Towards wireless addressable optoelectronic implants for large-scale optogenetics

This paper presents the concept and some preliminary results of a millimeter-scale wireless addressable optoelectronic implant (WAOI), a network of which can be distributed over the brain for large-scale optogenetics. The WAOI contains a wireless receiver (base), which establishes wireless power transfer and data communication with an external unit, connected to an optoelectronic shank, which integrates liquid crystal-based silicon photonic on CMOS electronics for switchable optical emission. The liquid crystal-switched waveguide can provide light switching of a single light source (e.g. laser diode), which is integrated on the base, along the shank, thus minimizing heat generation within brain parenchyma. To reduce interconnect wiring between the base and the shank, a power-line communication technique is presented for data transfer from the base to the shank. Simplified prototypes of the base and shank ASICs were designed and developed in 0.35-µm 2P4M CMOS process. The simulation results of these ASICs for addressing of 16 stimulation pixels on the shank are presented. Moreover, a macroscale example of liquid crystal-switched waveguide was fabricated and measured to demonstrate basic liquid crystal switch operation.