The Application of Organic Electrochemical Transistors in Biosensors

Ion-sensitive properties of organic electrochemical transistors (OECT) based on Poly(3,4-ethylenedioxythiophene): poly(styrene sulfonic acid) (PEDOT:PSS) are systematically studied for the first time. The transfer curve (IDS ~ VG) of an OECT shifts to lower gate voltage horizontally with the increase of the concentration of cations, including H+, K+, Na+, Ca2+, and Al3+, in the electrolyte. Nernstian relationships between the shift of the gate voltage and the concentrations of the cations have been obtained. Cell-based biosensors with cancer cells cultivated on top of the OECTs have been studied. The activities of the cells under the effect of trypsin have been monitored by characterizing the OECTs. It has been found that the performance of the device is sensitive to the surface charge and the morphology of the attached cells due to the electrostatic interaction between the adherent cells and the active layer of the OECT.