Flexible screen-printed coils for wireless power transfer using low-frequency magnetic fields

TitleFlexible screen-printed coils for wireless power transfer using low-frequency magnetic fields
Publication TypeJournal Article
Year of Publication2019
AuthorsSondhi, K., N. Garraud, D. Alabi, D. P. Arnold, A. Garraud, S. G. R. Avuthu, Z. H. Fan, and T. Nishida
JournalJournal of Micromechanics and Microengineering
Date PublishedJan-08-2019

We report the fabrication and testing of a multilayer flexible screen-printed coil that can be used to generate low-frequency (<1 kHz) magnetic fields for applications such as electrodynamic wireless power transmission (EWPT). Compared to traditional coil-forming methods, screen printing enables rapid fabrication of thin, light weight, conformable, and flexible structures. The flexibility is demonstrated by repeated bending of a stack of up to three layers for a curvature (inverse bending radius) of 53.2 . We also demonstrate wireless power transmission of 1 mW of power at a distance of 4 cm between the flexible receiver and transmitter. The effect of the flexibility is observed through a 32% power increase when the receiver is bent concavely and a 20% output power decrease when the stack is bent convexly. It is also seen that the insertion of a 0.2 mm-thick soft-magnetic material sheet increased the magnetic field by 41% from its original value. Mechanical cycling was also performed for the stack. After 10 000 bending cycles, a 16.4% increase in the coil resistance was measured for a 0.33 Hz frequency and 78% increase for a 1 Hz cycling frequency, respectively. Screen printed 3D flexible transmitter coils can enable the incorporation of EWPT for wireless charging in applications such as healthcare and consumer-based electronics.

Short TitleJ. Micromech. Microeng.