The present invention provides a transparent polyimide substrate comprising a transparent polyimide film and a cured layer of a polyisocyanate formed on at least one surface of the transparent polyimide film, the polyisocyanate containing an acrylate group and having 2 to 5 isocyanate groups per molecule. In such construction, Q comprises one or more refractory metals, R is selected from the group consisting of one or more of tungsten, aluminum and silicon, S is selected from the group consisting of one or more of nitrogen and oxygen, and B is boron. Appropriate action may be taken based on this measurement, for instance in disclosed methods. Each health monitoring sensor node has a tunable antenna arrangement individually tunable to minimize data collisions between each other of the health monitoring sensor nodes.