Characteristics of a highly symmetrical miniature capacitive triaxial accelerometer

A highly symmetrical cubic capacitive triaxial accelerometer for biomedical applications has been designed, realised and tested. The sensors are available in two outer dimensions, namely 2/spl times/2/spl times/2 and 5/spl times/5/spl times/5 mm/sup 3/. The devices are mounted on a standard IC package for easy testing. Features of the sensor are a highly symmetrical cubic structure, capacitive coupling of the high frequency input voltage to the seismic mass and the use of the polymers polydimethylsiloxane (PDMS) as spring material between the capacitor plates and the mass and polyimide (PI) as flexible interconnection layer between the capacitor plates. The sensor structure and its basic operating principle, its mathematical mass-spring-damper model and the necessary cleanroom technology are described. The measurement results show a sensitivity of /spl sim/0.15 V/(m/s/sup 2/) with a corresponding resolution of 0.01 m/s/sup 2/, an off-axis sensitivity of <5 %, a good linearity in the output voltage for accelerations up to at least 50 m/s/sup 2/ and a bandwidth of DC 500 Hz.

[1]  P. Bergveld,et al.  Polydimethylsiloxane, a photocurable rubberelastic polymer used as spring material in micromechanical sensors , 1997 .

[2]  P. Bergveld,et al.  Theory, technology and assembly of a highly symmetrical capacitive triaxial accelerometer , 1997, Proceedings IEEE The Tenth Annual International Workshop on Micro Electro Mechanical Systems. An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots.

[3]  M. Esashi,et al.  Three-axis Capacitive Accelerometer With Uniform Axial Sensitivities , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[4]  K. Okada.  Tri-Axial Piezoresistive Accelerometer , 1992 .

[5]  M. K. Andrews,et al.  A comparison of squeeze-film theory with measurements on a microstructure , 1993 .

[6]  Joost Conrad Lötters,et al.  Design, realization and characterization of a symmetrical triaxial capacitive accelerometer for medical applications , 1997 .

[7]  Masayoshi Esashi,et al.  Electrostatic servo system for multi-axis accelerometers , 1994, Proceedings IEEE Micro Electro Mechanical Systems An Investigation of Micro Structures, Sensors, Actuators, Machines and Robotic Systems.