Analytical evaluation of magnetic field by planar micro-electromagnet spirals for MEMS applications

Abstract

A computationally efficient analytical technique is adopted and modified to evaluate the magnetic and magnetostatic force fields produced by MEMS-scale planar electromagnetic spirals. The predicted magnetic field distribution is validated experimentally at a scaled-up geometry. Except the regions very close to the spiral, the predicted field is found to match well with the measured values. The force field established by a standard configuration of a spiral-shaped microelectromagnet, which is suitable for MEMS-based actuators and sensors, is investigated. The analysis shows that the zones of high magnetic field, its gradient and force magnitude occur right above the center of the spiral, while the regions of high force fields exist along the diagonals of the spiral. Parametric investigation is performed to evaluate the optimum number of turns in the spiral, which indicates that the inner loops of the spiral influences the magnetic and force fields more pronouncedly than the outer loops. The method offers an easy tool for comparing different design alternatives of spiral electromagnets for use in magnetic MEMS devices.