An electrochemical test device for determining the presence or concentration of an analyte in an aqueous fluid sample comprises a substrate comprising a non-conductive material; a working electrode comprising a conductive film formed at least with carbon nanotubes, the working electrode having a first electrode area, a first lead and a first contact pad; a counter electrode comprising a conductive film formed at least with carbon nanotubes; a reagent capable of reacting with the analyte to produce a measurable change in potential which can be correlated to the presence or concentration of the analyte in the fluid sample, the reagent overlaying at least a portion of the first electrode area of the working electrode; and a reference electrode comprising a conductive coating formed at least with carbon nanotubes, the reference electrode having a third electrode area at least a portion of which is overlaid with a reference material.