Katzmeier Florian, Simmel Friedrich C
Department of Bioscience, TUM School of Natural Sciences, Technical University Munich, D-85748, Garching, Germany.
Nat Commun. 2023 Oct 6;14(1):6247. doi: 10.1038/s41467-023-41923-1.
Second-order electrokinetic flow around colloidal particles caused by concentration polarization electro-osmosis (CPEO) can result in a phoretic motion of asymmetric particle dimers in a homogeneous AC electrical field, which we refer to as concentration polarization electro-phoresis (CPEP). To demonstrate this actuation mechanism, we created particle dimers from micron-sized silica spheres with sizes 1.0 μm and 2.1 μm by connecting them with DNA linker molecules. The dimers can be steered along arbitrarily chosen paths within a 2D plane by controlling the orientation of the AC electric field in a fluidic chamber with the joystick of a gamepad. Further utilizing induced dipole-dipole interactions, we demonstrate that particle dimers can be used to controllably pick up monomeric particles and release them at any desired position, and also to assemble several particles into groups. Systematic experiments exploring the dependence of the dimer migration speed on the electric field strength, frequency, and buffer composition align with the theoretical framework of CPEO and provide parameter ranges for the operation of our microrobots. Furthermore, experiments with a variety of asymmetric particles, such as fragmented ceramic, borosilicate glass, acrylic glass, agarose gel, and ground coffee particles, as well as yeast cells, demonstrate that CPEP is a generic phenomenon that can be expected for all charged dielectric particles.
由浓度极化电渗（CPEO）引起的围绕胶体颗粒的二阶电动流可导致非对称颗粒二聚体在均匀交流电场中发生泳动，我们将其称为浓度极化电泳（CPEP）。为了证明这种驱动机制，我们通过用DNA连接分子将尺寸为1.0μm和2.1μm的微米级二氧化硅球连接起来，制备了颗粒二聚体。通过使用游戏手柄控制流体腔室中交流电场的方向，二聚体可以在二维平面内沿着任意选择的路径移动。进一步利用诱导偶极 - 偶极相互作用，我们证明颗粒二聚体可用于可控地拾取单体颗粒并在任何所需位置释放它们，还可将多个颗粒组装成组。探索二聚体迁移速度对电场强度、频率和缓冲液成分依赖性的系统实验与CPEO的理论框架相符，并为我们的微型机器人操作提供了参数范围。此外，对各种非对称颗粒进行的实验，如破碎的陶瓷、硼硅酸盐玻璃、丙烯酸玻璃、琼脂糖凝胶和磨碎的咖啡颗粒，以及酵母细胞，表明CPEP是一种普遍现象，所有带电介电颗粒都可能出现这种现象。
