The aim of our research is to develop a sensitive sensor for biomedical applications. A nanolayer Al2O3 is used as evanescent waveguide. The material was deposited on a silicon wafer by using atomic layer deposition (ALD). In the present paper, we will report the preliminary results of our project such as deposition, characterization of nanolayer, and evanescent waveguide sensor design. Lambert beer's law and some waveguide concepts are combined in the design to obtain the optimum parameters of the evanescent waveguide sensor. Furthermore, characterizations to investigate optical properties and internal stress of the thin film were done. Based on the results of lattice parameter analysis, we can conclude that thin film thickness have effect not only on sensitivity of the sensor but also on the mismatch stress between substrate and thin film. Design results show that a thickness of waveguide of 50 nm and an optical path length of the sensor of 1 mm can be used as waveguide dimension with a transmission of 75%. 50 nm thin film thickness shows low mismatch stress and that was shown by high radius curvature 32.34 m.