Dept. of Mechanical Engineering, Hanyang University, Seoul, 04763, Korea.
Insitute of Nano Science and Technology, Hanyang University, Seoul, 04763, Korea.
Sci Rep. 2017 Jun 8;7(1):3062. doi: 10.1038/s41598-017-03028-w.
Droplet control through the use of light-induced thermocapillary effects has recently garnered attention due to its non-intrusive and multifunctional nature. An important issue in droplet control is the estimation of the thermocapillary force. The purpose of the present study is to estimate the thermocapillary force and propose empirical equations between the force and simply measurable key parameters such as droplet diameter and power of heat source. In addition, we aim to shift the droplet trajectory and develop an on-demand droplet routing system based on the estimation of the thermocapillary force. We illuminated a continuous phase with a 532 nm laser beam to minimize possible damage or property changes to target molecules contained within droplets. A mixture of light-absorbing material and oleic acid was used for the continuous phase fluid, while deionized water (DI water) was used for the dispersed phase fluid. We proposed empirical equations to estimate the thermocapillary force, which was then applied to precise droplet shifting and routing. We found that the shifting distance was linearly proportional to the thermocapillary force, and that an on-demand droplet routing system resulted in a success rate greater than 95%.
由于光致热毛细效应的非侵入性和多功能性，通过该效应控制液滴最近受到了关注。在液滴控制中，一个重要的问题是热毛细力的估计。本研究的目的是估计热毛细力，并提出力与简单可测量的关键参数（如液滴直径和热源功率）之间的经验方程。此外，我们旨在根据热毛细力的估计来改变液滴轨迹并开发按需液滴路由系统。我们用 532nm 激光束照射连续相，以最小化可能对液滴中包含的目标分子造成的损害或性质变化。连续相流体使用了光吸收材料和油酸的混合物，而分散相流体则使用去离子水（DI 水）。我们提出了经验方程来估计热毛细力，然后将其应用于精确的液滴移动和路由。我们发现，移动距离与热毛细力成正比，并且按需液滴路由系统的成功率大于 95%。
