Fig. 4. Contamination and self-cleaning of superhydrophobic microstructured SU-8 pillars (rectangular, 10-μm height with 5 × 5–μm² top areas; center-center distance of pillars, 20 μm).

(A) LSCM (top) and SEM (bottom) images showing a surface contaminated with 1.5-μm particles. On the left side of the SEM image, the micropillar array is only partially filled with particles (h_c < h_P), whereas on the right, the particles completely covered the microstructure (h_c > h_P). Scale bar, 10 μm (SEM). (B) Roll-off angles of 6-μl water drops after contamination of the micropillar array with hydrophilic and hydrophobic particles of various sizes and subsequent self-cleaning.