Lateral CMOS-MEMS Accelerometer 

IEEE MEMS 2000, Jan 23-27 2000 Miyazaki Japan

Accelerometer is the basic Inertial Measurement Unit (IMU) device. The main goal of this sensor is to be able to measure the lateral acceleration. The CMOS-MEMS accelerometer is integrated into a conventional CMOS chip. Such system could be as low cost and reliable as the silicon chips.

 

This photo shows the second generation CMOS-MEMS accelerometer fabricated at CMU. The size of device is about 320um by 420um and it weighs only about 0.4ug ! This lateral accelerometer consists of proof-mass (middle) and serpentine springs at the two ends of the proof-mass. The latticed structures are the release holes to make sure the silicon underneath can be etched away. The whole device is anchored on the substrate. The electronics are integrated on the same substrate (not shown in this picture).
This photo shows the device under test. The accelerometer test board is mounted on a vibration table to calibrate its performance.  
The spectrum of the output from the accelerometer. The equivalent noise floor is 1mG/sqrt(Hz).
This picture illustrates assemble of this accelerometer.
still under construction
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The goal of this project is to make an integrated IMU system which includes accelerometer and gyroscope and has six degree-of-freedom sensing ability.  

 

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