ABSTRACT
Methods known as micro total analysis systems (μTASs) or labs-on-a-chip (LOCs) rely on the technology of micro-electro-mechanical systems (MEMS) to down-scale chemical and biomedical analysis of samples on a small integrated system. Magnetic separation in μTAS, LOC or bioMEMS is one of many useful applications of magnetic nanoparticles. Magnetic nanoparticles under a magnetic field experience a magnetic force and work as a carrier to separate or sort biological samples. Integrated micro-analytical systems enable precise spatial and temporal control of magnetic fields, allowing for efficient manipulation of targets, including proteins, bacteria, viruses, DNA/RNA and cells, which play key roles in clinical studies.
In this chapter, we review the principles, materials and applications of magnetic separation in integrated micro-analytical systems. We describe the magnetization of materials and forces used in separation and review the types of magnets and magnetic particles. The methods of device integration, especially for the design and fabrication of microscale magnets in microfluidic systems, are explained in detail and followed by the review of their clinical applications. We focus on the techniques to separate rare cells, including circulating tumour cells and stem cells, to discuss challenges and promising applications of this approach.
