An omnidirectional WPT platform for distributed fully implanted neural recording systems.

Recent progress on human brain science requires developing advanced neural recording system to capture the activity of large neural populations accurately, across a large area of the brain, and over extended periods. Recently proposed distributed neural recording systems with numerous implanted devices require reliably energizing them wirelessly. Random distribution of these mm-sized implants and brain motion place them at different positions and orientations with respect to the power transmitter. Therefore, traditional wireless power transfer techniques fall short of reaching sufficient power for all implants simultaneously, rendering some implants nonfunctional. In this paper, a three-layer power transmitting array with three-phase coil excitation current is introduced, which is capable of producing omnidirectional and homogeneous magnetic field across the volume where the Rx coils are located. The individual coil dimensions in the array is optimized to improve the worst-case scenario in terms of homogeneity, which is further verified by the measurements using a scaled-up prototype system. The measurement results show that the minimum received voltages is improved from 0.34 V for 10-mm side-length hexagonal transmitting coil array to 0.83 V for the optimal case, i.e., 35 mm side-length hexagonal transmitting coil array. [ABSTRACT FROM AUTHOR]