Max Bergmann Center of Biomaterials and Institute for Materials Science, Technische Universität Dresden, 01062, Dresden, Germany.
Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research, Bautzner Landstrasse 400, 01328, Dresden, Germany.
Eur Phys J E Soft Matter. 2021 Mar 23;44(3):39. doi: 10.1140/epje/s10189-021-00008-x.
Control over micromotors' motion is of high relevance for lab-on-a-chip and biomedical engineering, wherein such particles encounter complex microenvironments. Here, we introduce an efficient way to influence Janus micromotors' direction of motion and speed by modifying their surface properties and those of their immediate surroundings. We fabricated light-responsive Janus micromotors with positive and negative surface charge, both driven by ionic self-diffusiophoresis. These were used to observe direction-of-motion reversal in proximity to glass substrates for which we varied the surface charge. Quantitative analysis allowed us to extract the dependence of the particle velocity on the surface charge density of the substrate. This constitutes the first quantitative demonstration of the substrate's surface charge on the motility of the light-activated diffusiophoretic motors in water. We provide qualitative understanding of these observations in terms of osmotic flow along the substrate generated through the ions released by the propulsion mechanism. Our results constitute a crucial step in moving toward practical application of self-phoretic artificial micromotors.
对微马达运动的控制对于芯片实验室和生物医学工程具有重要意义，因为这些粒子会遇到复杂的微环境。在这里，我们介绍了一种通过改变微马达表面特性及其周围环境来影响 Janus 微马达运动方向和速度的有效方法。我们制造了具有正、负表面电荷的光响应 Janus 微马达，它们都由离子自扩散泳驱动。我们利用这些微马达来观察在靠近玻璃基底时的运动方向反转，而我们可以改变基底的表面电荷。定量分析使我们能够提取出粒子速度与基底表面电荷密度的依赖关系。这是首次在水中用光激活扩散泳马达定量证明基底表面电荷对运动的影响。我们根据推进机制释放的离子产生的沿基底的渗透压流，从定性角度理解了这些观察结果。我们的结果是朝着实用的自泳人工微马达应用迈出的关键一步。
