Integrated spintrophoretic platform toward multiplexed cell tweezers (Talk)

The precise delivery of bio-functionalized matters is of great interest from the fundamental and applied viewpoints. Particularly, most existing single cell platforms are unable to achieve large scale operation with flexibility on cells and digital manipulation towards multiplex cell tweezers. Thus, there is an urgent need of innovative techniques to accomplish the automation of single cells. Recently, the flexibility of magnetic shuttling technology using nano/micro scale magnets for the manipulation of particles has gained significant advances and has been used for a wide variety of single cells manipulation tasks. Herein, let’s call “spintrophoresis” using micro-/nano-sized Spintronic devices rather than “magnetophoresis” using bulk magnet. Although a digital manipulation of single cells has been implemented by the integrated circuits of spintrophoretic patterns with current, active and passive sorting gates are required for its practical application for cell analysis. Firstly, a universal micromagnet junction for passive self-navigating gates of microrobotic carriers to deliver the cells to specific sites using a remote magnetic field is described for passive cell sorting. In the proposed concept, the nonmagnetic gap between the defined donor and acceptor micromagnets creates a crucial energy barrier to restrict particle gating. It is shown that by carefully designing the geometry of the junctions, it becomes possible to deliver multiple protein- functionalized carriers in high resolution, as well as MFC-7 and THP-1 cells from the mixture, with high fidelity and trap them in individual apartments. Secondly, a convenient approach using multifarious transit gates is proposed for active sorting of specific cells that can pass through the local energy barriers by a time-dependent pulsed magnetic field instead of multiple current wires. The multifarious transit gates including return, delay, and resistance linear gates, as well as dividing, reversed, and rectifying T-junction gates, are investigated theoretically and experimentally for the programmable manipulation of microrobotic particles. The results demonstrate that, a suitable angle of the 3D-gating field at a suitable time zone is crucial to implement digital operations at integrated multifarious transit gates along bifurcation paths to trap microrobotic carriers in specific apartments, paving the way for flexible on-chip arrays of multiplexed cells. Finally, I will include the pseudo-diamagnetic spintrophoresis using negative magnetic patterns for multiplexed magnetic tweezers without the biomarker labelling. Label free single cells manipulation, separation and localization enables a novel platform to address biologically relevant problems in bio-MEMS/ NEMS technologies.