Using biological principles to design MEMS

In micromechanics the handling and positioning of microparts involves sophi sticated assembly procedures and a good understanding of microtribological phenomena. Due to the very low object mass, adhesion between the micropart and the handling tool (usually a mechanical gripper) becomes a performance- limiting factor. Adhesion effects can be even larger than the force that fr ees the micropart from the handling tool thus making correct positioning im possible. Many useful design principles for optimized adhesion properties c an be found in biological systems. In this paper adhesion between the foot of an insect and a surface was evaluated. The attachment pads of the great green bush cricket (Tettigonia viridissima)-used to attach the insect safel y to a variety of different surfaces-were investigated to draw conclusions that could be implemented in future technical microsystems. It is shown tha t the attachment pads are flexible micromechanical units capable of self-ad justing to different scales of roughness. The erratic influence of capillar y action due to adsorbed water is presumably suppressed by a hydrophobic la yer on the pads. Attaching and releasing mechanisms as well as accurate mea surement of the adhesion force are discussed in detail.