No-power vacuum actuated bi-stable MEMS SPDT switch

A "No-power" MEMS based vacuum/pressure actuated single pole double throw (SPDT) switch is presented. Compressive stresses in thermal oxide and TiW layer provide pre-stress in the polyimide mechanical films that initiates diaphragm buckling upon release. The diaphragms are bi-stable in nature with a buckling height greater than 28 μm. These bi stable diaphragms were incorporated into a MEMS based no power SPDT switch which comprises of 2 series single pole single throw (SPST) switches. Pressure/vacuum was used to actuate the diaphragms and OPEN/CLOSE the series SPST switches. The actuation or switching pressure/vacuum of the SPST switches was determined to be greater than 40 KPa which compares favorably with the analytical model predictions. The contact resistance of the MEMS SPST switches was determined to be less than 200 Ω. The proposed no-power switches are passive, programmable, monolithic, and small and can find several applications in the field of MEMS. Also, the polyimide diaphragms can be used as the fundamental building blocks in micro-pumps, micro-valves, optical devices and energy harvesting devices which require large cyclic displacement. Because of their bi-stable nature, the diaphragms can also be used for applications in mechanical memory storage.