Sensing Below the 1G Acceleration Barrier

Tokyo Tech develops a high-sensitivity micro-accelerometer on a chip.

Accelerometers are essential instruments for many industrial and scientific applications. In aerospace alone, accelerometers are used for aircraft navigation systems, missile guidance, and for flight stabilization of unmanned aerial vehicles. The development of microelectromechanical systems has allowed these sensors to be fabricated on an extremely small scale, for use in smartphones and electronic game controllers to sense user movements. The continuing development of this technology has led to demand for increased measurement sensitivity, particularly for low acceleration.

Acceleration measurement on the micron scale

A team at Tokyo Institute of Technology has now developed a new small and sensitive microelectromechanical accelerometer. Using a multilayer metal technology, the new accelerometer was integrated with commonly used integrated circuits.

Figure.
Illustration of the microelectromechanical accelerometer on a complementary-symmetry metal–oxide–semiconductor large-scale integrated circuit (CMOS-LSI)

Accelerometer design

The team from Tokyo Tech developed a single-axis accelerometer. This measures changes in the position of a specially designed gold "proof mass," which dangles above a fixed electrode held by micro-springs. Motion in the z-axis direction makes the proof mass move, which causes changes in the fixed electrode (this forms part of the integrated circuit used), thereby giving a precise measurement of the acceleration experienced by the device.

Small-scale accelerometer, large-scale production

The excellent sensitivity of the microelectromechanical accelerometer to very low acceleration, and its integration with standard electronic circuits, show good potential for rapid integration with existing hardware. The team demonstrates that mass production of these tiny but highly sensitive integrated devices is entirely feasible.

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