An Implantable Ciliary Muscle LFP Recording and Transmitting System

In this work, we present a sclera-attachable eye implant to measure ciliary muscle local field potentials (LFPs) as a demonstrator for a preclinical study. The recorded values can be plotted and filtered in real-time. It records with a single differential channel with sampling rates of up to 250 Hz and offers a programmable gain amplifier. We show the measurement quality with in vivo measurements. The system is powered by a CR1025 coin cell battery and different measures are presented to improve measurement quality and run-time. The impact of battery non-idealities is investigated. The implant measures 18x12 mm with an actual area of 168 mm² and consumes up to 375 μA in ACTIVE mode with a total measurement run-time of up to 80 hours. The whole system, including the battery, is implantable into the orbital cavity and a standby time of 6 months is obtained.