Stackable Wireless Controller of Single-Sided µLed Arrays For Optogenetics in Freely Behaving Animals

This study reports on a fully autonomous system comprising a wireless headstage and an array of micro light-emitting diodes (µLED) integrated in a flexible neural probe for optogenetic experiments. The 49 µLEDs (50×50 µm ² ) are arranged at a minimal pitch of only 100 µm. The µLED-based neural probes are realized using a novel, single-sided fabrication process on the expitaxial sapphire substrate that avoids the delicate µLED transfer using wafer bonding and laser lift-off. The absolute optical power per µLED is 1.1 mW at 465 nm peak wavelength, resulting in an emittance of more than 500 mW/mm ² at the µLED surface. The µLEDs of the optical neural probes are powered and controlled by a compact (diameter 18.7 mm, height 19.8 mm), light-weight (6.44 g), modular headstage. It enables the simultaneous operation of multiple probes serially addressing up to two arrays with each up to 16×16 µLEDs for about 2 h under continuous operation.