Fig. 3. Ionic-to-electronic amplification mechanism.

To operate the organic electrochemical transistor complementary amplifier with high sensitivity, the input voltage is biased at V_I = V_M, while the output voltage is continuously measured. Light-blue characteristic: at V_I = V_M the output V_O = V_O’ and the ion concentration is c₀. A small variation of the ion concentration results in a shift of the electrical characteristic (from light-blue to dark-blue) and this, in turn, in a large variation of the output voltage from V_O’ to V_O”.