Fig. 1.

Fabrication scheme and POM images of DNA films on a flat/micropost-patterned substrate. a Simply dried DNA film on the flat Si substrate and b its POM image. c–e Enlarged images from b show distinctive colours depending on the position of the DNA film, and the corresponding orientation of DNA chains. f Hydrated DNA film on the microposts and g its POM image. h–j Enlarged images from g show the different patterned textures depending on the drying direction. Black scale bars represent 400 μm and white ones are 20 μm