Extracellular voltage noise probes the interfaces between retina and silicon chip

Neuroprosthetic devices rely on a tight contact between electrodes and neurons in the interfaced tissue. A simple method to probe the contact properties in a non-invasive way would be highly attractive. Here we show for retinal tissue that crucial electrical propertiesof the interface can be extracted from the voltage noise that is recorded with an array of capacitive sensors. The monitoring of the interface properties, which are either interpreted as variable local conductivities or as a cleft of varying distance, allows assessment of the long-term efficiency of neuroprosthetic devices.