Backscattering Neural Tags for Wireless Brain-Machine Interface Systems

Brain-machine interface (BMI) technology has tremendous potential to revolutionize healthcare by greatly improving the quality of life of millions of people suffering from a wide variety of neurological conditions. Radio-frequency identification (RFID)-inspired backscattering is a promising approach for wireless powering of miniature neural sensors required in BMI interfaces. We analyze the functionality of millimeter-size loop antennas in the wireless powering of miniature cortical implants through measurements in a human head equivalent liquid phantom and in the head of a postmortem pig. For the first time, we present the design and measurement of a miniature 1 x 1 x 1 mm(3) backscattering device based on a cubic loop connected with an RFID integrated circuit (IC). Our measurement results show that this very small loop receives sufficient electromagnetic power to activate the IC when the device is implanted in a pig's head. This demonstrates the feasibility of extremely small implant antennas in challenging wireless biomedical systems.