An apparatus is used for determining at least one parameter relating to an elongate member disposed within a vessel. A first protective layer is formed on the top surface of the semiconductor die, the first protective layer having a plurality of first apertures for allowing the metal pads to be opened upward. A lattice pattern is then formed within the radiation-imageable layer, with the lattice pattern defining a plurality of islands of the radiation-imageable layer. , various salts, sugars, water-soluble polymers, such as polyvinyl alcohol. An output voltage at the light source is measured, and compared to the corresponding voltage of the selected duty cycle to produce a voltage comparison result.