2-DIMENSIONAL MICRO-SELF-ASSEMBLY USING THE SURFACE-TENSION OF WATER

Several self-assembling microstructures have been fabricated, and appr oximately 100 units floating on the surface of water have been self-as sembled two-dimensionally. The basic assembly units are 400 mu m in di ameter, and consist of both polyimide and polysilicon thin films. Surf ace tension is used as the bonding force in this system. The surface t ension is the local interaction between the units, and is dominant on the microscale. Each unit is bonded selectively by employing the follo wing characteristics of the surface tension: (1) objects located at eq ual heights are attracted to each other; (2) large attractive forces a ct on sharp parts; and (3) objects located at different heights are mu tually repulsed. The curling-up property of the thin films is used to obtain the different heights. We control the curling-up curvature by t he thickness of the polysilicon layer. Self-assembling behaviour is al so predicted by using a rate equation.