A study of the enhancement of the mechanical sensitivity of an area-changed capacitive accelerometer by optimization of the device geometry is presented. The movable mass of the accelerometer was designed with many fingers connected in parallel and suspended over the stationary electrodes composed of differential comb fingers by means of mechanical beams anchored onto the substrate. The maximum displacement possible based on the chosen design structure was determined. From this displacement value the spring constant was calculated, and based on this spring constant value various combinations of the beam length and width were selected. The lengths and the widths were then varied and simulated using the Coventorware 2001.3 software. This was done as theoretical analysis showed that the mechanical beam dimensions are significantly more dominant in the overall device sensitivity. The displacement and spring constant variations with the beam dimensions at an applied acceleration was observed and analyzed. The same process was done for the number of fingers, length and thickness of each finger. Each of these was done in isolation based on the optimum geometry of the mechanical beams and tested to ensure that alterations of these aspects do not have a significant effect on the overall sensitivity. The modal and harmonic analysis were also simulated and observed to ensure the linearity and the stability of the dominant mode of the operation of the device. Optimum results of the device geometry are presented and discussed, along with suggested next steps.
[1]
Stephen F. Bart,et al.
An integrated force-balanced capacitive accelerometer for low-g applications
,
1996
.
[2]
H. Jerman,et al.
Wide dynamic range direct accelerometer
,
1990,
IEEE 4th Technical Digest on Solid-State Sensor and Actuator Workshop.
[3]
Francis E. H. Tay,et al.
A differential capacitive low-g microaccelerometer with mg resolution
,
2000
.
[4]
N. Yazdi,et al.
A high sensitivity capacitive microaccelerometer with a folded-electrode structure
,
1999,
Technical Digest. IEEE International MEMS 99 Conference. Twelfth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.99CH36291).
[5]
Yeop M. Burhanuddin,et al.
Area-changed capacitive accelerometer using 3-mask fabrication process
,
2004,
SPIE Micro + Nano Materials, Devices, and Applications.
[6]
Farrokh Ayazi,et al.
Micromachined inertial sensors
,
1998,
Proc. IEEE.
[7]
Byeungleul Lee,et al.
A Capacitive Silicon Microaccelerometer With Force Balancing Electrodes
,
1998,
Digest of Papers. Microprocesses and Nanotechnology'98. 198 International Microprocesses and Nanotechnology Conference (Cat. No.98EX135).
[8]
Weiyuan Wang,et al.
Micromachined accelerometer with area-changed capacitance
,
2001
.