Patterning a wide range of colloidal plasmonic nanoparticles into prescribed spatial arrangements, analogous to the formation of natural materials, enables the fabrication of functionalized structures with novel optical properties, such as Fano resonance, magneto-optical Kerr effect, negative refraction, etc. Currently, capillarity-assisted particle assembly is always utilized to place colloidal particles at predetermined positions by exploiting the capillary forces resulting from the motion of an evaporating droplet. However, this technique requires specialized equipment and the assembly process is always carried out in an open system, thereby introducing the risk of contamination and limiting its applications. Here, we present a microfluidic and magnetic field-assisted self-assembly of colloidal magnetic-plasmonic nanoparticles by utilizing magnetic dipole–dipole interactions resulting from the localized magnetic gradient field produced by an array of soft-magnetic elements and external magnetic bias field. The magnetized magnetic-plasmonic nanoparticles are controlled to deposit at the predesigned traps microfabricated onto the soft-magnetic elements. After deposition, the inlet velocity of the microchannel is improved to clear away the particles out of the traps, forming arrays of patterns with consistent structures. Furthermore, a Lagrangian–Eulerian model is introduced for the first time to predict the processing of the microfluidic and magnetic field-assisted self-assembly of colloidal magnetic-plasmonic nanoparticles by taking the magnetic and hydrodynamic forces and particle–fluid interaction into account. Our analysis demonstrates that the particle–fluid interaction not only plays a significant role in determining the final self-assembled nanostructures, but provides an opportunity to improve the consistency of the assembled nanostructures. The microfluidic and magnetic field-assisted self-assembly protocol proposed here enables the patterning of colloidal magnetic-plasmonic nanoparticles to be carried out in a controlled environment and also opens up a new direction for assembling complex structures.

将各种胶体等离子体纳米粒子图案化成规定的空间排列，类似于天然材料的形成，能够制造具有新光学特性的功能化结构，例如 Fano 共振、磁光克尔效应、负折射等。 目前，毛细作用辅助粒子组装总是用于通过利用蒸发液滴运动产生的毛细管力将胶体粒子放置在预定位置。然而，这种技术需要专门的设备，并且组装过程总是在开放系统中进行，从而引入了污染风险并限制了其应用。这里，我们通过利用由软磁元件阵列和外部磁偏置场产生的局部磁梯度场产生的磁偶极 - 偶极相互作用，提出了胶体磁等离子体纳米粒子的微流体和磁场辅助自组装。磁化的磁等离子体纳米粒子被控制在预先设计的陷阱处沉积，微制造到软磁元件上。沉积后，提高微通道的入口速度以清除陷阱中的颗粒，形成具有一致结构的图案阵列。此外，首次引入拉格朗日-欧拉模型，通过考虑磁力和流体动力以及颗粒-流体相互作用来预测胶体磁-等离子体纳米颗粒的微流体和磁场辅助自组装的过程。我们的分析表明，粒子-流体相互作用不仅在确定最终的自组装纳米结构中起着重要作用，而且还提供了提高组装纳米结构一致性的机会。这里提出的微流体和磁场辅助自组装协议使胶体磁等离子体纳米粒子的图案化能够在受控环境中进行，也为组装复杂结构开辟了新的方向。我们的分析表明，粒子-流体相互作用不仅在确定最终的自组装纳米结构中起着重要作用，而且还提供了提高组装纳米结构一致性的机会。这里提出的微流体和磁场辅助自组装协议使胶体磁等离子体纳米粒子的图案化能够在受控环境中进行，也为组装复杂结构开辟了新的方向。我们的分析表明，粒子-流体相互作用不仅在确定最终的自组装纳米结构方面发挥着重要作用，而且为提高组装纳米结构的一致性提供了机会。这里提出的微流体和磁场辅助自组装协议使胶体磁等离子体纳米粒子的图案化能够在受控环境中进行，也为组装复杂结构开辟了新的方向。