Comparison of Spray-Coating and Drop-Casting of PEDOT:PSS on Interdigitated Electrodes for Improved Interface Characteristics in Biosensors

Poly (3, 4-ethylenedioxythiophene) -poly (styrene sulfonate) (PEDOT: PSS) is a conductive polymer yielding promising interface characteristics for biosensor electrodes. In this work, we compare two solution processing methods, namely drop-casting and spray-coating, for the deposition of PEDOT: PSS layers on gold interdigitated electrodes for electrical impedance spectroscopy based biosensing applications in fluid. Both techniques include (3-glycidyloxypropyl) trimethoxysilane (GOPS) as a crosslinker and reveal good stability in electrolytes. On the one hand, spray coating shows higher mechanical robustness, reproducibility, and better layer thickness control. On the other hand, drop-casting yields a 3-fold lower surface roughness and results in improved double-layer characteristics with a capacitance of 157 F compared to 3 F of bare gold. Both deposition techniques promise higher electrode reproducibility and improved interface characteristics, especially in the lower frequency range.