Utilising highly conductive TPU "sticks" for facile and low-cost electroanalysis

Rapid, on-site analysis of environmental contaminants necessitates the use of cost-effective and straightforward apparatus to encourage widespread adoption and align with the United Nations Sustainable Development Goal 6: Clean Water and Sanitation. In this work, we report the development of highly conductive thermoplastic polyurethane (TPU) filaments that can be easily cut and assembled into "sticks", functioning as standalone rod-like working electrodes for electrochemical and electroanalytical applications. Using TPU as the base polymer, filaments filled with 35, 40, and 45 wt% carbon black (CB) were fabricated and characterised both physicochemically and electrochemically at different lengths (2.5, 5 and 10 mm). Among these, the 45 wt% CB filaments demonstrated the best electrode performance. Interestingly, due to morphological differences between the cross-section and the outer surface of the filament, extending the length of the filament sticks to 10 mm resulted in significant splitting of electrochemical peaks. Consequently, 5 mm sticks were optimised and employed for the electroanalytical detection of acetaminophen, achieving a linear detection range of 5-800 μM, a detection limit of 1.74 μM, and a quantification limit of 5.70 μM. These sticks were further validated by successfully detecting acetaminophen in tap and river water samples. This work introduces an innovative approach to reducing costs and simplifying on-site electrochemical analysis by using predefined lengths of conductive plastic filaments, which can be conveniently transported and stored on a spool until needed. The simplicity and affordability of this method enhance the commercial viability of electroanalytical sensing technologies.