Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Am Muehlenberg 1, 14476, Potsdam, Germany.
Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Muehlenberg 1, 14476, Potsdam, Germany.
Nat Commun. 2022 May 10;13(1):2562. doi: 10.1038/s41467-022-30229-3.
We report, for the first time, a chemotactic motion of emulsion droplets that can be controllably and reversibly altered. Our approach is based on using biphasic Janus emulsion droplets, where each phase responds differently to chemically induced interfacial tension gradients. By permanently breaking the symmetry of the droplets' geometry and composition, externally evoked gradients in surfactant concentration or effectiveness induce anisotropic Marangoni-type fluid flows adjacent to each of the two different exposed interfaces. Regulation of the competitive fluid convections then enables a controllable alteration of the speed and the direction of the droplets' chemotactic motion. Our findings provide insight into how compositional anisotropy can affect the chemotactic behavior of purely liquid-based microswimmers. This has implications for the design of smart and adaptive soft microrobots that can autonomously regulate their response to changes in their chemical environment by chemotactically moving towards or away from a certain target, such as a bacterium.
我们首次报告了乳液液滴的趋化运动，这种运动可以被可控且可逆地改变。我们的方法基于使用双相 Janus 乳液液滴，其中每个相对化学诱导的界面张力梯度的响应不同。通过永久打破液滴几何形状和组成的对称性，外部引发的表面活性剂浓度或效力的梯度会在两个不同暴露界面的每一个旁边引起各向异性的 Marangoni 型流体流动。然后，对竞争流体对流的调节使得液滴趋化运动的速度和方向能够可控地改变。我们的发现深入了解了组成各向异性如何影响纯基于液体的微游泳者的趋化行为。这对于设计智能和自适应软微机器人具有重要意义，这些机器人可以通过趋化性地朝向或远离特定目标（例如细菌）来自动调节其对化学环境变化的响应。
