Stacked spirals for use in biomedical implants

A new type of wireless transmission coil is proposed for biomedical implants. By stacking several spirals above one another, the space required for an implantable coil is miniaturised, the self-resonant frequency (SRF) of the spiral is reduced, as is the required power transmission frequency for the implanted device. A four-layer 15 mm × 15 mm spiral coil of seven turns was simulated in CST Microwave Studio (TM), and constructed and successfully tested in hardware.