Highly sensitive dopamine biosensors based on organic electrochemical transistors.

Organic electrochemical transistors (OECTs) based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) with different gate electrodes, including graphite, Au and Pt electrode, etc., have been used as dopamine sensor for the first time. The sensitivity of the OECT to dopamine depends on its gate electrode and operation voltage. We find that the device with a Pt gate electrode characterized at the gate voltage of 0.6 V shows the highest sensitivity. The detection limit of the device to dopamine is lower than 5 nM, which is one order of magnitude better than a conventional electrochemical measurement with the same Pt electrode. It is expected that OECT is a good candidate for low cost and highly sensitive biosensor for the detection of dopamine.