V-shaped and Z-shaped SU-8 micro-tweezers with in-plane displacement for micromanipulation

This paper presents the design, simulation, measurements, and experimental testing results of two micro-tweezers fabricated using SU-8 polymer as structural material. The micro-tweezers are electro-thermally actuated with a V-shaped and Z-shaped actuator, respectively. The micro-tweezers are in the normally closed mode operation. The structures were simulated using the finite element method within Coventorware software in order to determine their electro-thermo-mechanical behaviors. Electro-thermo-mechanical measurements and characterizations have been performed to determine the openings and the temperature distribution in the micro-tweezers as a function of electrical current. The measurements show a maximum in-plane opening of 61 μm between the tips of the V-shaped micro-tweezer at an electrical current of 53.7 mA while for the Z-shaped micro-tweezer an opening of 80 μm was obtained for at 54 mA. In both cases the out-of-plane deflection remains below 0.1 μm during actuation. A comparison between the simulations results and the measurements has been made. Functional tests were performed in order to prove the capability of the micro-tweezers by performing pick-and-placement operations to manipulate glass beads as the micro-objects.