TiO2 nanotube arrays fabricated by anodic oxidation had a large surface area and high refraction index. These microstructural properties are very attractive as interferometric biosensing materials. Label free interferometric biosensor usually used nanoporous Si materials. TiO2 nanotube arrays had more stability for wide pH range solutions. The interferometric spectrum from nanoporous layer was treated by Fast Fourier Transform and optical thickness was measured. The optical thickness was changed with the materials in nanoporous layer. To fabricate the TiO2 nanotube arrays, anodizing time, voltage and electrolyte were optimized. The diameter and length of TiO2 nanotube arrays were ~100 nm and ~4 µm, respectively. To observe the loading and elution of the chlorhexidine in TiO2 nanotube in real time, the optical thickness was measured with flow cell system. In 10 wt% chlorhexidine, optical thickness change of ~125 nm was observed.
