A sensorized μelectro discharge machined superelastic alloy microgripper for micromanipulation: simulation and characterization

This paper describes a novel microgripper, fabricated in superelastic alloy (Ni50.8Ti49.2) by wired micro Electro Discharge Machining (μEDM). The main features of the new microgripper are fabrication technology (μEDM) and exploited material (superelastic alloy); the gripper was sensorized with commercial semiconductor strain-gauges and implemented in the force-feedback micromanipulation workstation developed in the authors’ laboratory. Both FEM simulation and results of experimental characterizations are presented. Introduction This microgripper was designed by exploiting the know-how acquired through previous activities on micromanipulation and microtools in the authors’ laboratory, when LIGA and laser machined grippers in nickel and steel were used [1]. The microgrippers fabricated in nickel by exploiting the LIGA technique were based on mechanical flexure joints; slightly different designs were used to obtain different mechanical performances. Essentially two different sets of microgrippers were fabricated: the average size of the microgrippers are 7 x 15 x 0.4 mm for the first set; and 10 x 25 x 0.2 mm for the second set. LIGA fabricated grippers were all actuated by PZT (high and low voltage) and were sensorized by commercial semiconductor strain-gauges in order to provide a force feedback signal to the operator [2]. After proper calibration the maximum forces generated by the gripper were 22 and 7 mN for the first and the second set, respectively [3,4]. As shown in Table 1 below, we compared the main features of the grippers with those of a commercial one (Bartels Mikrotechnik GmbH), devoted to similar applications.