonic energy collection system according to claim 2, characterized in that: The thickness of the substrate is 2 mm to 3 mm.

4. The liquid metal ultrasonic energy collection system according to claim 1, characterized in that: The liquid metal is a gallium-indium-tin alloy, or is formed by a binary combination of indium, gallium and tin, or is formed by a combination of indium, gallium and tin.

5. The liquid metal ultrasonic energy collection system according to claim 1, characterized in that: The material of the working electrode is copper.

6. The liquid metal ultrasonic energy collection system according to claim 5, characterized in that: The diameter of the working electrode is 0.06 mm to 0.10 mm.

7. The liquid metal ultrasonic energy collection system according to claim 1, characterized in that: The thickness of the oxide layer is 0.007 mm to 0.03 mm.

8. A method for preparing a liquid metal ultrasonic energy collection system, characterized in that: The steps include: Step 1, using plasma to clean the substrate; Step 2, carrying liquid metal on the substrate; Step 3: Insert the working electrode into the liquid metal.

9. A method for preparing a liquid metal ultrasonic energy collection system as claimed in claim 8, characterized in that: The step 2 also includes providing micron-scale grooves or patterns on the substrate.

10. A method for preparing a liquid metal ultrasonic energy collection system as claimed in claim 9, characterized in that: The step 3 also includes removing the oxide layer on the surface of the working electrode.

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