Wearable and fully printed microfluidic nanosensor for sweat rate, conductivity, and copper detection with healthcare applications.

Wearables are becoming pervasive in our society, but they are still mainly based on physical sensors with just few optical and electrochemical exceptions. Sweat, amongst other body fluids, is easily and non-invasively accessible, abundant, and relatively poor of interfering species. The biomarkers of interest in sweat space from ions and small molecules to whole organisms. Heavy metals have been found being biomarkers of several diseases and pathological conditions. Copper in particular is correlated to Wilson's disease and liver cirrhosis among others. Nevertheless, several issues such as sampling conditions, sweat rate normalization, reliable continuous monitoring, and typically expensive fabrication methods still needs to be addressed in sweat analysis with wearables. Herein, we propose a fully printed wearable microfluidic nanosensor with an integrated wireless smartphone-based readout. Our system can easily be applied on the skin and actively stimulate perspiration, normalizing the heavy metals concentration with respect to the volume of the sample and the sweat rate. The system has a limit of detection of 396 ppb, a linear range up to 2500 ppb and a sensitivity of 2.3 nA/ppb.