Controlled sweat generation via ultrasound stimulation integrated in a wearable device

Wearable sweat biosensors enable noninvasive molecular monitoring, but reliable and comfortable on-demand sweat induction remains challenging. We developed a soft, skin-conformal wearable device that integrates ultrasound-assisted sweat generation with electrochemical sensing. Low-frequency ultrasound enhanced transdermal delivery of carbachol from a hydrogel reservoir, inducing localized sweat secretion under resting conditions without electrical current or skin penetration. Under the matched 15-min experimental window used here, ultrasound-induced sweating showed lower observed skin irritation and more favorable user-rated comfort than the tested iontophoresis setting. Integrated sensors measured uric acid, pH and K+ in ultrasound-induced sweat, and sweat uric acid showed a positive correlation with serum levels in a preliminary human study. These results support wearable ultrasound as a low-irritation strategy for controlled sweat generation and downstream biomarker tracking under resting conditions.