Unveiling the effect of paper matrix on the electrochemical response of diffusive redox probes

Abstract

This study investigates how different paper substrates affect the electrochemical response of paper-based analytical devices (ePADs) using chronoamperometry. Both theoretical modelling and experimental analyses were conducted to understand the diffusion behaviour of two redox probes, [Fe(CN)6]3- and ferrocenemethanol (FcMeOH). Findings suggest that glass fibre substrates demonstrate the most favourable electrochemical performance, while nitrocellulose substrates show a significant decrease in current after the first 10 seconds due to the thin-layer effect. Cellulose-based substrates decrease the diffusivity of redox species, especially for charged species, indicating potential limitations in their use for chronoamperometric measurements. The study offers valuable insights into the electrochemical behaviour of paper substrates in ePADs, laying the groundwork for future research in this area.