flexLiTE: flexible micro-LED integrated optoelectrodes for long-term chronic deep-brain studies

Understanding complex neuronal circuitry and its functions of a living organism requires a specialized tool which is capable of recording a large ensemble of neuronal signals at single cell resolution and modulating neuronal activities selectively in the target region of brains with high spatiotemporal resolution, while sustaining long-term chronic operation without significant tissue degeneration or device shifts. We hereby present an ultra-flexible, minimally-invasive, Michigan-type neural probe for chronic opto-electrophysiology studies: flexLiTE (flexible micro-LED integrated optoelectrodes). flexLiTE incorporates monolithically integrated, soma-sized inorganic micro-LEDs (12 individually operated) and 32 recording electrodes. Both stimulation and recording modalities were achieved by stacking two modules on a flexible substrate: one with micro-LEDs for neuromodulation and the other with recording sites, resulting in a 115 μm-wide,12 μm-thick, 10 mm-long optoelectrode. From prototype devices, we demonstrated the reliable operation of flexLiTEs for recording and modulation of hippocampal neurons in a freely moving mice for over ∼8 month.