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SUMMARY:Design\, modelling\, and fabrication of a resonant micromachined m
 agnetic field sensor - Dr. Behraad Bahreyni\, Nano-center\, Department of 
 Engineering
DTSTART:20061108T140000Z
DTEND:20061108T150000Z
UID:TALK5749@talks.cam.ac.uk
CONTACT:Dr. Richard\, Yong Qing Fu
DESCRIPTION:In this talk\, a novel micromachined magnetic field sensor was
  designed and fabricated. The sensor operation is based on fundamental ele
 ctromagnetic laws to produce a mechanical stress proportional to the stren
 gth of the present magnetic field. The exerted stress modifies the resonan
 t frequency of an electrostatic resonator\, and hence\, the sensor output 
 is a frequency shift proportional to the magnitude and direction of the pr
 esent field. Operation of the sensor involves interaction of multiple phys
 ical domains including: magnetostatic\, electrostatic\, static\, dynamic\,
  and electro-thermo-mechanical. A comprehensive model of the sensor behavi
 or is derived and verified by finite element simulations and experiments. 
 The sensor was fabricated in a standard bulk micromachining process withou
 t the need for any additional processing steps. Custom signal processing e
 lectronics were designed and used to analyze the sensor data. A novel conf
 iguration is proposed for employing the resonator in an oscillator loop as
  well as the circuitry for measuring the frequency shifts. Experimental re
 sults for the measurements of magnetic fields and performance of the elect
 ronic circuitry are also presented. The noise behavior of the sensor is al
 so investigated and the minimum detectable signal for each device is found
 . The measured resolution of the fabricated sensors in self-oscillating co
 nfiguration using off-the shelf discrete electronics is about 77uT. A line
 ar response to a wide range of magnetic fields makes this design suitable 
 for applications where large fields need to be measured with high resoluti
 on
LOCATION:CAPE building\, seminar room 21-23. 9 JJ Thomson Ave. CB3 0FA
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