Fig. 5.

Dopamine detection with the needle-type OECT. a Electrochemical response of the PEDOT:PSS gate electrode to DA. Scan rate 100 mV s⁻¹. b Transfer curves recorded in presence of increasing amounts of DA. V_d = − 200 mV, scan rate 10 mV s⁻¹. c Threshold voltage response to the concentration (inset) and logarithm of DA concentration in the nM range. Standard deviations are given as error bars. dI_d vs time curve recorded during increasing additions of DA in the range from 1 to 160 pM (V_g = − 900 mV; V_d = − 300 mV). Calibration curves obtained e from 1 to 160 pM and f from 2 to 700 nM DA