NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Roma, I-00185, Italy.
Physics Department, University of Rome "Sapienza", Roma, I-00185, Italy.
Sci Rep. 2020 Mar 12;10(1):4609. doi: 10.1038/s41598-020-61451-y.
We combine two-photon lithography and optical tweezers to investigate the Brownian fluctuations and propeller characteristics of a microfabricated helix. From the analysis of mean squared displacements and time correlation functions we recover the components of the full mobility tensor. We find that Brownian motion displays correlations between angular and translational fluctuations from which we can directly measure the hydrodynamic coupling coefficient that is responsible for thrust generation. By varying the distance of the microhelices from a no-slip boundary we can systematically measure the effects of a nearby wall on the resistance matrix. Our results indicate that a rotated helix moves faster when a nearby no-slip boundary is present, providing a quantitative insight on thrust enhancement in confined geometries for both synthetic and biological microswimmers.
我们结合双光子光刻和光镊来研究微加工螺旋的布朗涨落和螺旋桨特性。通过分析均方位移和时间相关函数，我们恢复了完整迁移张量的分量。我们发现，布朗运动显示出角和平移涨落之间的相关性，我们可以直接测量产生推力的流体动力耦合系数。通过改变微螺旋与无滑移边界的距离，我们可以系统地测量近壁面效应对阻力矩阵的影响。我们的结果表明，当存在近邻无滑移边界时，旋转螺旋的运动速度更快，这为受限几何形状中合成和生物微游泳者的推力增强提供了定量的见解。
