Stretchable multichannel antennas in soft wireless optoelectronic implants for optogenetics

Abstract

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 (mu-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 mu-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 mu-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 mu-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.