Analysis of micropatterned wireless resonant heaters for wireless-control of MEMS thermal actuators

Abstract

This paper reports a study on wireless radiofrequency (RF) power transfer to and heat generation in micropatterned coils for wireless control of thermally-driven microdevices. Inductor-capacitor circuits with the planar spiral coils act as RF receivers as well as frequency-sensitive wireless heaters that selectively produce heat when resonated with external RF magnetic fields. Electrical and thermal characterizations are performed using two sets of microfabricated circuits with varying numbers of turns and fill ratios defined in the spiral coils. The measurements in electrical parameters of the circuits, coupling coefficient, power transfer efficiency, and heat generation have been evaluated and parameters show good consistency between them. These tests reveal maximum power transfer efficiency and steady-state temperature of ~35 and 99 C, respectively, for the coil with a fill ratio of 0.55. The reported results will serve as a basis for the design of the wireless heater, which provide a promising path to radio-control of thermoresponsive actuators such as shape-memory alloys and hydrogels