Ziyu Yin1,Tyler Ray1
University of Hawaii1
Sweat contains a wealth of biomarkers relevant to health status, including electrolytes, metabolites, organic compounds, inflammatory/stress biomarkers, proteins, and hormones. Knowledge of such physiological parameters provides important insights into the dynamic state of health, hydration, fatigue, and overall well-being. Many target sweat biomarkers are present only in extremely low concentrations necessitating sophisticated sensing materials and detection strategies to obtain high-fidelity measurements of target biochemical signals. Materials, such as high-entropy oxides, offer significant promise for the detection of such species of interest with both high specificity and sensitivity while eliminating the limitations and environmental susceptibility inherent with commonly-employed enzymatic sensing approaches. Here, we present a novel one-pot synthesis of high entropy (Fe, Co, Mn, Ni, Cu)<sub>3</sub>O<sub>4</sub> oxide (HEO) sensing material via a microwave-assisted reaction, which exhibits a microporous bulky morphology with a single-phase, face-centered cubic (FCC) spinel structure. We utilize the unique physical and catalytic properties of this transition-metal-based HEO as a sensing material which, when integrated with a screen-printing electrode, is suitable for detecting targeted sweat biomarkers (i.e., glucose/cortisol). We detail the catalytic mechanisms of this functional material, specifically the chemical structure, geometry, and electrochemical properties, and characterize sensor performance with respect to these sweat biomarkers through on-body testing.