Author:    2015-12-02

The light scattering of a particle is a significant characteristic for various applications, such as environmental monitoring, biomedical diagnosis and cytological analysis. Common methods of scattering measurement have mainly focused on volume scattering of the particle group. However, studies on light scattering at the single-particle level are significant for accurate counting, morphological analysis, or inner structure exploration in certain applications. Moreover, theoretical developments of particle scattering, requires a practical, stable, and direct verification of single-particle-scattering experimentally in a wide angular range. Electrodynamic balance (EDB) utilizing the electrostatic well and dual-beam optical tweezer employing the optical gradient force has been reported as tools assisting the angular-resolved single-particle-scattering measurements by capturing the charged single aerosol particle/droplet or the single microscopic particle suspended in the solution. However, the EDB-based capturing has been rarely reported in the conductive environment; the dual-beam optical tweezer relied on the complex optics-particle interaction, which is sensitive to many environmental factors, dependent on the manual steering, expensive and bulky on the view of setting. Hence, it’s significant to develop an effective approach/instrument to rapidly detect the single-particle-scattering.

Under the guidance of Wuhan National Laboratory for Optoelectronics Professor Kecheng Yang and Associated Professor Min Xia, doctor Jie Dai, master Baoyu Gong and Huimin Wang developed a new angular-resolved detection method of single-particle scattering based on a microfluidic trap by studying the model of Micro-Nano hydromechanics and particle scattering. A Polydimethylsiloxane hydrodynamic network was designed, optimized and fabricated to rapidly and stably trap the single polystyrene particle of 20μm-30μm with a self-regulation. The weak scattering light of the single trapped particle was detected by an optimized photodetection system from 2°-162° angularly. This new progress provided a low-cost, wide-range and highly adaptive approach to measure the volume scattering function of a single particle. It also has a high potential as a methodological or instrumental foundation for the future scattering researches in the particle of non-spherical profile, complicated inner structures and anisotropic optical property.

This work,” Measurement of the light scattering of single micrometer-sized particles captured with a microfluidic trap”, has been published on the Optics Express, Optical Society of America (OSA)(2015) (Volume 23, Issue 23, pp. 29296-30582). This work was supported in part by the Natural Science Foundation of China under Grants 41276042 and 41406108.