Concentric Circular Grating Generated by the Patterning Trapping of Nanoparticles in an Optofluidic Chip.

Hailang Dai,Yuxing Wang,Minghuang Sang,Zhuangqi Cao,Fan Chen,Xianfeng Chen,Wen Yuan,Honggen Li

doi:10.1038/srep32018

Abstract

Due to the field enhancement effect of the hollow-core metal-cladded optical waveguide chip, massive nanoparticles in a solvent are effectively trapped via exciting ultrahigh order modes. A concentric ring structure of the trapped nanoparticles is obtained since the excited modes are omnidirectional at small incident angle. During the process of solvent evaporation, the nanoparticles remain well trapped since the excitation condition of the optical modes is still valid, and a concentric circular grating consisting of deposited nanoparticles can be produced by this approach. Experiments via scanning electron microscopy, atomic force microscopy and diffraction of a probe laser confirmed the above hypothesis. This technique provides an alternative strategy to enable effective trapping of dielectric particles with low-intensity nonfocused illumination, and a better understanding of the correlation between the guided modes in an optical waveguide and the nanoparticles in a solvent.

Highlights

Among these trapping techniques, optical tweezers are widely used for various optical micromanipulation applications
A hollow-core metal-cladded waveguide (HCMW) chip of millimeter-scale was used as a fluid-transport channel, and the unique ultrahigh-order modes (UOMs)[23] are excited to realize the trapping of the nano-particles in the fluid
We presented an experiment to demonstrate the concentric circular grating of the trapped nanoparticles by the diffraction pattern of a scattered beam

Summary

Optofluidic Chip

Hailang Dai[1], Zhuangqi Cao[1], Yuxing Wang[1], Honggen Li1, Minghuang Sang[2], Wen Yuan[2], Fan Chen3 & Xianfeng Chen[1]. Experiments via scanning electron microscopy, atomic force microscopy and diffraction of a probe laser confirmed the above hypothesis This technique provides an alternative strategy to enable effective trapping of dielectric particles with low-intensity nonfocused illumination, and a better understanding of the correlation between the guided modes in an optical waveguide and the nanoparticles in a solvent. Large quantities of nanoparticles can be trapped in a concentric circular pattern, which follows the field distribution of the UOMs. Compared with other approaches, our method does not require high NA lenses or high incident power of laser. A better understanding of the interaction between the optical guided modes and the nanoparticles in the optofluidic chip is provided

Results and Discussion

Conclusions

Author Contributions

Additional Information