A modularized and flexible sensor based on MWCNT/PDMS composite film for on-site electrochemical analysis

Flexible sensors based on multi-walled carbon nanotubes (MWCNTs) and their composite materials are widely applied to develop strain sensors that generate a signal as a function of the physical or mechanical deformation. However, on-site analysis of the electrochemical active substances with the flexible electrodes during the biological or medical processes remains a great challenge for current electrochemical technologies. Herein, a universal three-electrode module, adaptable of the synchronous electrochemical analysis in practical applications has been developed with the MWCNTs and polydimethylsiloxane (PDMS) flexible film as the working and the counter electrodes and a painted silver-paste line as the pseudo-reference electrode. The MWCNT/PDMS flexible eletrodes capable of being customized into various sizes, shapes and geometries according to the detection environmental requirements, were prepared through a simple molding transfer method and endowed the on-site electrochemical analysis module with a great potential on the curved surface or in the repeatedly bending situation. Finally, in a 24-well plate and a medical drip which were equipped with the developed three-electrode module, the concentrations of dopamine (DA), uric acid (UA) and nicotinamide adenine dinucleotide (NADH) were successfully detected by Differential Pulse Voltammetry (DPV) with robust stability and repeatability. The technique developed in this study offers an accurate and cost-effective on-site electrochemical analysis system that can be modularly adjoined into various biological and medical applications.