Study of mm-sized Coil to Coil Backscatter Based Communication Link

Distribution of a large number of mm-sized sensing units in brain is a vision for the next generation of implantable devices for neural recording. Recorded data from the implants is conventionally transferred to a central external device and the bandwidth of the uplink channel is limited by the number of the implanted units. For the first time, we demonstrate the feasibility of local communication between mm-sized coils using backscattering technique which promises to reduce the requirement on the uplink bandwidth between the external device and the implants. To demonstrate the feasibility of the proposed link, two implanted coils located at 14 mm implantation depth are used with the distance between coils of 1.5 mm. The transmitting coil switches between two terminating impedance and the input voltage at the receiving coil is observed in the simulations with a triple-loop inductive link designed at 90 MHz. We show that the voltage difference in the received signal for two transmitting states can be resolved by demodulator of the receiving implant demonstrating the link feasibility. Several simulations show the functionality of the link under wide range of different angular and lateral misalignment.