Opto-thermoelectric microswimmers
Opto-thermoelectric microswimmers
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DOI：
10.1038/s41377-020-00378-5
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发表时间：
2020-08-17
影响因子：
19.4
通讯作者：
Zheng, Yuebing
中科院分区：
文献类型：
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作者：
Peng, Xiaolei;Chen, Zhihan;Zheng, Yuebing
由光推动的介电金属微结构可以在流体中游动和导航。来自美国德克萨斯大学和中国北京清华大学的彭小雷和他的同事们制作了一种聚苯乙烯微粒，这种微粒半包裹着金，悬浮在0.2毫米十六烷基三乙基氯化铵（CTAC）的水溶液中。当用散焦激光束照射时，不对称的光吸收和加热导致温度梯度和光热电场，该光热电场推动微粒向温度梯度方向运动。在1064nm波长、低光强0.03 mW/ μ m的激光束照射下，2.1 μ m大小的粒子的游动速度可达近20 μ m/s(2)。使用第二束聚焦激光束可以使微粒子旋转，从而控制运动方向。受大肠杆菌（E. coli）细胞“奔跑和翻滚”行为的启发，我们开发了光热电微游泳者。微游泳者基于介电- au Janus粒子，由粒子的不对称光热响应产生的自持续电场驱动。在散焦激光束的照射下，Janus粒子沿着粒子表面呈现出光学产生的温度梯度，导致光热电场推动粒子。我们进一步发现，游动方向是由粒子的取向决定的。为了使游泳者能够导航，我们提出了一种新的光力学方法，利用聚焦激光束在温度梯度感应电场下驱动Janus粒子的平面内旋转。定时旋转激光束使我们能够将粒子定位在任何期望的方向，从而有效地主动控制游泳方向。通过将暗场光学成像与反馈控制算法相结合，实现了微游泳器的自动推进和导航。我们的光热电微游泳器可以在动态胶体系统、活性物质、生物医学传感和靶向药物递送的光热电耦合研究中找到应用。
Optical actuation: microparticle swimming Dielectric-metal microstructures that are propelled by light can swim and navigate in fluids. Xiaolei Peng and coworkers from the University of Texas, US and Tsinghua University in Beijing, China, fabricated polystyrene microparticles that were half-coated with gold and suspended in a solution of water and 0.2 mM of cetyltrimenthylammonium chloride (CTAC). When illuminated with a defocused laser beam, asymmetric optical absorption and heating leads to a temperature gradient and an opto-thermoelectric field that propels the microparticles in the direction of the temperature gradient. Swimming velocities of up to nearly 20 mu m/s were measured for 2.1 mu m-sized particles illuminated with a 1064nm-wavelength laser beam with a low optical intensity of 0.03 mW/mu m(2). The use of a second focused laser beam makes it possible to rotate the microparticles and thus control the direction of motion.Inspired by the "run-and-tumble" behaviours of Escherichia coli (E. coli) cells, we develop opto-thermoelectric microswimmers. The microswimmers are based on dielectric-Au Janus particles driven by a self-sustained electrical field that arises from the asymmetric optothermal response of the particles. Upon illumination by a defocused laser beam, the Janus particles exhibit an optically generated temperature gradient along the particle surfaces, leading to an opto-thermoelectrical field that propels the particles. We further discover that the swimming direction is determined by the particle orientation. To enable navigation of the swimmers, we propose a new optomechanical approach to drive the in-plane rotation of Janus particles under a temperature-gradient-induced electrical field using a focused laser beam. Timing the rotation laser beam allows us to position the particles at any desired orientation and thus to actively control the swimming direction with high efficiency. By incorporating dark-field optical imaging and a feedback control algorithm, we achieve automated propelling and navigation of the microswimmers. Our opto-thermoelectric microswimmers could find applications in the study of opto-thermoelectrical coupling in dynamic colloidal systems, active matter, biomedical sensing, and targeted drug delivery.