Microfabrication processes of defectless TiO2 waveguides for insertion of a microfluidic channel

Integration of waveguides and microfluidic channels enables construction of weak fluorescence detection system at a chip size. Crossed structure of a waveguide and a microfluidic channel can achieve small detection volume, which contributes to reduction of sample consumption and separation of each molecule. The decrease of defects caused by fabrication processes is indispensable because of efficient light propagation in the waveguides. In the present study, we develop microfabrication processes for bisection of waveguides consisting of titanium dioxide (TiO₂) cores and silicon dioxide (SiO₂) claddings by microfluidic channels without defect. The processes exclude unintended etching on the claddings and selectively remove small residues in the microfluidic channels caused by etching.