Wireless multichannel optogenetic stimulators enabled by narrow bandwidth resonant tank circuits

Optogenetic neuromodulation is a powerful technique used to study cells that form part of neuronalcircuits. Light stimulation of neurons has led to a deeper understanding of autism, schizophrenia anddepression. However, researchers are often limited to tethered systems involving percutaneous plugs,hence, wireless power transmission to an implantable device is desirable. This work details the design,fabrication and testing of multichannel wirelessly powered optogenetic devices. By employing severalcarefully tuned resonant tank circuits, this work demonstrates the ability to address a scalable num-ber of light sources on a single device. Single channel, dual channel and 16 channel devices werefabricated, achieving light output readings of up to 15mW at 473nm, suitable for activating channel-rhodopsin. Wireless power transmission was characterized in air and porcine tissue for implant depthsup to 30mm, making device implantation feasible. The device was successful in activating endogenous(in retinal ganglion cells) and exogenously transfected channelrhodopsin in human embryonic kidneycells, providing biological validation. The significance of this approach is the removal of power-hungryand area-consuming electronics from the implant, while the ability to address and modulate individuallight sources is maintained by shifting this complexity to the external wireless power transmitter.