Abstract: One example device includes a housing attachable to a wearer's skin; a electrode assembly holder disposed within the housing, the electrode assembly holder comprising: a substrate; a plurality of electrical contacts formed on the substrate; and an electrode assembly electrically coupled to the plurality of electrical contacts, the electrode assembly having a planar surface and comprising: a first screen-printed electrode having first and second ends; a chemical sensing material disposed on the first end of the electrode; and a polymer coating applied to the electrode; and wherein the first end of the screen-printed electrode extends outside of the housing and wherein a second end of each electrode is electrically coupled to one electrical contact of the plurality of electrical contacts.