Prolonged and localized sweat stimulation by iontophoretic delivery of the slowly-metabolized cholinergic agent carbachol

Eccrine sweat has recently been gaining significant attention as a non-invasive method to access many electrolyte, molecule, and protein analytes found in blood [1]. Such attention builds on established commercial use of sweat for cystic fibrosis testing [2] and testing for metabolites of drugs of abuse [3,4]. The recent surge of interest in sweat biosensing has been caused by a demand for wearable technology that can continuously measure chemical analytes, and because sweat has several inherent advantages compared to other non-invasive biofluids [5–9].