SMA microgripper system

A microgripper system is presented, which consists of a monolithic shape memory alloy (SMA) device of 2 mm x 5.8 mm x 0.23 mm size and an integrated optical position sensor. Gripper closing and opening is performed by two integrated actuators, which form an antagonistic pair. Investigations of temperature profiles by coupled finite-element simulations and infrared microscopy demonstrate a sufficient thermal insulation of the actuators for their selective control. The motion of gripping jaws is transmitted by an integrated gearing mechanism into a linear motion of an integrated optical slit, which is detected by change of optical transmission. The maximum stroke and force of the gripping jaws are 300 mum and 35 mN, respectively. In the range between 10 and 90% of the maximum stroke, positioning is achieved within 140 Jus with an accuracy of about 2 mum. (C) 2002 Elsevier Science B.V. All rights reserved.