title: Wireless displacement sensing of micromachined spiral-coil actuator using resonant frequency tracking.
abstract: This paper reports a method that enables real-time displacement monitoring and control of micromachined resonant-type actuators using wireless radiofrequency (RF). The method is applied to an out-of-plane, spiral-coil microactuator based on shape-memory-alloy (SMA). The SMA spiral coil forms an inductor-capacitor resonant circuit that is excited using external RF magnetic fields to thermally actuate the coil. The actuation causes a shift in the circuit's resonance as the coil is displaced vertically, which is wirelessly monitored through an external antenna to track the displacements. Controlled actuation and displacement monitoring using the developed method is demonstrated with the microfabricated device. The device exhibits a frequency sensitivity to displacement of 10 kHz/µm or more for a full out-of-plane travel range of 466 µm and an average actuation velocity of up to 155 µm/s. The method described permits the actuator to have a self-sensing function that is passively operated, thereby eliminating the need for separate sensors and batteries on the device, thus realizing precise control while attaining a high level of miniaturization in the device.
authors.affiliation: Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Skudai, Johor 81310, Malaysia. sultan_ali@fke.utm.my.
authors.forename: Mohamed Sultan Mohamed
authors.initials: MS
authors.lastname: Ali
authors.affiliation: Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Skudai, Johor 81310, Malaysia. ahaalaa2@live.utm.my.
authors.forename: Alaa
authors.initials: A
authors.lastname: AbuZaiter
authors.affiliation: Department of Electrical and Computer Engineering, The University of British Columbia, 2332 Main Mall, Vancouver, BC V6T 1Z4, Canada. colin.schlosser@gmail.com.
authors.forename: Colin
authors.initials: C
authors.lastname: Schlosser
authors.affiliation: Department of Electrical and Computer Engineering, The University of British Columbia, 2332 Main Mall, Vancouver, BC V6T 1Z4, Canada. bbycraft@gmail.com.
authors.forename: Brad
authors.initials: B
authors.lastname: Bycraft
authors.affiliation: Department of Electrical and Computer Engineering, The University of British Columbia, 2332 Main Mall, Vancouver, BC V6T 1Z4, Canada. takahata@ece.ubc.ca.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Takahata
mesh_terms: D004867:Equipment Design / Q000295:instrumentation; D060526:Magnetic Fields; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D055616:Microtechnology / Q000295:instrumentation; D008904:Miniaturization / Q000295:instrumentation; D011846:Radio Waves; D059015:Wireless Technology / Q000295:instrumentation*