Ph.D. Proposal Presentation by Rajesh Luharuka
Friday, November 12, 2004

(Dr. Peter J. Hesketh, Chair)

"Investigation of the Use of a Fully Compliant “Rotationally Bistable” Micromechanism With an Integrated Electromagnetic Actuator for High-flow Microvalve"


Tremendous interest in miniaturizing of gas chromatography system and other Lab-On-The-Chip devices used for gas based chemical analysis and biotechnological assays has created need for an integrated microvalve that can support high-flow rate, has fast response time, has low switching energy, and still has low leakage ratio. In the conventional diaphragm-type microvalves, the overhanging diaphragm with a gap size of 5-30 µm is equivalent to a converging-diverging duct geometry, which greatly limits the maximum achievable flow rate for a compressible medium. These microvalves experience high pressure drop that increases the power consumption of the system for multiple reasons. Furthermore, squeeze film damping in such parallel plate geometry makes valve closing difficult and slow.
This proposal presents a new design of an electromagnetically actuated microvalve that is suitable for high flow rate applications, has fast response time, requires low energy to switch, and has low leakage ratio. The microvalve comprises of an inductor integrated with an in-plane rotationally bistable diaphragm fabricated of a soft magnetic material. The diaphragm designed to rotate in-plane between its bistable positions is actuated actuated by an integrated inductor to open and close the inlet/outlet ports on the substrate. The proposed microvalve design overcomes the limitations of the diaphragm-type microvalves by providing an unrestricted fluid flow path in the open state. The microvalve is designed to function as bypass valves in micro gas chromatography systems reported in the literature, which is used during sample collection. The in-plane rotating mechanism designed for the microvalve membrane also has applications in Opto-MEMS such as optical switches and micro-optical shutters.
Design and implementation of a fully compliant rotationally bistable micromechanism is a significant area of research, which will involve accurate modeling and optimization techniques. Furthermore, integration of such a mechanism with an on-chip electromagnetic actuation is a challenging research problem in terms of design and fabrication. Finally, the theoretical analysis will be supported by performance evaluation through the testing of the micromechanism for bistability and the microvalve for micro gas chromatography application.