Affiliation:
1. Huazhong University of Science and Technology
2. The Chinese University of Hong Kong
Abstract
Optical tweezers (OTs) can immobilize and manipulate objects with sizes that span between nano- and micro-meter scales. The manipulating ability of OTs is traditionally characterized by stability factor (S), which can only indicate an empirical “hit-or-miss” process. Additionally, the current quantitative models for trapping stability rarely consider the influence of external flow. In this paper, a comprehensive analysis to quantify the optical trapping stability in a perturbed asymmetric potential well is presented from the perspective of statistics, especially for weak trapping scenarios. Our analytical formulation takes experimentally measurable parameters including particle size, optical power, and spot width as inputs and precisely outputs a statistically relevant mean trapping time. Importantly, this formulation takes into account general and realistic cases including fluidic flow velocity and other perturbations. To verify the model, a back-focal-plane-interferometer-monitored trapping experiment in a flow is set up and the statistical characteristics of trapping time demonstrate good agreement with theoretical predictions. In total, the model quantitatively reveals the effects of external disturbance on trapping time, which will find applications where optical trapping stability is challenged by external perturbations in weak trapping conditions.
Funder
National Natural Science Foundation of China
Social Development Project of Jiangsu Province
Key Technology Research and Development Program of Shandong Province
Innovation Fund of Wuhan National Laboratory for Optoelectronics
1000 Talent Youth Program
General Research Fund from Research Grants Council of HKSAR