Fabrication and characterization of micro electromagnetic linear actuators

Abstract

Abstract This paper on the reports design, fabrication and position monitoring of a micro electromagnetic linear actuator. The actuator consists of stator, slider, guide, sensors and affiliated jigs. Actuation is achieved through ampere force between two phase micro-coils (copper) on the stator and permanent magnets (thick NdFeB film) on the slider. During the slider’s movement in the guide slot, tunnelling magneto-resistance (TMR) sensors are utilized to sense the magnetic field to realize position monitoring. TMR is chosen because it owns advantages of small size, large sensitivity and easy integration with micro devices. Purpose of this research is to report the micro fabrication of thick magnet films and testify the possibility of using TMR as position monitoring sensors. Actuators are fabricated by micro-electro-mechanical system process (stator and guide) and precise machining (slider and jigs). Surface magnetic field generated by the slider, driving characteristics of the actuator as well as the position monitoring capabilities of TMR elements are simulated and experimented, respectively. The slider attains 60 mm s−1 speed by sinusoidal input signal at 300 Hz frequency and 0.2 A current magnitude. Actuation bandwidth is between 300 Hz and 500 Hz at open loop condition. The maximum position monitoring error in present work is 2.2% with 101 μm value for 4.5 mm stroke.