An Aluminum Electro-Thermally Actuated Micro-Tweezer: Manufacturing and Characterization.

In this paper, we present the investigations of an aluminum micro-tweezer designed for micromanipulation applications. It includes design, simulation, fabrication, characterizations, and experimental measurements. Electro-thermo-mechanical FEM-based simulations using COMSOL Multiphysics were performed to describe the behavior of the micro-electro-mechanical system (MEMS) device. The micro-tweezers were fabricated in aluminum, as structural material, by surface micromachining processes. Experimental measurements were performed and compared with the simulation results. A micromanipulation experiment was performed using titanium microbeads from 10-30 µm to confirm the performance of the micro-tweezer. This study serves as further research regarding the using of aluminum as structural material for MEMS devices designated for pick-and-place operations.

AFM Characterization of Temperature Effect on the SU-8 Mechanical and Tribological Properties.

This study presents the effect of temperature on the mechanical and tribological properties of SU-8 polymer. The temperature of investigated samples increasing during testing and the variation of mechanical and tribological properties were monitored. The samples for tests were SU-8 hard baked at different temperatures. The hard bake temperature changes the mechanical and tribological properties of polymers. The aim of this research work is the reliability design improvement of SU-8 microstructures from electro-thermally actuated devices where a thermal gradient produces the softening and modification of SU-8 behavior. As a function of the hard baked temperature, different mechanical and tribological properties were experimentally determined using the atomic force microscopy (AFM) technique. The mechanical properties of interest are the modulus of elasticity and hardness. The investigated tribological properties involve the adhesion and friction forces. The modulus of elasticity and hardness decrease if the operating temperature increases based on the thermal relaxation of material and their viscoelastic behavior. The adhesion force between AFM tip and investigated samples increases if the operating temperature increases, respectively. The same evolution was experimentally observed in the case of friction force. Moreover, for the same testing temperature, the modulus of elasticity and hardness increase, and the adhesion and friction forces decrease if the SU-8 is hard baked at high temperature.