There is provided a wearable device for quantitatively detecting a biomarker in a sweat sample obtained from the skin of a subject. The wearable device comprises a microfluidic network. The microfluidic network comprises a reservoir filled with a carrier fluid containing a predetermined amount of a marker； a sample collection chamber disposed downstream from the reservoir and adapted to contact the skin of the subject and collect a sweat sample； a first sensor disposed downstream from the sample collection chamber and adapted to detect the marker； and a second sensor disposed downstream from the first sensor and adapted to detect the biomarker.
