Adv. Funct. Mater. 29, 1903340 (2019)

Naturally evolved eyes have their strengths and weaknesses. Compound eyes allow insects to see over a wide range of angles, but the fixed focal length limits resolution and depth perception. Vertebrate eyes, on the other hand, are varifocal but have a small field of view. Zhuo-Chen Ma and colleagues have combined the two principles and made an artificial compound lens with variable focal length.

The lens comprises approximately 80 individual facets arranged in a hexagonal pattern — similar to a dragonfly eye — and was fabricated from the protein bovine serum albumin using direct laser lithography. The protein reacts to a change in the pH value of its environment by swelling or shrinking and therefore with a change of focus and of the viewing angle. But when the team placed the lens on top of a polymer dome, whose shape stayed unaltered, the field of view remained constant while the focus was adjusted.