Sub‐Diffraction and Irreversibly Tunable Imaging With Potato Starch Lenses

ABSTRACT

Biological microstructures offer sustainable and functional platforms for photonic applications. In this work, potato starch granules are shown to act as natural microlenses, capable of modulating both the dynamic and geometric phases of light. Their intrinsic radial birefringence and spherical shape enable simultaneous spin‐to‐orbital angular momentum conversion and efficient light focusing, giving rise to polarization‐controlled conventional and vortex lensing. When dispersed over the specimen surface, the granules locally transform the incident field, enabling sub‐diffraction and contrast‐enhanced imaging in conventional and vortex modes. Sub‐diffraction information is retrieved from the fields of view of individual granules, which may be randomly distributed or arranged in ordered arrays generating vortices with controlled handedness. Exploiting vortex lensing, the method produces spiral‐contrast images, revealing structural features of buccal epithelial cells. Thermally controlled water swelling facilitates one‐way tuning of the focal length. Resulting structural disruption deactivates vortex formation and allows starch post‐performance enzyme‐triggered disintegration. These results establish starch granules as a sustainable and reconfigurable micro‐photonic platform, inspiring a new class of adaptive or transient optical components.