In the present study, high-Tc superconducting thin YBa2Cu3O7 films and polysilicon films were prepared to investigate the initial sliding friction properties using a ball-on-flat tribometer when samples were moved against a sapphire ball or a steel ball in ambient environment. The surface topography was measured with atomic force microscope (AFM). After five times testing, the experimental results indicate that the friction coefficient of YBa2Cu3O7 films is lower than that of polysilicon films when sliding against a sapphire ball and almost the same when sliding against a steel ball. In particular, the initial friction of YBa2Cu3O7 films is more stable when sliding against a sapphire ball. However, the initial friction of polysilicon films fluctuates during a cycle period when sliding against a sapphire ball. They are both stable when sliding against a steel ball. Although, the surface profile of the YBa2Cu3O7 film is rough and can be seen to be rougher than the polysilicon film, but the friction coefficient of the YBa2Cu3O7 film is lower than that of polysilicon film. Also, although the topography of YBa2Cu3O7 films changes during friction, the friction coefficients are stable. This clearly shows that the initial sliding friction of YBa2Cu3O7 films under microfriction is stable. The observation signifies YBCO film is a good film to prevent stick-slip motion in ambient environment. The wear properties of YBa2Cu3O7 films suggest that the superconducting outgrowths (CuO) are loose and they can be easily removed.

A new microtensile test device using a magnetic-solenoid force actuator was developed to evaluate the mechanical properties of microfabricated polysilicon thin films that were 100-660mm long, 20-200mm wide, and 2.4-mm thick. It was found that the measured average value of Young's modulus, 164 GPa

A molecular dynamics simulation is used to investigate the effect of surface roughness on the nano-rheology of ultra-thin films confined between two solid walls. The results show that friction is sensitive to the confining surface morphology and the fluid molecules near the two confining surfaces are in a layering solid-like structure. At a high shear rate, the interfacial layers of the film stick to the walls, resulting in partial slip inside the film and the development of shear stress in the viscous molecular fluid. The frictional resisting force is due to the shear in the viscous molecular fluid but not dependent on the critical yield stress of the solid-like structure as in the case of smooth boundaries.

For the purposes of pressure measurement at high temperature in oil drilling industry as well as in other industrial measurement and control systems, the strain gauge chip of piezoresistive pressure sensor is designed based on separation by implanted oxygen (SIMOX) SOI (silicon on insulator) technology, and then fabricated in the micro-machining work bay. Some kinds of sensor mechanical structures are designed for different customers and conditions. The thermal coefficients of expansion (TCE) mismatches between different materials within the highpressure sensor system are investigated. The sensor is fabricated successfully by using high temperature packaging process. The temperature coefficient of sensitivity (TCS) and temperature coefficient of offset (TCO) compensation circuitry is demonstrated. Based on experimental data, the sensor is tested with high accuracy and good stability.

The increasing use of small micromechanical devices and advanced sensors has led to concern about the failure modes and reliability of these structures. The enormous promise will not materialize without substantial progress in overcoming the stiction, friction and wear associated with such devices and understanding the mechanical behavior of MEMS materials and structures. Self-assembled monolayers (SAMs) are release and anti-stiction coatings for MEMS. In this paper, the anti-stiction properties of octadecyltrichlorosilane (OTS) SAM were calculated. The microtribological properties of OTS SAM were investigated with a ball-on-flat microtribometer. The influence of OTS SAM on the mechanical properties of micromachined polysilicon films for MEMS was investigated with an accurate evaluation using the microtensile test device. It was concluded that the OTS SAM has good anti-stiction properties and low friction coefficients. The hydrophobic property of OTS is the main factor leading to an increase in the average fracture strength of micromachined polysilicon up to 32.46%. Thus, the operational stability and lifetime of MEMS can be raised when coated with self-assembled monolayers.