Superhydrophilic surface of oxidized freestanding CVD diamond films: Preparation and application to test solution conductivity

This work reports the surface features, wettability properties and application of the thermally oxidized freestanding chemical vapor deposited diamond films. The oxygen-terminated micrometer-sized diamond grains on growth side and the pyramid-shaped diamond nanotips on nucleation side of diamond films, having superhydrophilic feature, are realized by a thermal oxidation treatment process in air. The superhydrophilic surfaces were proposed to examine the conductivity properties of micro-solution droplets (with varying ion concentrations) spreading fast on the film surface. The corresponding conductivities of the micro-solutions are nearly linearly increased with increasing the ion-concentration in a large region. It is demonstrated that the chemical inert diamond films with the functionalized surfaces are favorable for fabricating high efficient, sensitive, and washable detectors.