Synthesis of High Refractive Index and Shape Controllable Colloidal Polymer Microspheres for Super-Resolution Imaging

A conventional optical microscope fails to resolve features with sizes smaller than 200 nm due to the Abbe diffraction limit. Herein, we synthesize two kinds of high refractive index and shape controllable colloidal polymer microspheres, poly(9,9′-bis[4-(2-acryloyloxyethyloxy)phenyl]fluorene) (poly(BAEPF)) and poly(2-phenylphenoxyethyl acrylate) (poly(OPPEA)), used for solid immersion lens. It is the high refractive index and close contact with the surface features that can make the colloidal polymer microsphere-based microlens effectively collect evanescent information on the substrate and form a clear and magnified virtual image at certain position below the substrate surface. Thus, as small as 60 nm feature size on the substrate can be clearly resolved through the microlens under a visible light optical microscope, which is far beyond the resolution limit of a visible light microscope.