High spatial resolution label-free detection of antigen-antibody binding on patterned surface by imaging ellipsometry

► Large area protein micro-arrays with feature size down to 8 × 8 μm2 square spots could be clearly imaged by imaging ellipsometry. ► By using different patterns, 100-1600 label-free protein spots were imaged simultaneously. ► The thickness changes during the formation of protein patterns were quantitatively monitored on the 32 × 32 μm2 square spots. ► Quantitatively ellipsometric measurements were performed on protein arrays with densities above 5 × 104 spot/cm2. ► A single spot detection limit as low as 1.2 pg/spot was achieved.