Mechanically driven microtweezers with integrated microelectrodes

This paper presents a method for fabricating a fundamental MEMS tool-microtweezers. Microtweezers offer an attractive option to meet the increasing need to grasp, manipulate and excise microstructures or biological components. The microtweezers presented here augment a standard micromanipulator, allowing precise positioning in three dimensions. An additional micro-drive control knob, which is affixed to the micromanipulator, allows actuation of the tweezer tips through the use of a tether-cable drive system. This drive actuates the tweezer tips by the reciprocating motion of two microfabricated parts: the tweezers and tweezer box. A simple three-layer planar fabrication scheme allows for a broad range of tweezer styles (straight and serrated tips) and sizes (microns to millimeters). For these studies, 20 mu m wide and 10 mu m thick nickel beams were developed for the tweezer tips, which could endure 20 mN of force. To demonstrate the concept of microassembly, pick and place operations were performed on 10 mu m thick film structures. Additional functionality was achieved by integrating platinum-black microelectrodes into parylene-coated tweezers to allow electrophysiological functions such as cellular stimulation and recording. Ultimately, this unique and simple design affords extraordinarily delicate control that is potentially beneficial for applications in microassembly, electrophysiology and microsurgery.