Development of a reagent-free electrochemical disposable sensor strip for the quantification of sweat chloride

In this work, we developed a reagent-free disposable sweat chloride sensor using silver platinum reduced graphene oxide composite. The sensing mechanism involves the silver chloride formation from electro-oxidized silver in the presence of chloride ions. The combination of platinum with silver and reduced graphene oxide resulted in an approximately sixfold increase in sensitivity, significantly enhancing the sensor performance. The developed disposable strip exhibited an excellent sensitivity of 6.592 +/- 0.007 and 17.420 +/- 0.011 mA (log mM)- 1 cm- 2 for 5-40 mM and 40-200 mM chloride concentration ranges, respectively with a detection limit of 12 mu M. The developed sensor exhibited exceptional selectivity against interfering molecules in sweat samples. The practical applicability of the developed sensor was evaluated in sweat samples, revealing an outstanding sensitivity of 0.901 +/- 0.007 mA (log mM)- 1 cm- 2 for detecting sweat chloride ions. The estimated chloride concentrations are in good agreement with the clinically tested values with a relative error of less than 1.5%. The performance of the fabricated Ag-Pt/rGO/SPE sensor opens advanced point-of-care testing opportunities through non-invasive, and convenient analysis.