26.8 A Trimodal Wireless Implantable Neural Interface System-on-Chip

Implantable biomedical devices (IMDs) capable of injecting a designated current into target neural tissue to modulate neural activity have been proven therapeutically effective. The next generation of IMDs is expected to sense changes in the evoked neural activities, allowing recorded data to be used as feedback mechanism to adjust stimulation parameters/patterns, making these systems even more effective while reducing power consumption [1]. Recently, optogenetic neuromodulation with distinct advantages of cell-type specificity, high temporal precision, and rapid reversibility has been added to researchers' arsenal and resulted in the development of IMDs with optical stimulation capability [2], [3]. An IMD with both optical and electrical stimulation capabilities, plus neural recording, is expected to offer ultimate flexibility to users for executing advanced neuromodulation paradigms that are not possible with today's technology. This may also give users the ability to lower optical stimulation threshold by priming the neural tissue with sub-threshold current. In [4], al 13 functions are presented; however, optical stimulation is not integrated, channel counts are limited, and the power source is a battery. A key feature that brings an IMD closer to clinical use is wireless power delivery and data communication. Here we present a fully integrated, wireless, and high-channel-count trimodal neural interface SoC.