An innovative tri-axes micro-power receiver for inductively wireless power transmission

Abstract

An innovative tri-axes micro-power receiver is proposed and studied for wireless magnetic energy transmission. The tri-axes micro-power receiver mainly consists of two sets of three-dimensional micro-solenoids and one set of planar micro-coils in which individual iron core is all embedded. The three sets of micro-coils/micro-solenoids are designed to be orthogonal to each other. Therefore, no matter which direction the input magnetic flux is present along, the supplied magnetic energy can be harvested and transformed into electric power by the proposed micro-power receiver in wireless sense. Not only the dead zone of receiving power is greatly reduced, but also transformation efficacy of magnetic energy into electric power can be much enhanced. By Governing Equations Analysis (GEA), based on Biot-Savart law and Faraday's law, the mathematical description upon power transmission from transmitter to receiver is established. The estimation error on power transmission by commercial software, Ansoft Maxwell, based on finite element method, is revealed, in comparison to GEA method. Moreover, the design parameters of tri-axes micro-receiver are examined and verified for follow-up fabrication and experiments. Particularly for the micro electro mechanical systems process, the isotropic etching technique is employed to micro-machine the inverse-trapezoid fillister for solenoid at receiver, so that the copper wire can be successfully electroplated. Therefore, the adhesion between micro-coils and fillister is hence much enhanced as well.