Design and fabrication of all-polymer transducers with different functional features for basic neuroscience and neuroprosthetics

Neural prostheses aim at recording or altering nervous system activity to partly restore motor, sensory or cognitive modalities that have been lost because of disease or trauma. Where appropriate, microelectrode arrays (MEAs) facilitate high-density recordings and local stimulation of neural activity in the brain. Their body integration, functionality and long-term stability may be improved by resorting to new, more tissue-like materials and conductors with low interface impedance and large charge transfer capacity. Recently, we presented an in vitro prototype of a highly flexible polymeric MEA made of a polydimethylsiloxane (PDMS) scaffold with microchannel tracks and electrodes which were coated with films of organic conductors or filled with a graphite-PDMS composite paste [1]. Here, we present an exemplary design concept for in vivo probes with carbon-PDMS conductors based on the same replica-molding technology. They were fabricated from laser-printed templates and feature a particular squeeze-clamping interconnection scheme based on rubber-like contact pads. This “soft contact” strategy alleviates stress-related twist and break found in classically bonded pads in ribbon cable-type wiring to external electronics.