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 mm 2 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.

Subretinal stimulators help restoring vision to blind people, suffering from degenerative eye diseases. This work aims to reduce patient's efforts to continuously tune his device, by implementing a physiological ambient illumination adaptation system. The parameters of the adaptation to changing illumination conditions are highly customizable, to best fit individual patients requirements.

Most concepts for retinal stimulation rely on rectangular waveforms, although studies suggest sinusoidal stimulation might improve visual perception. We present a novel approach for a power and area efficient generation of sinusoidal stimulation waveforms by modulation of an external reference sine wave. Modulation is performed by an attenuator based on variable CMOS pseudo-resistors. The implementation of a complete channel is presented along with two different versions of the attenuators. Both architectures are investigated in terms of signal quality, symmetry and power consumption.

Corrosion and migration effects can limit the lifetime of neural implants. Advanced and especially thicker encapsulation can increase longevity, but for retinal implants these possibilities are limited by mechanical constraints. Thorough optimization can only be achieved when the signaling schemes for exposed wires are also taken into consideration. To meet these requirements, we have implemented a current-mode communication scheme, that helps optimizing the distribution of insulation structures by combining clock and data on one wire and that reduces migration effects by reducing the wire potential to 8 mV RMS, with peak voltages below 45 mV.