Liang Jiayun, Al Balushi Zakaria Y
Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California94720, United States.
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States.
ACS Appl Mater Interfaces. 2023 Feb 2;15(7):10182-92. doi: 10.1021/acsami.2c20116.
Achieving control over the motion of dissolved particles in liquid metals is of importance for the meticulous realization of hierarchical particle assemblies in a variety of nanofabrication processes. Brownian forces can impede the motion of such particles, impacting the degree of perfection that can be realized in assembled structures. Here, we show that light-induced Marangoni flow in liquid metals (i.e., liquid-gallium) with Laguerre-Gaussian (LG) lasers as heating sources is an effective approach to overcome Brownian forces on particles, giving rise to predictable assemblies with a high degree of order. We show that by carefully engineering surface tension gradients in liquid-gallium using non-Gaussian LG lasers, the Marangoni and convective flow that develops in the fluid drives the trajectory of randomly dispersed particles to assemble into 100 μm wide ring-shaped particle assemblies. Careful control over the parameters of the LG laser (i.e., laser mode, spot size, and intensity of the electric field) can tune the temperature and fluid dynamics of the liquid-gallium as well as the balance of forces on the particle. This in turn can tune the structure of the ring-shaped particle assembly with a high degree of fidelity. The use of light to control the motion of particles in liquid metals represents a tunable and rapidly reconfigurable approach to spatially design surface tension gradients in fluids for more complex assembly of particles and small-scale solutes. This work can be extended to a variety of liquid metals, complementary to what has been realized in particle assembly out of ferrofluids using magnetic fields.
在各种纳米制造工艺中，实现对液态金属中溶解粒子运动的控制对于精确实现分层粒子组装至关重要。布朗力会阻碍此类粒子的运动，影响组装结构所能达到的完美程度。在此，我们表明，以拉盖尔 - 高斯（LG）激光作为热源，在液态金属（即液态镓）中产生的光致马兰戈尼流是克服粒子上布朗力的有效方法，可形成具有高度有序性的可预测组装结构。我们表明，通过使用非高斯LG激光精心设计液态镓中的表面张力梯度，流体中产生的马兰戈尼流和对流会驱动随机分散粒子的轨迹，使其组装成宽度为100μm的环形粒子组件。仔细控制LG激光的参数（即激光模式、光斑尺寸和电场强度）可以调节液态镓的温度和流体动力学以及粒子上的力平衡。这进而可以高度精确地调节环形粒子组件的结构。利用光来控制液态金属中粒子的运动代表了一种可调节且能快速重新配置的方法，用于在空间上设计流体中的表面张力梯度，以实现更复杂的粒子和小尺度溶质组装。这项工作可以扩展到多种液态金属，与利用磁场在铁磁流体中实现的粒子组装互为补充。
