Ramaswamy Mahadevan

A novel two axis actuator for high speed large angular rotation

Reports the development of a novel two axis rotary actuator capable of high frequency out-of-plane rotation in two fully independent axes with large angular excursions. Initial results indicate that using the novel suspension and actuation mechanism presented permits large rotations exceeding /spl plusmn/13.5 degrees at rotational speeds exceeding 15 kHz, using excitation voltages below 100 V. The device is fabricated using a combination of surface and bulk micromachining. In this work the actuators are used to rotate single crystal silicon plates of sizes up to 1 mm/sup 2/. The size of such a device is less than 4 mm/sup 2/ making it suitable for a variety of new applications, such as micropositioning systems, inertial systems, microoptical elements, and compact imaging systems.

MEMS 2D matrix switch

Microelectromechanical systems, or MEMS, are among several promising technical approaches to implementing all-optical switching in telecom and data networks. At the core of MEMS switches is an array of micromirrors capable of redirecting light either in free space or within a waveguide framework. The 2D switch architecture as shown in figure I employs one mirror for every possible switched node in a matrix switch, and thus requires N/sup 2/ mirrors for an NXN array. 2D mirror arrays are characterized by two-state mirror positioning. One state is inactive and requires only that the mirror can be parked out of the optical path.

Thin-film thermoelectric energy harvesting for security and sensing applications

The past decade has seen significant advances in distributed sensors and sensor networks. Many of these advances have been driven by programs that support national intelligence and security interests. With these advances have come an increased interest in energy harvesting to provide continuous power sources to replace or augment existing power storage systems. The use of waste heat is an attractive source of energy for many applications where μW-mW power is required. The implementation of a thermoelectric power conversion system requires several basic elements in addition to an assumed heat source. These elements are: 1) a thermoelectric device, 2) a heat sink, 3) voltage regulation, 4) an energy storage device and 5) load management. The design and optimization of the system (and each element within the system) is highly dependent on the thermal boundary conditions and the power load. This presentation will review the key performance factors and considerations required to optimize each element of the system to achieve the required I-V characteristics for output power.