NIR-II Light-Activated Neurostimulation Enabled by Broad-Angle Light Concentrating

Precise, wireless control of battery-free implantable neurostimulators using light offers a promising avenue for treating neurological disorders, while the strong tissue absorption, scattering, and alignment uncertainties under in vivo conditions limit their reliability. Here, we harness the deep tissue penetration of second near-infrared (NIR-II, 1000-1400 nm) light to develop a NIR-II light-activated neurostimulation based on integrated photothermal and pyroelectric energy conversion with a special broad-angle lens-free light concentrator. The flower-inspired light concentrator enables efficient harvesting of scattered, non-collimated light deep within tissues and eliminates the angular dependence common to existing systems. The synergistic photothermal-pyroelectric conversion mechanism enables effective utilization of diffuse 1064 nm NIR-II laser illumination and facilitates substantial device miniaturization, resulting in an exceptionally high voltage-to-volume output ratio. In vitro and in vivo evaluations confirm its biocompatibility and ability to precisely activate the nerve and modulate limb motion in frogs. Furthermore, in vivo studies in rabbits demonstrate that the device, following subcutaneous implantation, enables immediate light-triggered electrical stimulation of the sciatic nerve through pulsed 1064 nm NIR-II laser irradiation. This work establishes a robust and minimally invasive paradigm for light-controlled neuromodulation, offering broad applicability in next-generation bioelectronic systems.