A Thermally actuated four-legged MEMS based Silicon Micro-robot

In this paper we propose the design and concept of a thermally actuated MEMS based Silicon micro-robot. The micro robot is a thermally actuated cantilever beam based structure where four beams act as the arms of the robot which are attached to a central mass. Each cantilever beam is 1.75 mm in length, 200µm in width and 500µm in height. The robot is 3.8 mm long, 4mm wide and has a height of 500µm. Each cantilever beam has resistors doped on them which act as heaters. The design of the cantilever beams is such that they have narrow trenches on the dorsal side where a positive coefficient of Thermal Expansion (CTE) polyimide material is deposited. When polyimide is cured it shrinks and therefore the beam bends downwards. When a current is applied through the heaters the polyimide heats up and expands. The sequential expansion and shrinking of polyimide causes an actuation sequence which enables the motion of the micro-robot. This robot was inspired from nature where small size enables small organisms to crawl in hard to reach places. Based on the same principle, micro robots can be deployed in high risk situations involving search and rescue. Micro robots also have a great potential in the field of medicine, especially for applications like minimal evasive surgery, remote drug delivery and medical diagnosis[1].Micro robots are promising especially in the field of space exploration as they can be mass bulk fabricated and can fit in small enclosures where volume and size are big constraints[2] In this paper we are emphasizing on the fabrication of such a micro-structure.