Optically-interrogated zero-power MEMS magnetometer

Daniel J. Vasquez

doi:10.1109/JMEMS.2007.892795

2007-04-01

PRE

Daniel J. Vasquez *

Jack W. Judy

DOI：10.1109/JMEMS.2007.892795

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摘要

En 中文

A magnetic-field-sensing system that consists of a miniature zero-power magnetometer, an integrated micromachined corner-cube reflector (CCR), a commercially available diode laser, and a photodetector array, has been designed, fabricated, assembled, and tested. The zero-power-magnetometer design is based on a ferromagnetic MEMS magnetometer, which consists of a permanent magnet that is torsionally suspended to allow rotation about a single axis. A single mirror of the CCR is attached to the magnetometer torsion beam. When the magnet rotates in response to a change in magnetic field, the torsion beam will twist and cause the mirror to become misaligned. The non-ideality of the CCR can be interrogated with a laser and a photosensor array can be used to measure the reflected signal. This method of magnetic sensing completely eliminates sensor-node power consumed at the remote location. The sensor node developed for this paper occupies a volume of only 1.5 mm(3) and can detect a magnetic field between 820 A/m to 6 kA/m with an uncertainty of 90 A/m at a 1-m optical-interrogation range. The primary application of this technology is in wireless sensing systems that must operate continuously without providing or maintaining the sensor-node energy (e.g., replacing batteries or scavenging energy) or in extremely harsh environments where power supplies and integrated circuits (IC) are not an option.

Keyword:

ferromagnetic materials

magnets

magnetometers

microelectromechanical devices

microsensors

multisensor systems

optical device fabrication

optical diffraction