Multisite microLED optrode array for neural interfacing

TLDR

The authors present an electrically addressable optrode array that delivers light to 181 brain sites to optogenetically excite thousands of neurons in vivo, aiming to enable behavioral studies in large mammals, and they explore future designs via optical and thermal modeling benchmarked against the current device. The device consists of a glass microneedle array integrated with 181 microLEDs (80 × 80 µm²) fabricated on a 150‑µm GaN‑on‑sapphire wafer, coupled to a 150‑µm thick backplane, with a pinhole layer to reduce stray light, delivering light to 100 needle tips and 81 interstitial surface sites for two‑level optogenetic excitation in vivo. The device achieves peak irradiances exceeding 80 mW/mm² per needle site while maintaining acceptable thermal performance.

Abstract

We present an electrically addressable optrode array capable of delivering light to 181 sites in the brain, each providing sufficient light to optogenetically excite thousands of neurons <italic>in vivo</italic>, developed with the aim to allow behavioral studies in large mammals. The device is a glass microneedle array directly integrated with a custom fabricated microLED device, which delivers light to 100 needle tips and 81 interstitial surface sites, giving two-level optogenetic excitation of neurons <italic>in vivo</italic>. Light delivery and thermal properties are evaluated, with the device capable of peak irradiances &gt;80 mW / mm² per needle site. The device consists of an array of 181 80 μm × 80 μm² microLEDs, fabricated on a 150-μm-thick GaN-on-sapphire wafer, coupled to a glass needle array on a 150-μm thick backplane. A pinhole layer is patterned on the sapphire side of the microLED array to reduce stray light. Future designs are explored through optical and thermal modeling and benchmarked against the current device.