“…These sweat glands produce and excrete an acidic fluid directly to the outer skin surface through microscale pores [23,68]. Moreover, sweat includes various molecules, e.g., lactate [133,[138][139][140], glucose [69,134,137,141,142], cortisol [23,54,135,[142][143][144], testosterone [23], uric acid, as well as larger molecules, like proteins, peptides, and cytokines [24,54,142], Additionally, the detection of analytes in sweat is feasible due to the given correlation between the blood analyte concentration and the excreted sweat analyte concentration [138,145,146]. For analytes like hormones (cortisol, testosterone), potassium, and different drugs, e.g., alcohol, a strong sweat-blood correlation was proven [23].…”