Stretchable multichannel antennas in soft wireless optoelectronic implants for optogenetics
Significance Soft, multichannel antennas enable wireless, battery free operation of fully implantable optoelectronic systems designed for use in studies of brain function. These systems support independent, remote control of multiple light emitting diodes that inject into targeted regions of the deep brain, where they separately stimulate activity in genetically and spatially discrete neural circuits, via the use of the techniques of optogenetics. These capabilities represent significant advancements over alternative technology approaches for this important branch of neuroscience research. In vivo studies using optimized systems demonstrate wireless control of two different brain regions and distinct activation of subpopulations of neurons using separately activated light sources associated with these subdermal devices. Optogenetic methods to modulate cells and signaling pathways via targeted expression and activation of light sensitive proteins have greatly accelerated the process of mapping complex neural circuits and defining their roles in physiological and pathological contexts. Recently demonstrated technologies based on injectable, microscale inorganic light emitting diodes (m ILEDs) with wireless control and power delivery strategies offer important functionality in such experiments, by eliminating the external tethers associated with traditional fiber optic approaches. Existing wireless m ILED embodiments allow, however, illumination only at a single targeted region of the brain with a single optical wavelength and over spatial ranges of operation that are constrained by the radio frequency power transmission hardware. Here we report stretchable, multiresonance antennas and battery free schemes for multichannel wireless operation of independently addressable, multicolor m ILEDs with fully implantable, miniaturized platforms. This advance, as demonstrated through in vitro and in vivo studies using thin, mechanically soft systems that separately control as many as three different m ILEDs, relies on specially designed stretchable antennas in which parallel capacitive coupling circuits yield several independent, well separated operating frequencies, as verified through experimental and modeling results. When used in combination with active motion tracking antenna arrays, these devices enable multichannel optogenetic research on complex behavioral responses in groups of animals over large areas at low levels of radio frequency power <1 W) Studies of the regions of the brain that are involved in sleep arousal (locus coeruleus) and preference/aversion (nucleus accumbens) demonstrate the unique capabilities of these technologies.
Proceedings of the National Academy of Sciences