Silicon-Embedded Receiving Coil for High-Efficiency Wireless Power Transfer to Implantable Biomedical ICs

In this letter, a silicon-embedded receiving coil is designed and fabricated for high-efficiency wireless power transfer to implantable biomedical ICs. The 4.5 mm × 4.5 mm embedded receiving coil achieved a large inductance of 4 μH and a high peak quality factor of 20 at 2.8 MHz. Measurement results of an inductive power link using the embedded receiving coil and a conventional printed-circuit-board transmitting coil (2 cm × 2 cm) demonstrated peak voltage gains of 0.84 and 0.24 and peak efficiency values of 30% and 4.3% for separation distances of 5 and 12 mm, respectively. This is the best reported wireless power transmission efficiency for separation distance similar to the implant chip size.