Wireless powering of microchip implants by a cross-slot antenna

Wireless powering enables medical implants to be miniaturized to the micron scale where devices can be injected into the body. We consider the design of the transmitter for a microchip placed 1 cm deep in tissue. We design a cross-slot antenna operating at 2.4 GHz that approximates the current distribution of the optimal transmitter. The performance of the cross-slot antenna is compared to the loop antenna in both simulation and measurement in a liquid phantom. The results show that the cross-slot antenna has better or comparable performance to the loop antenna. The cross-slot antenna can potentially generate circular polarization, which enables the link to be robust to the orientation of the receive coil.