Wide‐Field and Real‐Time Super‐Resolution Optical Imaging By Titanium Dioxide Nanoparticle‐Assembled Solid Immersion Lens

Abstract Super‐resolution optical imaging techniques can break the optical diffraction limit, thus providing unique opportunities to visualize the microscopic world at the nanoscale. Although near‐field optical microscopy techniques have been proven to achieve significantly improved imaging resolution, most near‐field approaches still suffer from a narrow field of view (FOV) or difficulty in obtaining wide‐field images in real time, which may limit their widespread and diverse applications. Here, the authors experimentally demonstrate an optical microscope magnification and image enhancement approach by using a submillimeter‐sized solid immersion lens (SIL) assembled by densely‐packed 15 nm TiO₂ nanoparticles through a silicone oil two‐step dehydration method. This TiO₂ nanoparticle‐assembled SIL can achieve both high transparency and high refractive index, as well as sufficient mechanical strength and easy‐to‐handle size, thus providing a fast, wide‐field, real‐time, non‐destructive, and low‐cost solution for improving the quality of optical microscopic observation of a variety of samples, including nanomaterials, cancer cells, and living cells or bacteria under conventional optical microscopes. This study provides an attractive alternative to simplify the fabrication and applications of high‐performance SILs.