A wearable medical device for collecting a biofluid and related methods are disclosed. The device has a patch adapted to removably couple to a user's skin. The patch has at least one flow channel, at least one sample chamber, and at least one biomarker detection chamber. The flow channel and/or the sample chamber conducts the biofluid towards the biomarker detection chamber. The sample chamber is adapted to create a high humidity environment adjacent the user's skin. The flow channel comprises a hydrophobic material and a hydrophilic material.
