Magnetically driven linear micro-actuators with 1 mN output force and
hundreds of microns of total travel have been realized using LIGA-like
processing techniques. These devices are driven at resonance frequenc
ies of around 350 Hz and exhibit quality factors of about 300 in air.
Exploiting wire-wound electromagnets, 300 mu m resonant displacements
have been demonstrated with drive signal currents of about 1 mA and po
wer dissipation of less than 200 mu W. In addition, the self inductanc
e of the coils in these actuators varies linearly with plunger displac
ement. The inductance changes of about 1 mu H mu m(-1) may be used for
inductive position sensing and as a measure of output force.