The present invention include non-porous adherent coatings of chemically inert high purity poly-oligomers deposited on substrates. The coatings are applied and cured on the substrates at relatively low temperatures which permits the coating process to be performed with temperature sensitive structures such as magnets, electronic circuits, electrodes, and bonding pads in place on the substrate. Coated substrates, such as sensors and fluid conduits, have an effective thickness of the protective non-porous coating that is chemically bonded to a surface of the substrate that will be contacted with a fluid. The adherent non-porous coating on the substrate protect it from corrosion, particle generation, swelling, or delamination caused by contact with the fluid.