Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, P. R. China.
Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 266101, Qingdao, P. R. China.
Nat Commun. 2021 Dec 8;12(1):7136. doi: 10.1038/s41467-021-27503-1.
Flexible actuation of droplets is crucial for biomedical and industrial applications. Hence, various approaches using optical, electrical, and magnetic forces have been exploited to actuate droplets. For broad applicability, an ideal approach should be programmable and be able to actuate droplets of arbitrary size and composition. Here we present an "additive-free" magnetic actuation method to programmably manipulate droplets of water, organic, and biological fluids of arbitrary composition, as well as solid samples, on a ferrofluid-infused porous surface. We specifically exploit the spontaneously formed ferrofluid wetting ridges to actuate droplets using spatially varying magnetic fields. We demonstrate programmed processing and analysis of biological samples in individual drops as well as the collective actuation of large ensembles of micrometer-sized droplets. Such model respiratory droplets can be accumulated for improved quantitative and sensitive bioanalysis - an otherwise prohibitively difficult task that may be useful in tracking coronavirus.
液滴的灵活驱动对于生物医学和工业应用至关重要。因此，人们利用光学、电学和磁场等各种方法来驱动液滴。为了广泛适用，理想的方法应该是可编程的，并且能够驱动任意大小和组成的液滴。在这里，我们提出了一种“无添加剂”的磁驱动方法，可在铁磁流体注入的多孔表面上对任意组成的水、有机和生物流体以及固体样品的液滴进行可编程操控。我们特别利用自发形成的铁磁流体润湿脊，通过空间变化的磁场来驱动液滴。我们演示了在单个液滴中对生物样品进行编程处理和分析，以及对大规模微米级液滴进行集体驱动。这样的模型呼吸液滴可以被聚集起来，以进行改进的定量和敏感的生物分析——这是一项非常困难的任务，在追踪冠状病毒方面可能会很有用。
