Final Report Summary - FUNMANIA (Functional nano Materials for Neuronal Interfacing Applications)
In this project several efficient nanoscale optoelectronic system were studies and optimized for neuronal stimulation, focusing on high resolution retinal stimulation for visual restoration. Ultimately, a semiconducting organic electrolytic photo capacitor was developed and is presently tested in vivo to evaluate its suitability for artificial retina applications, the stated goal of the Funmania project. The devices we developed comprise a thin (80 nm) trilayer of metal and p–n semi conducting organic nanocrystals. When illuminated in physiological solution, these metal–semiconductor devices charge up, transducing light pulses into localized displacement currents that are strong enough to electrically stimulate neurons with safe light intensities. The devices are freestanding, requiring no wiring or external bias, and are stable in physiological conditions. The semiconductor layers are made using ubiquitous and nontoxic commercial pigments via simple and scalable deposition techniques. We also studied how, in physiological media, photovoltage and charging behavior depend on device geometry. Finally, the efficacy of these devices was demonstrated by achieving direct optoelectronic stimulation of lightin sensitive retinas, proving the potential of this device platform for retinal implant technologies and for stimulation of electrogenic tissues in general. These results substantiate the conclusion that these devices are the first non Si optoelectronic platform capable of sufficiently large photovoltages and displacement currents to enable true capacitive stimulation of excitable cells.