Wettability characterization method based on optical coherence tomography imaging

A novel method for surface wetting characterization based on contact angle measurements is presented. Three dimensional structural imaging of a droplet on a substrate is performed using optical coherence tomography (OCT) which provides micrometer resolution images without contact with the sample. An automatic OCT intensity variation based, layer segmentation method was implemented to identify air-droplet, droplet-substrate and air-substrate interfaces. A glycerol droplet on a rough tilted glass substrate was used as a test sample to demonstrate the applicability of the proposed method for wetting characterization. Results show that the contact angle of any observation angle can be obtained. In addition, the droplet's average refractive index can be determined. The proposed method is an interesting and complementary tool for present wetting characterization methods.