Single-channel opto-neurostimulators: a review

Optogenetics is a revolutionary neuromodulation technique to excite or inhibit the activity of the targeted neurons that express light-sensitive opsin proteins. Opto-neurostimulators as neural interface devices are significantly important for optogenetic applications in neuroscience and future clinical research. To date, a wide variety of optical stimulators have been developed and could be classified into two broad categories: single-channel and multi-channel stimulators. Although multi-channel opto-neurostimulators allow spatially controlled optical stimulation of cells, they require complicated fabrication procedures and might require specialized coupling strategies at the distal end of the optical source. As an alternative, single-channel opto-neurostimulators are gradually being prevalent in many applications for their simplicity, ease of use, and low cost. We have reviewed a variety of single-channel optogenetic neural stimulators that were developed in recent years, based on different light sources, material selection, and tethered or wireless systems. This paper accumulates and summarizes these single-channel opto-neurostimulators to provide a comprehensive outlook for the trend of this field.