Biochemical sensors based on thin-film waveguide

Biochemical sensors based on thin-film waveguide are proposed which can measure the concentration of sample solutions. In order to investigate the applicability of these sensors to Ca²⁺ and glucose measurement, the waveguide was fabricated with 3 layers: the substrate (pyrex glass), the waveguide layer (sputtered with Corning 7059 glass) and sample layer having PVC sensing membrane and/or sample chamber. We applied the sensor to sample a solution whose CaCl₂ concentration was gradually altered. Also, we applied it to red colored glucose solutions. In this experiment, we found that the thin-film waveguide sensor possessed high sensitivity at 488 nm of argon laser. In addition, our glucose sensor could measure a wide range of glucose concentrations from 0 mg/dl to 750 mg/dl and Ca²⁺ could be measured from 10^-5 mol to 10^-0 mol. The sensitivity of this waveguide sensor is increased by the interaction length which means the reaction area between the evanescent field of propagated light and the sample layer. These findings suggested that the proposed waveguide biochemical sensors are applicable to various samples