A Wireless Battery-Free Implant With Optical Telemetry for In Vivo Cortical Stimulation

We present a 100
$\mu \rm {m}$
-thick, wireless, and battery-free implant for brain stimulation through a U.S. Food and Drug Administration-approved collagen dura substitute without contact with the brain's surface, while providing visible-light spectrum telemetry to track the onset of stimulation. The device is fabricated on a 16
$\times \;$
6.67 mm
$^{2}$
biocompatible parylene/PDMS substrate and is encapsulated with a 2
$\mu \rm {m}$
-thick transparent parylene layer that enables the relay of the LED brightness. The
in vivo
rodent testing confirmed the implant's ability to trigger motor response while generating observable brightness through the skin. The results reveal the prospect of wireless stimulation with enhanced safety by eliminating contact between the implant and the brain, with optical telemetry for facilitated tracking.