Organic electrochemical transistors (OECTs) have attracted great interest in the last few years as biochemical sensors due to their outstanding analytical performance, versatility, stability, and easiness of fabrication. While thin-film OECTs have been studied extensively, their manufacturing still presents some challenges. This report presents a simple approach for developing OECT using a paper substrate and a thick-film approach that shows outstanding performance. The channel is hand-made by dip pen deposition of the conducting polymer poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS). This allows reproducible channel thickness in the order of 6 μm, well above the conventionally used values. This device displays a high transconductance that exceeds 40 mS and an on-to-off current ratio of 3.8 × 10³ comparable or superior to the state-of-the-art paper-based OECTs. The advantages of this approach are illustrated with the detection of H₂O₂ and glucose, obtaining sensitivities above 1.5 mA/dec. This simplified approach and high sensitivity may help to extend the use of the OECT-based sensors, particularly in the distributed and point-of need applications.

This study reports the development of a simple and sensitive electrochemical sensor based on activated screen-printed electrodes modified by electrodeposition of nickel(II) tetrasulfonated phthalocyanine film (poly-NiTSPc), denoted SPE-A-polyNiTSPc, for the direct determination of BPA in landfill leachate samples. BPA concentrations in raw landfill leachate solutions and in residual solutions after a reverse osmosis (RO) treatment were determined, using differential pulse voltammetry (DPV) on SPE-A-polyNiTSPc, to be 29.7 mgL⁻¹ and 6.4 µgL⁻¹, respectively. The obtained BPA concentrations were very close to those found by the accredited lab in the same samples, which were 29.6 mgL⁻¹ and 6.0 µgL⁻¹, respectively. The applicability of SPE-A-polyNiTSPc for BPA bioremediation was investigated in landfill leachate samples using Trichoderma harzianum fungus in a microbial fuel cell (MFC), where the kinetics data were modeled. The first results showed an IC₅₀ of 175 mgL⁻¹ BPA, indicating that the inhibition factor could be negligeable for MFC experiments at 30 mgL⁻¹ BPA. The biodegradation kinetics was found to be of first order, with a kinetic constant of 0.795 h⁻¹ at 22 °C and a half-degradation time of 0.872 h for an initial concentration of 29 mgL⁻¹. The developed MFC displayed higher stability, offering a maximum power of 100 mWm⁻³.