Adv. Mater. http://doi.org/r6k (2014)

In view of their high sensitivity to gate modulation, organic electrochemical transistors based on a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) conducting channel have been proposed as probes that can be used in vivo to record signals from electrogenic cells. Alessandra Campana and colleagues have now developed a protocol to fabricate these devices on resorbable substrates. They used shadow-mask deposition to form the metal contacts and dry etching of the thin PEDOT:PSS layer spin-coated on poly(L-lactide-co-glycolide) — a biocompatible and biodegradable copolymer used for temporary implants — to realize transistors that are able to detect voltage signals with amplitudes and frequencies comparable to those of extracellular action potentials. The probes were tested by attaching to human skin and taking electrocardiographic measurements; they recorded cardiac waveforms with good fidelity. The researchers suggest that high-performing organic electronics based on materials that are mechanically compliant with human tissues, biocompatible and fully resorbable will be a key technology for the realization of implantable devices with minimal invasiveness.