Real-time nanomolar vitamin monitoring in sweat using an electrochemical skin-attached device.

Invasive and inconvenient blood tests hinder the diagnosis and treatment of micronutrient deficiencies, which affect billions worldwide. Wearable sweat sensors offer a noninvasive and real-time alternative. However, on-body monitoring of multiple low-abundance vitamins in sweat remains challenging. Here, we show a wearable electrochemical platform that utilizes bioreceptor-functionalized gold nanoflower/sulfur and nitrogen codoped carbon to detect six low-concentration vitamins in sweat (vitamins B1, B2, B7, B9, B12, and D) with nanomolar-level sensitivity. Integrated system incorporates iontophoretic sweat induction, microfluidic sampling and real-time vitamin detection with calibration. Human studies revealed temporal profiles of VB9 levels in sweat in response to oral VB9 supplementation and VB9-rich diets, and a strong sweat-serum correlation (r = 0.849) has been found. The significant differences in VB9 levels observed between smokers and nonsmokers demonstrated the potential of this technology for vitamin monitoring in diverse populations. Our platform facilitates early detection of nutritional imbalances and advances personalized nutrition.