Of microsphere lenses, introduce 3 kinds of microsphere lenses, concentrate on the applications of microsphere lenses in optical trapping, sensing, and imaging, and go over potential application scenarios.Photonics 2021, eight,3 of2. Kinds and Principles of Microsphere Superlenses 2.1. Varieties of Microspheres Microsphere superlenses could be classified by the medium in which the microspheres exist: microspheres in air medium, microspheres in liquid medium, and microspheres in strong medium. In 2011, SiO2 microspheres with a refractive index of 1.46 and diameter of two have been straight placed on the surface of a sample by self-assembly technology to achieve superresolution imaging of gold-plated oxide anodic alumina film using a spacing of 50 nm beneath a light supply with a wavelength of 600 nm [44], as shown in Figure 1a. The microsphere lens allows for the collection of details about the object inside the near field along with the formation of a magnified virtual image in the far field. A resolution of /814 in addition to a magnification of is often achieved within the air medium. Furthermore, in accordance with theoretical calculations, the super-resolution intensity of microspheres having a refractive index of 1.8 was greatest in air. When the refractive index increases to 2.0, the super-resolution capability of microspheres becomes smaller. This demonstrates that not all microspheres have super-resolution capabilities; only microspheres that meet GNF6702 Parasite precise conditions can generate photonic nanojets to achieve super-resolution imaging. Microspheres in liquid media might be classified into two groups: semi-immersed in liquid and totally immersed in liquid. The experimental setup diagram is shown in Figure 1b [59]. Hao et al. showed that when SiO2 microspheres having a refractive index of 1.47 and diameter of three were completely submerged in an ethanol resolution, the microspheres did not have super-resolution capabilities [60]. When part of the ethanol option was volatilized and also the microspheres had been semi-submerged inside the option, the contrast and resolution from the virtual image on the tested sample had been enhanced, allowing imaging of industrial blue light discs with a width of 100 nm. When the ethanol remedy was nearly evaporated as well as the microspheres were exposed to air, the resolution became weaker, further demonstrating that semi-immersion with the microspheres in liquid could enhance the resolution of imaging. Even so, the volatility in the ethanol resolution was not conducive to a prolonged observation with the experiment. Darafsheh et al. then demonstrated that super-resolution imaging may be accomplished when high refractive index microspheres have been absolutely submerged in a liquid answer [61,62]. Barium titanate (BaTiO3 ) microspheres using a refractive index of 1.9 were absolutely submerged in an isopropyl alcohol solution having a refractive index of 1.37, and also the super-resolution imaging of two-dimensional gold nanodimers comprising gold nanopillars using a diameter of 120 nm and height of 30 nm was accomplished below an SBP-3264 Purity & Documentation illumination light source with a wavelength of 550 nm. In 2014, the team demonstrated that the imaging effect BaTiO3 microspheres having a refractive index of two.1 submerged in an isopropane alcohol option was superior than that of soda lime glass using a refractive index of 1.51 in air [63]. Furthermore, Darafsheh et al. proved that high refractive index microspheres embedded inside a transparent film can attain super-resolution imaging [64]. The experimental setup of microspheres in.