Water contact angles were measured using a MCA-3 Microscopic Contact Angle Goniometer (Kyowa Interface Science). Droplets of water (~ 0.5 μL) were dispensed using a glass capillary with a 50 μm tip diameter. Images were recorded with a calibrated side camera (640 x 480 pixels, 6.97 μm/pixel) at 40 frames per seconds.