Nalupurackal Gokul, Gunaseelan M, Roy Srestha, Lokesh Muruga, Kumar Sumeet, Vaippully Rahul, Singh Rajesh, Roy Basudev
Department of Physics, Quantum Centres in Diamond and Emergent Materials (QuCenDiEM)-group, Micro Nano and Bio-Fluidics (MNBF)-Group, IIT Madras, Chennai 600036, India.
Department of Physics, IIT Madras, Chennai 600036, India.
Soft Matter. 2022 Sep 21;18(36):6825-6835. doi: 10.1039/d2sm00627h.
Optical tweezers have revolutionised micromanipulation from physics and biology to material science. However, the high laser power involved in optical trapping can damage biological samples. In this context, indirect trapping of microparticles and objects using fluid flow fields has assumed great importance. It has recently been shown that cells and particles can be turned in the pitch sense by opto-plasmonic heating of a gold surface constituting one side of a sample chamber. We extend that work to place two such hotspots in close proximity to each other to form a very unique configuration of flow fields forming an effective quasi-three-dimensional 'trap', assisted by thermophoresis. This is effectively a harmonic trap confining particles in all three dimensions without relying on other factors to confine the particles close to the surface. We use this to show indirect trapping of different types of upconverting particles and cells, and also show that we can approach a trap stiffness of 40 fN μm indicating a weak confinement regime without relying on feedback.
光镊已经彻底改变了从物理、生物到材料科学的微操纵技术。然而，光阱中涉及的高激光功率会损坏生物样品。在这种情况下，利用流体流场间接捕获微粒和物体变得极为重要。最近的研究表明，通过对构成样品腔一侧的金表面进行光热等离子体加热，可以使细胞和微粒在俯仰方向上转动。我们将这项工作进行了扩展，将两个这样的热点彼此靠近放置，以形成一种非常独特的流场配置，借助热泳形成一个有效的准三维“陷阱”。这实际上是一个谐波陷阱，能在所有三个维度上限制粒子，而无需依赖其他因素将粒子限制在靠近表面的位置。我们利用这一点展示了对不同类型的上转换粒子和细胞的间接捕获，并且还表明，在不依赖反馈的情况下，我们能够达到40 fN/μm的陷阱刚度，这表明处于弱限制状态。
