DESIGN, FABRICATION AND CHARACTERIZATION OF A HIGHLY SYMMETRICAL CAPACITIVE TRIAXIAL ACCELEROMETER

A highly symmetrical cubic capacitive triaxial accelerometer for biome dical applications has been designed, fabricated and characterized. Th e outer dimensions of the sensors are 5 mm x 5 mm x 5 mm. The devices are mounted on a standard IC package for easy testing. Features of the triaxial accelerometer are a highly symmetrical cubic structure, capa citive coupling of the high-frequency input voltage to the seismic mas s, and the use of the polymer polydimethylsiloxane (PDMS) as spring ma terial between the capacitor plates and the mass and polyimide (PI) as the flexible interconnection layer between the capacitor plates. The sensor structure and its basic operating principle, its mathematical m ass-spring-damper model and the cleanroom technology necessary for the fabrication of the devices are described. The measurement results sho w a sensitivity of similar to 0.2 V (m s(-2))(-1) with a corresponding resolution of 0.01 m s(-2). an off-axis sensitivity of < 5%, a good l inearity in the output voltage for accelerations up to at least 50 m s (-2) and a bandwidth of d.c. to similar to 1 kHz. (C) 1998 Elsevier Sc ience S.A. All rights reserved.