Singh Sachin K, Rajib Md Mahadi, Drobitch Justine L, Atulasimha Jayasimha, Bandyopadhyay Supriyo, Subramanian Arunkumar
Department of Mechanical and Industrial Engineering, University of Illinois at Chicago Chicago IL 60607 USA
Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University Richmond VA 23284 USA.
RSC Adv. 2020 Oct 30;10(65):39763-39770. doi: 10.1039/d0ra08381j. eCollection 2020 Oct 27.
This report presents a three-dimensional (3-D) magnetoelectrokinetic model to investigate a new approach to magnetic-field assisted dielectrophoresis for ultra-high precision and parallel assembly of ferromagnetic Ni nanowires (NWs) on silicon chips. The underlying assembly methodology relies on a combination of electric and magnetic fields to manipulate single nanowires from a colloidal suspension and yield their assembly on top of electrodes with better than 25 nm precision. The electric fields and the resultant dielectrophoretic forces are generated through the use of patterned gold nanoelectrodes, and deliver long-range forces that attract NWs from farther regions of the workspace and bring them in proximity to the nanoelectrodes. Next, magnetic-fields generated by cobalt magnets, which are stacked on top of the gold nanoelectrodes at their center and pre-magnetized using external magnetic fields, deliver short range forces to capture the nanowires precisely on top of the nanomagnets. The 3-D NanoMagnetoElectrokinetic model, which is built using a finite element code in COMSOL software and with further computations in MATLAB, computes the trajectory and final deposition location as well as orientation for all possible starting locations of a Ni NW within the assembly workspace. The analysis reveals that magnetic-field assisted dielectrophoresis achieves ultra-high precision assembly of NWs on top of the cobalt nanomagnets from a 42% larger workspace volume as compared to pure dielectrophoresis and thereby, establishes the benefits of adding magnetic fields to the assembly workspace. Furthermore, this approach is combined with a strategy to confine the suspension within the reservoir that contains a high density of favorable NW starting locations to deliver high assembly yields for landing NWs on top of contacts that are only twice as wide as the NWs.
本报告提出了一种三维磁电动力学模型，以研究一种用于在硅芯片上对铁磁性镍纳米线（NWs）进行超高精度和平行组装的磁场辅助介电泳新方法。潜在的组装方法依赖于电场和磁场的组合，以从胶体悬浮液中操纵单个纳米线，并使其在电极顶部以优于25纳米的精度进行组装。电场和由此产生的介电泳力是通过使用图案化的金纳米电极产生的，这些电极提供远程力，从工作空间的更远区域吸引纳米线，并将它们带到纳米电极附近。接下来，由钴磁体产生的磁场，这些钴磁体堆叠在金纳米电极中心的顶部，并使用外部磁场进行预磁化，提供短程力，将纳米线精确捕获在纳米磁体顶部。使用COMSOL软件中的有限元代码构建并在MATLAB中进行进一步计算的三维纳米磁电动力学模型，计算了镍纳米线在组装工作空间内所有可能起始位置的轨迹、最终沉积位置以及方向。分析表明，与纯介电泳相比，磁场辅助介电泳在钴纳米磁体顶部实现了纳米线的超高精度组装，其工作空间体积大42%，从而确立了在组装工作空间中添加磁场的好处。此外，这种方法与一种将悬浮液限制在储液器内的策略相结合，该储液器包含高密度的有利纳米线起始位置，以便在宽度仅为纳米线两倍的触点顶部实现纳米线着陆的高组装产率。
