Silver decorated CuO-mesoporous graphitic carbon nitride as electrochemical sweat sensor for sensing ammonium ions: A membrane-free voltammetric approach

Abstract

Ammonium ions (NH₄⁺) detection in sweat is important for monitoring metabolic health and hydration levels, offering insights into physiological conditions. This study reported a membrane-free electrochemical sweat sensor based on Ag-CuO-MGCN nanocomposite for detecting NH₄⁺ ions in artificial sweat. The sensor exhibited three linear ranges, 0.01 to 0.05 µM,0.05 to 1 µM, and 1 to 2000 µM with the LOD of 3.82 nM, 63.06 nM, and 0.28 µM for the three concentration ranges, respectively. Real-time recovery studies were conducted using artificial sweat, revealing repeatable and reproducible characteristics. In the probing of NH₄⁺ions, it is witnessed that the CuO gets complexed to ${\left[Cu{\left(N{H}_3\right)}_4\right]}^{2+}$^, resulting in a decreasing trend in the reduction current. The introduction of Ag nanoparticles further supported this steep decrement in the reduction current, which correlates strongly and sensitively even to trace level detection of NH₄⁺ions. In addition, detecting NH₄⁺ions employing the paper screen printed electrode suggests the potentiality of the novel Ag-CuO-MGCN nanointerface in wearable sensing applications. Since the mechanism of NH₄⁺ions detection in the artificial sweat stands novel, this proof of concept study opens a way forward to advancing biosensing technologies for personalized health monitoring.