Abstract: Some implementations of the disclosure relate to a wearable biosensor device including an iontophoresis module configured to stimulate production of a sweat sample from skin of a user, the sweat sample including biomarkers; a microfluidic module configured to collect the sweat sample, mix the sweat sample with labeled detection reagents to obtain a mixture including the biomarkers bound to the labeled detection reagents, and route the mixture to a detection reservoir of the microfluidic module; and a sensor assembly including a bioaffinity sensor configured to quantify the biomarkers of the mixture in the detection reservoir to determine a concentration of the biomarkers present in the sweat sample. The bioaffinity sensor includes an electrode functionalized to bind to the biomarkers of the mixture. The bioaffinity sensor can quantify the biomarkers to determine their concentration with a sensitivity on the order nanomoles or picomoles.