Single-Step Modified Electrodes for Vitamin C Monitoring in Sweat

Abstract

We demonstrate a flexible sensor for ascorbic acid detection in sweat based on single-step modified gold microelectrodes. The modification consists on the electrodeposition of alginate membrane with trapped CuO nanoparticles on top of the electrodes. The electrodes are fabricated at a thin polyimide support and the soft nature of the membrane can withstand mechanical stress far beyond the requirements for skin monitoring. We further show the efficient detection of ascorbic acid at the micromolar levels in both, a neutral buffer and acidic artificial sweat, at ultra-low applied potential (-5 mV). The effect of possible interfering species present in sweat is minimized, with no observable cross-reaction, thus maintaining a high degree of selectivity despite absence of enzymes in the fabrication scheme. This sensor is envisioned as a promising component of a wearable device for e.g. non-invasive monitoring of micronutrient loss through sweat.

Electrochemical detection of ascorbic acid in artificial sweat using a flexible alginate/CuO-modified electrode

“…Here, we report on a new ascorbic acid sensor that combines for the first time the rapid fabrication possibility of the alginate membrane with the encapsulation of the commercially available CuO NPs to exploit their ascorbic acid oxidizing capabilities. The sensor is fabricated via electrodeposition of an alginate membrane using a precursor mixed with CuO NPs on gold electrodes evaporated on a light-weight polyimide support [42]. The alginate membrane, which is reported to be biocompatible and permeable to the diffusion of the electrochemical substrates but impermeable to cells or large particles, has previously been used to trap enzymes for glucose and lactate determination [17,43] and carbon nanotubes to measure microbial activity [44].…”