Proceedings of 2018 ASEE Northeast Section Conference

Wireless System for FM Transmission of MEMS Capacitive Vibration Sensor Data
Shaun Sylvester, Mustafa Guvench
Abstract

Microelectromechanical systems or MEMS is a new field of microfabrication with exciting possibilities in aerospace, industrial and biomedical fields.  These tiny devices are robust, non-intrusive and inexpensive.  As the name implies these devices have mechanical and electrical parts on the micro-meter scale.  MEMS devices take many forms including vibration sensors, chemical sensors, optical relays and resonators. 

For my project I built a surface mount vibration sensor that wirelessly transmits data about the forces applied to a MEMS device integrated with it.  The sensor can be attached to a mechanical system or biological system to provide valuable information about the system’s sensitivity to vibration and the accelerations it is subjected to.

My project used a MEMS capacitive vibration sensor developed by Professor Mustafa Guvench at the University of Southern Maine.  The MEMS functions as a variable capacitor on the pico-Farad scale.  When the MEMS is subjected to vibrations it causes the capacitance of the device to change due to the displacement of its microscale interdigitated fingers.    

The capacitance of the MEMS device is incorporated into the resonant tank of a Colpitts oscillator. Changes in the capacitance of the MEMS cause the frequency of the oscillator to change, producing a frequency modulated (FM) signal.  The FM signal is transmitted by an inductor and received by a Noolectric NESDR Smart software defined radio (SDR).  Software developed by Kyle Brown at the University of Southern Maine is used to demodulate and calculate the forces acting on the MEMS device in real time. 

The MEMS, oscillator and transmitter were packaged together to produce an easy to use wireless vibration sensor that is small enough to attach to a mechanical system or organism.  Future work on the device will concentrate on decreasing its size.  Decreasing the size of the package will allow it to be attached to smaller mechanical systems and animals without disrupting their normal behavior. 

Last modified: 2018-04-27
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