Jizhu Liu

Since the cell was discovered by humans, it has been an important research subject for researchers. The mechanical response of cells to external stimuli and the biomechanical response inside cells are of great significance for maintaining the life activities of cells. These biomechanical behaviors have wide applications in the fields of disease research and micromanipulation. In order to study the mechanical behavior of single cells, various cell mechanics models have been proposed. In addition, the measurement technologies of single cells have been greatly developed. These models, combined with experimental techniques, can effectively explain the biomechanical behavior and reaction mechanism of cells. In this review, we first introduce the basic concept and biomechanical background of cells, then summarize the research progress of internal force models and experimental techniques in the field of cell mechanics and discuss the latest mechanical models and experimental methods. We summarize the application directions of cell mechanics and put forward the future perspectives of a cell mechanics model.

To meet the application requirements of a thermal gas sensor, it is necessary to realize a bond connection between PtW8 wire with a Au thick film. However, the physical properties, such as the melting point and hardness, of the two materials differ greatly. In this study, the parallel-gap resistance microwelding was introduced into the bonding connection between PtW8 wire and a Au thick film in the thermal gas sensor. The feasibility of the method was analyzed theoretically and the experimental system was established and studied. A scanning electron microscope (SEM) was used to analyze the morphology of the cross-section of the welded joint. The results showed that there was no obvious transition layer at the interface region but there were relatively dense welds. At the same time, it was found that the melted Au wetted and climbed on the surface of the platinum-tungsten alloy, which may have been the key to forming the joint. Elements were observed to have a spatial distribution gradient within the cross-section of the welding line, revealing that mutual diffusion occurred in the parallel-gap resistance microwelding, where this diffusion behavior may be the basic condition for forming the joint. Finally, the influence of the welding voltage, time, and force on the joint strength was also studied, where the joint strength could be up to 5 cN.

Humidity detection range is an important indicator for measuring the performance of humidity sensors, but semiconductor humidity sensors often face the problems of narrow detection ranges and insufficient detection sensitivities. In this paper, a magnesium oxide (MgO) humidity sensor based on micro-arc oxidation (MAO) technology was designed to solve these problems by simultaneously using impedance and capacitance as the response signals, as well as by normalizing the output of the two signals. The experimental results showed that the average output of the micro-arc MgO ceramic film, with impedance as the response signal, could reach 150 in the low relative humidity(RH) range (11.3–67% RH), which was much higher than its sensitivity in the high humidity range (< 1), and the film showed fast response (13 s) and recovery (61 s). Under high humidity conditions (67–97.3% RH), with capacitance as the response signal, the output of the micro-arc MgO was as high as 120. Therefore, the micro-arc MgO humidity sensor with impedance, and the sensor with capacitance as the response signal, demonstrated good stability in low humidity and in high humidity environments, respectively, indicating that the method of selecting appropriate response signals for different humidity environments can be applied to extend the humidity detection range of sensing material, and to improve the humidity detection capability of a sensor.