Superhydrophilicity on microstructured titanium surfaces via a superficial titania layer with interconnected nanoscale pores.

Microstructured titanium (Ti) surfaces often suffer from poor hydrophilicity which makes the realization of open microfluidic devices difficult. Here, we investigate the effect of a superficial porous titania (TiO2) layer on the hydrophilicity of microstructured surfaces. High aspect ratio Ti micropillars were micromachined from bulk Ti sheets. Porous TiO2 was subsequently grown on Ti micropillars by a wet oxidation route followed by thermal annealing. Porous TiO2 was characterized using atomic force microscopy, x-ray diffraction and x-ray photoelectron spectroscopy. Detailed morphology study and pore size analysis were carried using focused ion beam machining coupled with scanning electron microscopy. Static contact angle and dynamic spreading studies clearly demonstrate enhanced hydrophilicity of microstructured Ti surfaces with a superficial porous TiO2 layer. Such enhancement promises interesting applications in the microfluidics and microsystems fields.