ZnO micron rods as single dielectric resonator for optical sensing

Light scattering properties of dielectric nanostructures (DNSs) have been recently applied for biosensing. It is worth noting that, however, the application of dielectric materials as light scattering probes in the field of analysis and detection has rarely been reported, especially at the single particle level. Herein, for the first time, we use ZnO micron rods (ZnOMRs) as dark field microscope (DFM) imaging probes for single particle level optical sensing. It was found that a drastic reduction of scattering intensity of the ZnOMRs with increase of the surrounding medium's refractive index (RI), especially when illuminated by transverse electric (TE) polarized light, showing polarization-dependent RI sensitivity properties. In addition, the scattering color of the ZnOMRs gradually blue-shifted with the increase of solvents' RI, this can avoid the problem of low sensitivity of the probe with a red scattering color in the previous reports. The characteristic scattering properties and polarization-dependent RI sensitivity properties of ZnOMRs provide more possibilities for the development of new single-particle optical analytical methods.