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Since shape memory alloys have been recognized to be a smart material, actuator elements based on the shape memory effect have been increasingly used in various ®elds of application. This paper reports on the design and fabrication of several silicon microactuators driven by shape memory elements, namely mechanical microgrippers, microvalves and arti®cial muscle actuators. The actuators were designed as compliant mechanisms and fabricated by silicon micromachining. For the processing of the shape memory elements a new laser assisted technology was applied. The shape memory elements were connected to the silicon mechanisms either by positive joining or by adhesive bonding.

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Three innovative micro actuator concepts on the basis of the differential SMA principle are presented in this paper: a high adaptive multi-actuator system, which is driven by numerous identical single actuators connected in parallel and in series, a micro gripper for handling and assembling of complex hybrid micro systems and a micro actuator system in medical tools for the percutaneous resection of aortic valves. The SMA material is used in the form of 50 lm thin NiTi foils because of their well-defined properties and high strength. In order to integrate them into micro systems, different manufacturing methods have been applied and improved at the Institute for Microtechnology. Laser cutting and wet chemical etching are used for example to microstructure the actuator elements. Different methods for electrical and mechanical connections of the actuators are employed like soldering by the use of an additional gold layer. A batch fabrication process of SMA actuators is realized by embedding NiTi foil elements into SU-8 structures. To optimize the design of SMA actuator elements according to its application different simulation procedures are used.