Influence of graphene-based ink formulation on the performance of inkjet-printed electrochemical sensors for detecting water contaminants of emerging concern

Inkjet printing has emerged as a promising approach for the fabrication of low-cost and scalable electrochemical sensors, particularly when carbon-based nanomaterials are used. This study investigates the influence of graphene-based ink formulation on the performance of inkjet-printed sensors designed for the detection of acetaminophen, a pharmaceutical product identified as a water contaminant of emerging concern. Two ink formulations were prepared, each containing an aqueous graphene oxide suspension as the functional material, Triton X-100 as a surfactant, and carbon black as a conductive additive. However, they differed in their solvent systems, with the aim of optimising both, ink printability and the electrochemical response of the resulting sensors. The printed electrodes' morphology, pattern topography/uniformity, electrical conductivity, surface chemistry and electrochemical performance toward target analyte were characterized. Our findings reveal that ink composition significantly impacts film uniformity, electron transfer kinetics, and overall sensor performance. The formulation incorporating a mixed solvent system (water, glycerol, ethylene glycol) exhibited superior performance, achieving lower detection limits (LOD ∼ 0.572 μM) and enhanced reproducibility and repeatability (% RSD ∼ 5.3 and 5.7, respectively) for acetaminophen sensing. These results highlight that rational ink formulation is not merely an optimization parameter, but a decisive design factor that markedly influences the performance of printed electrochemical sensors, establishing it as a critical element for advancing reliable and high-impact environmental monitoring technologies.