Fabrication of All-SiC Fiber-Optic Pressure Sensors for High-Temperature Applications.

Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1-0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature.

Biomimetic Ultrasonic Vibrator with Broadband Characteristics Inspired by Leaf-Cutting Ants.

Power ultrasound is widely used in industrial production, medical equipment, aerospace, and other fields. Currently, there are two main types of commonly used power generation devices: piezoelectric ultrasonic transducers and magnetostrictive ultrasonic transducers. However, in certain situations with limited external dimensions, the applications of existing power ultrasound devices are limited. In nature, leaf-cutting ants excite vibrations through their tiny organs. Inspired by the vibratory organs of leaf-cutting ants, a new type of biomimetic ultrasonic vibrator (BUV) comprising a scraper, dentate disc, and fixture system was proposed, fabricated, and tested in this study. The experimental results showed that the BUV could operate in the frequency range of 16.8-19 kHz. Within the working frequency range, the vibration of the BUV was stable and the amplitude of the vibration displacement was greater than 22 µm. The operating frequency band of the BUV was broader than those of the piezoelectric and magnetostrictive ultrasonic transducers. In addition, the BUV can cut soft rubber and pig tissues with sufficient output power and load-carrying capacity. The BUV, as a new type of power ultrasonic excitation device, is expected to be applied in high-power micro operating scenarios, such as minimally invasive surgical instruments.

Preparation of biosilica structures from frustules of diatoms and their applications: current state and perspectives.

Frustules, the silica shells of diatoms, have unique porous architectures with good mechanical strength. In recent years, biologists have learned more about the mechanism of biosilica shells formation; meanwhile, physicists have revealed their optical and microfluidic properties, and chemists have identified ways to modify them into various materials while maintaining their hierarchical structures. These efforts have provided more opportunities to use biosilica structures in microsystems and other commercial products. This review focuses on the preparation of biosilica structures and their applications, especially in the development of microdevices. We discuss existing methods of extracting biosilica from diatomite and diatoms, introduce methods of separating biosilica structures by shape and sizes, and summarize recent studies on diatom-based devices used for biosensing, drug delivery, and energy applications. In addition, we introduce some new findings on diatoms, such as the elastic deformable characteristics of biosilica structures, and offer perspectives on planting diatom biosilica in microsystems.

High performance drilling of T800 CFRP composites by combining ultrasonic vibration and optimized drill structure.

Drilling of high-strength T800 carbon fiber reinforced plastic (CFRP) are widely employed in current aviation industry. Drilling-induced damages frequently occur and affect not only the load carrying capacity of components but also the reliability. As one of effective methods to reduce the drilling-induced damages, advanced tool structures have been widely used. Nevertheless, it is still difficult to realize high machining accuracy and efficiency by this method. This paper compared three different drill bits to evaluate the drilling performance of T800 CFRP composites and the results showed that the dagger drill was a good choice to drill T800 CFRP considering the lowest thrust force and damages. On this basis, ultrasonic vibration was successfully imposed on dagger drill to further improve the drilling performance. The experimental results showed that ultrasonic vibration reduced the thrust force and surface roughness with a maximum decrease of 14.1 % and 62.2 % respectively. Moreover, the maximum hole diameter errors were decreased from 30 µm in CD to 6 µm in UAD. Besides, the mechanisms of force reduction and hole quality improvement by ultrasonic vibration were also revealed. The results suggest that the combination of ultrasonic vibration and dagger drill is a promising strategy for high performance drilling CFRP.

Improving anti-adhesion performance of electrosurgical electrode assisted with ultrasonic vibration.

The electrosurgical electrode currently stands out as one of the most commonly used tools in minimally invasive surgery. In order to facilitate tissue cutting and accelerate wound healing, tissue adhesion to the electrosurgical electrode is considered as an extremely urgent problem to be solved. In this paper, a novel ultrasonic vibration assisted (UV-A) electrosurgical electrode is firstly proposed to overcome the problem of tissue sticking. The anti-adhesion effects were evaluated by measuring the adhesion force and the weight of tissue adhesion using the electrosurgical electrode with and without UV-A comparatively. Experimental results show that the average adhesion force and the tissue adhesion mass with UV-A were decreased by approximately 60% and 70% respectively, accompanied by smaller thermal injury area compared with that without UV-A. Moreover, the underlying mechanism of anti-adhesion effect with UV-A was revealed by investigating the influence of ultrasonic vibration on electric current, tissue removal and spark discharge. This research suggests that UV-A is a promising and practical method for improving the anti-adhesion performance of electrosurgical electrode.

Study on the separation effect of high-speed ultrasonic vibration cutting.

High-speed ultrasonic vibration cutting (HUVC) has been proven to be significantly effective when turning Ti-6Al-4V alloy in recent researches. Despite of breaking through the cutting speed restriction of the ultrasonic vibration cutting (UVC) method, HUVC can also achieve the reduction of cutting force and the improvements in surface quality and cutting efficiency in the high-speed machining field. These benefits all result from the separation effect that occurs during the HUVC process. Despite the fact that the influences of vibration and cutting parameters have been discussed in previous researches, the separation analysis of HUVC should be conducted in detail in real cutting situations, and the tool geometry parameters should also be considered. In this paper, three situations are investigated in details: (1) cutting without negative transient clearance angle and without tool wear, (2) cutting with negative transient clearance angle and without tool wear, and (3) cutting with tool wear. And then, complete separation state, partial separation state and continuous cutting state are deduced according to real cutting processes. All the analysis about the above situations demonstrate that the tool-workpiece separation will take place only if appropriate cutting parameters, vibration parameters, and tool geometry parameters are set up. The best separation effect was obtained with a low feedrate and a phase shift approaching 180 degrees. Moreover, flank face interference resulted from the negative transient clearance angle and tool wear contributes to an improved separation effect that makes the workpiece and tool separate even at zero phase shift. Finally, axial and radial transient cutting force are firstly obtained to verify the separation effect of HUVC, and the cutting chips are collected to weigh the influence of flank face interference.