Application Cases

Experimental Title: Graphene Preparation

Research Focus: Currently, a wide variety of sensors have been used in intelligent detection equipment. Most of these sensors are based on silicon substrates, such as silicon-based pressure sensors, silicon-based temperature sensors, silicon-based humidity sensors, and silicon-based thermal air velocity sensors. Their application fields have long extended to areas such as production automation, ocean development, smart homes, modern information technology, and military communications. To some extent, sensors can be considered a key factor determining the characteristics and performance indicators of a system. Different requirements also correspond to different sensors to meet the desired accuracy, stability, and durability. Nowadays, research on silicon substrate-based strain sensors has encountered a bottleneck due to the rigidity, brittleness, and fragility of traditional silicon-based electronic devices. Currently, in various applications, sensors are required to be flexible, stable, and stretchable. Therefore, the exploration of using new substances and materials to prepare high-performance strain sensors is urgently needed. However, to endow sensors, electrode materials, and connecting wires with flexibility, bendability, and stretchability, finding materials that inherently possess these characteristics is a key factor in solving this problem. In recent decades, carbon nanomaterials have attracted widespread attention due to their excellent electrical and mechanical properties. Research on organic semiconductors, conductive polymers, carbon nanotubes, and graphene, in particular, which exhibit high electrical conductivity and good biocompatibility, has deepened. These carbon nanomaterials possess excellent physical and chemical properties and have become alternative materials for manufacturing efficient flexible sensors.

Flexible sensors have garnered attention from researchers in various fields. The types of sensors realized , and their application domains are increasingly broad, as shown in the figure. These mainly include wearable electronic devices, human motion sensing, human-computer interaction, health monitoring, electronic skin, and flexible bio-inspired electronic devices. They have demonstrated excellent performance in various fields, successfully meeting every required indicator. Currently, flexible sensors have become a research core and development trend in the field of intelligent sensors.

Experimental Objective: Electrochemical Preparation of Graphene

Test Equipment: Signal generator, ATA-2021B high-voltage amplifier, oscilloscope, Transmission Electron Microscope (TEM), etc.

Experimental Process: Connect the electrode materials (cathode and anode) using copper wires. Then place the electrodes into the aforementioned prepared solution. Connect the other ends of the copper wires to the positive and negative terminals of the DC regulated power supply, respectively. Set a square wave with a peak of 1.6V in the signal generator. Connect the signal generator to the high-voltage amplifier. With an amplification factor of approximately ×16, a ±15V square wave can be obtained. Simultaneously, use the oscilloscope to observe the output voltage of the high-voltage amplifier and control the temperature at 25°C. Turn on the power supply and connect the amplified signal to the electrodes, which are graphite sheet and Pt, respectively. Clean the graphene solution. The electrochemical reduction time is 10 minutes. After graphite exfoliation, clean the resulting graphene solution via centrifugation (the solution is strongly alkaline), repeatedly using deionized water. The experimental process block diagram is shown in Figure 1-1.

Figure 1-1: Experimental Process Block Diagram

Experimental Results: Based on traditional electrochemical graphene preparation methods, a graphite anode oxidation exfoliation method was used, employing a graphite sheet as the anode, Pt as the cathode, and concentrated sulfuric acid and potassium hydroxide as the electrolyte. Anodic oxidation exfoliation for graphene preparation uses graphite as the anode. When the power supply operates, anions in the electrolyte move towards the anode, intercalating into the anode graphite and causing volume expansion due to intercalation. When the volume of the anode graphite increases to a certain extent, it eventually detaches from the bulk material due to the reduction of interlayer van der Waals forces, forming layered graphene or graphene oxide (including single-layer and few-layer graphene oxide with 2-10 layers) containing certain oxygen functional groups. During electrolysis, water at the anode partially decomposes, generating oxygen, which also enters the graphite interlayers. The combined action of both leads to drastic volume expansion of the graphite and final detachment from the surface. This method is simple, pollution-free, and yields high-quality graphene. The prepared graphene dispersion was characterized using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM), revealing the nanostructure and morphology of the graphene.

Figures 1-2 (b) - (d) show TEM characterization images of the graphene dispersion at different scales. These images reveal the nanostructural features of the electrochemically exfoliated graphene. Selecting the diffraction boundary region in Figure 1-2 (b) and magnifying it in Figure 1-2 (c), we can observe that the number of graphene layers is 6-8. Therefore, this graphene sample is few-layer graphene (less than 10 layers). Figure 1-2 (d) is a high-resolution image showing the hexagonal lattice structure, presenting a honeycomb pattern, proving that the graphene material prepared by this method has excellent structural properties.

Figure 1-2: Physical image of the graphene dispersion and TEM characterization images of the graphene dispersion at different scales. (a) Physical image of the graphene dispersion; (b) Diffraction boundary region; (c) Magnified view of (b); (d) Hexagonal lattice structure of graphene.

Voltage Amplifier Recommendation: ATA-2021B

Figure: ATA-2021B High-Voltage Amplifier Specifications and Parameters

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