Organic electrochemical transistors applications in sensing and biosensing

Organic electrochemical transistors (OECTs) are promising candidates for applications in sensing and bioelectronics especially thanks to their ability to provide an interface between biology and electronic. The inherent signal amplification of OECTs has the potential to yield sensors with low detection limits and high sensitivity. We show how the device characteristics can be tailored via the appropriate choice of the device geometry and the materials used for channel, gate electrode and electrolyte. In particular we explored OECTs based on PEDOT:PSS using ionic surfactants as electrolytes (such as hexadecyl trimethyl ammonium bromide): interestingly, ionic surfactant electrolytes result in large transistor current modulation, especially beyond the critical micellar concentration in water. UV-Vis optical absorption revealed that current modulation is accompanied by an electrochemical reduction of the conducting polymer. Since cationic lipids form micelles of different shape a nd dimensions, they are ideal candidate also to investigate the mechanisms involved in OECTs and shed light onto the PEDOT:PSS doping/dedoping mechanism, one of the crucial issues in the present research in OECTs. Finally, we provide the ability of OECTs to detect and monitor selectively, with an appropriate choice of the electrolyte, different systems: we demonstrate an on-line sensing based on OECTs, with an easy sampling/sample preparation, for the detection of functionalized magnetic nanoparticles.