Wearable microfluidic electrochemical sensor integrated with iontophoresis for non-invasive sweat ketone monitoring

The detection of β-hydroxybutyrate (β-HB) is crucial for the rapid diagnosis of diabetic ketoacidosis and health management. However, daily monitoring of dynamically changing β-HB concentrations is challenging and still limited to laboratory settings or painful and invasive measurements. Herein, we report a wearable electrochemical sensor integrated with iontophoresis for non-invasive monitoring of sweat β-HB. This device can actively stimulate the skin to induce sweat by iontophoresis, and the sweat is controllably collected and transported to the sensing area through the microfluidic channel. The sweat β-HB was measured through an electrochemical oxidation reaction mediated by the generated nicotinamide adenine dinucleotide, which can achieve fast response analysis of sweat β-HB within 40   seconds and a low detection limit of 10   μM. We also used this sensor to monitor the sweat β-HB levels in a volunteer experiencing the ketogenic diet and the sweat and blood β-HB levels exhibited high correlation. We believe this wearable sensor capable of on-demand and noninvasive detection of sweat β-HB shows a wide application prospect in clinical medicine and home healthcare.