Organic electrochemical transistor-based biosensors using doped polyaniline

Abstract

The development of high-performance biosensors is essential for advancing health monitoring in aging societies and for ensuring safety in food and environmental systems. Among various sensing platforms, organic electrochemical transistors (OECTs) stand out as especially promising because of their intrinsic signal amplification, high sensitivity, biocompatibility, and low-voltage operation.Here, we report a class of OECT-based biosensors that utilize polyaniline (PANI) films doped with 4-sulfophthalic acid (SPA) and phenol 4-sulfonic acid (PSA), achieving improved electrical conductivity from 0.2 S cm -1 (pristine PANI) to 36 S cm -1 (PANI-SPA) and 56 S cm -1 (PANI-PSA), enhanced redox activity, and superior morphological robustness. Comprehensive characterization using transfer characteristics, cyclic voltammetry, and atomic force microscopy confirmed that the doped PANI films exhibited enhanced conductivity, surface homogeneity, and electrochemical stability. More importantly, the doped OECTs demonstrated sensitive detection of biologically relevant analytes, such as ascorbic acid (AA), uric acid (UA), and dopamine (DA).Shifts in transfer curves and changes in transconductance (g m,max up to 0.19 mS for PANI-SPA with AA and 0.24 mS for PANI-PSA with DA) revealed distinct interaction profiles for each doped film-analyte pair, corresponding to strong molecular interactions and oxidation potential shifts. In summary, these findings highlight a feasible strategy for designing OECT biosensors with tunable selectivity and robust performance.