A novel approach to design and fabricate an electrothermal microgripper for cell manipulation

Abstract

Microgrippers are used in cell manipulation, micro-assembly, and material characterization. However, rarely a systematic approach is presented for microgripper design. The current research presents a methodology for single-cell manipulation design and fabricating a MEMS electrothermal microgripper. The result is a list of constraints required for microgripper design. The jaw thickness is defined by simulating oocyte gripping and injecting quantitatively; a genuine approach is presented here. Due to the long list of extracted constraints, a genetic algorithm (GA) is employed to optimize the design to satisfy all constraints. To do so, the required analytical models are developed to be used in the GA. UV- LIGA is employed to fabricate the device with nickel as the structural layer and copper as the sacrificial layer. The microgripper has a compliant structure with a thin layer of titanium and SU8 coated on jaws. The simulation and experimental results shows that the designed structure provides the jaw displacement of 52 µm at the voltage of 0.172 V and a maximum temperature of 75 ºC, with activation and cooling time of 0.3 s (jaw opening and closing). The procedure developed in this research is a systematic approach and can be adopted to design other types of microgrippers for different applications.