Utilization of surface tension and wettability in the design and operation of microsensors

The behavior of fluid droplets contained within shaped capillaries and voids can be utilized to convert forces acting upon the droplets to observable displacements which accurately and reproducibly quantify these forces. The position of droplets within such micro-sensors is governed by surface tension, wettability, and the geometric configuration of the confining walls. These micro-sensors have no mechanical moving parts to wear out and are inherently immune to many orders-of-magnitude over-actuation. If non-wetting fluids are employed, the micro-sensors can also be made to operate as micro-valves, micro-switches, optical micro-shutters and irises, as well as other devices. Both circular and non-circular confining structures can be employed. (C) 2000 Elsevier Science B.V. All rights reserved.