Wireless, Battery-Free Implant for Motor Cortex Chronic Stimulation

This work presents a safety assessment of the e-dura substitute concept, where a wireless, battery-free implant is integrated onto a biocompatible, FDA-approved (U.S. Food and Drug Administration) collagen dura substitute for delivering cortical stimulation without contacting the brain surface. The device operates by responding to On-Off-Keying (OOK) modulation of a wireless signal, and it generates voltage pulses, while relaying an optical signal as feedback for post-surgery tracking of device operation. The implant's long-term performance was assessed by submerging the device in saline at human body temperature for eight weeks, and the results show that the output voltage remained at 76.5% of the initial value before the test when using a biocompatible silicone adhesive as the outer encapsulation. Continuous stimulation was delivered for 5 hours in two rats to study the impact of prolonged exposure to wireless stimulation on tissue integrity, and histological analysis was performed to verify tissue integrity post-stimulation. The results reveal no remarkable changes on high and low magnification when comparing the stimulated and non-stimulated hemispheres in two rodents, further confirming the safety of the e-dura method for chronic electrical stimulation treatment.