Organic electrochemical transistor (OECT)

An organic electrochemical transistor uses a conducting-polymer channel (typically PEDOT:PSS) gated by ions from the surrounding electrolyte: a small gate voltage drives ions into or out of the polymer bulk, de-doping it and modulating a large source-drain current. Because gating exploits the material's volumetric capacitance, OECTs achieve very high transconductance at low voltage and amplify the neural signal locally, at the recording site, before it travels down a lead.

In-situ amplification improves SNR and eases the wiring and multiplexing burden for high-density arrays, and OECT arrays have recorded ECoG and even single units in vivo. Trade-offs: ionic gating makes them intrinsically slower than silicon transistors (though fast enough for neural bands), and, like all PEDOT devices, their chronic stability is bounded by polymer degradation and the same delamination concerns as passive coatings.