In magnetic resonance imaging (MRI), wearablewireless receive coil arrays are a key technology goal. An MRIcompatible wireless power transfer (WPT) system will be neededto realize this technology. An MRI WPT system must withstandthe extreme electromagnetic environment of the scanner and can-not degrade MRI image quality. Here, a WPT system is developedfor operation in MRI scanners using new microelectromechanicalRF (RF MEMs) switch technology. The WPT system includesa class-E power amplifier, RF MEMs automated impedancematching, a primary coil array employing RF MEMs powersteering, and a flexible secondary coil with class-E rectification.To adapt WPT technology to MRI, techniques are developed foroperation at high magnetic field, and to mitigate the RF interac-tions between the scanner and WPT system. A major challengewas the identification and suppression of noise and harmonicinterference, by gating, filtering, and rectifier topologies. Thesystem can achieve 63% efficiency while exceeding 13-W deliveryover a coil distance of 3.5 cm. For continuous WPT beyond 5 W,added filters and full-wave class-E rectification lower harmonicgeneration at some cost to efficiency, while image signal-to-noiseratio (SNR) reaches about 32% of the ideal. RF-gated WPT,which interrupts power transfer in the MRI signal acquisitioninterval, achieves SNR performance to within 1 dB of the ideal.With further refinement, the inclusion of WPT technology inMRI scanners appears completely feasible.