Characterization and optimization of the organic electrochemical transistors for biological applications

Abstract

In this work organic electrochemical transistors (OECTs) in combination with inkjet printed poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated for the purpose of biological applications. The use of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as the active layer for organic electrochemical transistors (OECTs) has gained attraction in the field of biosensing because of its beneficial properties such as high conductivity, ease of fabrication, flexibility and stability at different levels of pH. However, limitations in stability over time and low frequency cut-offs could constrain the use for sensors. In this thesis, the preparation protocols for PEDOT:PSS OECTs were investigated and compared. The stability over time was investigated and experiments were carried out to assess how the thickness of the active layer affects the frequency cut-off and the transconductance (gm) of the sensor. Experiments with Cardiac Myocytes (HL1 cells) were performed to test the devices for their electrophysiological performance.

The fabricated sensors show, depending on the fabrication parameters, excellent gm values, while the measurements and -conditions strongly influence their stability over time. The insight gained from this project is greatly enhancing the knowledge of sensor fabrication and possible applications. However improvements for the long-term stability could be necessary so that further research has to be performed in this direction.