标题： 电解梯度方向对死端孔中泳动传输的影响 显示英文标题

标题： On the influence of electrolytic gradient orientation on phoretic transport in dead-end pores

摘要： 电解电渗扩散迁移是指由于局部电解质浓度（$c$）梯度而产生的界面力导致胶体的定向迁移。 这种物理化学传输在许多微尺度应用中提供了一种高效的替代方法，其中对流引起的传输不可行。 在死端孔中的电渗抽吸和注入可以通过将盐浓度梯度定向进入或离开孔来控制；然而，这种定向对时空传输模式的影响程度尚未得到充分探讨。 在本研究中，我们发现它有显著影响：溶质向外模式（$\beta=c_\infty/c_{\text{pore}}<1$）的胶体抽吸更快且更浅，而溶质向内模式则能实现更深的抽吸。 同样，溶质向外注入具有快速传播的波前，而溶质向内模式（$\beta >1$）则促进均匀且渐进的注入。 每种模式的传输被发现会在不同的时间尺度上演化并持续存在。 我们表征了这些模式的性能，并发现尽管溶质向外模式的持续性随着电解质梯度的增大而增强（$\sim \ln(\beta^{-0.4})$），但溶质向内模式则减弱，并最终其持续性对$\beta$不敏感。 我们还引入了可变迁移率模型来研究大ζ电位的影响，这进一步增强了溶质向外模式的传输并削弱了溶质向内模式。 此外，我们研究了两种模式的渗透流如何影响注入和抽吸模式。 我们发现渗透引起的混合可以出人意料地抑制溶质向外模式中的注入效果。 这些见解引起了对不同电渗传输模式之间差异的关注，并有助于在众多微尺度应用中合理设计和设置电解质梯度。 显示英文摘要

摘要： Electrolytic diffusiophoresis refers to directional migration of colloids due to interfacial forces that develop in response to local electrolytic concentration ($c$) gradients. This physicochemical transport provides an efficient alternative in numerous microscale applications where advection-induced transport is infeasible. Phoretic withdrawal and injection in dead-end pores can be controlled by orienting salt gradients into or out of the pore; however, the extent to which this orientation influences spatiotemporal transport patterns is not thoroughly explored. In this study, we find that it has a significant influence: colloidal withdrawal in solute-out mode ($\beta=c_\infty/c_{\text{pore}}<1$) is faster and shallower, whereas the solute-in mode enables deeper withdrawal. Similarly, solute-out injection features rapidly propagating wavefronts, whereas the solute-in mode ($\beta >1$) promotes uniform and gradual injection. Each mode's transport is found to evolve and persist over different time scales. We characterize the performance of these modes and find that while persistence of the solute-out mode strengthens with a growing electrolytic gradient [$\sim \ln(\beta^{-0.4})$], solute-in mode diminishes and eventually its persistence is insensitive to $\beta$. We also incorporate the variable mobility model to examine the impact of large zeta potentials, which intensifies the transport of solute-out mode further and weakens the solute-in mode. Additionally, we investigate how osmotic flows of the two modes affect injection and withdrawal patterns. We find that osmosis-induced mixing can counterintuitively inhibit injection effectiveness in solute-out mode. These insights bring attention to the distinctions between different phoretic transport modes and contribute to the rational design and setup of electrolytic gradients in numerous microscale applications.