Many critical applications in microelectromechanical systems (MEMS) require that certain components be capable of being in two or more distinct and predictable positions. Examples include electrical relays and switches, microfluidic valves, microfluidic pumps, hydraulic spool valves, micro positioning of optical arrays, and mechanical switches for fiber optic circuits or other applications. Currently, most devices used in such applications have the rest position at one state such that power must be continuously supplied to the device to maintain the second position. The high energy requirements of these methods limit their practicality for large autonomous MEMS devices and arrays. Bistable devices offer an innovative alternative because they have two stable equilibrium positions. Energy input to the system is required only during the transition from one stable equilibrium position to the other. This is important for both autonomous systems that must carry their own power supply and for devices where heat must be minimized. Other major advantages of bistable mechanisms include the ability to maintain state for extended periods regardless of the status of the input power source (this is important for nonvolatile memory and other applications), and increased accuracy and precision in positioning of micro devices. Compliant mechanism theory offers the means to design successful bistable mechanisms at the micro level. Many MEMS already use flexures and other simple compliant components, but compliant mechanism theory makes possible much more complex mechanical motion. Because motion and energy storage are integrated in compliant mechanisms, they are ideal for bistable devices. The proposed approach includes the following: bistable configuration identification; modeling, analysis, and design; actuation; fabrication and testing.
