Sensitivity analysis of a thin-film optical waveguide biochemical sensor using evanescent field absorption

A multichannel thin-film optical waveguide sensor for determining aqueous biochemical concentration with a high dynamic range of measurement is proposed. The sensitivity dependence of the proposed sensor on interaction length and waveguide thickness is investigated for dye solutions and three different hemoglobin concentration levels of carboxyhemoglobins. The sensitivity is inversely proportional to the waveguide thickness while proportional to the interaction length. As a consequence the variability of the interaction length makes the proposed sensor a flexible tool for concentration measurements. Moreover, an efficient method for determining the absorption coefficient is discussed.