Masterclass : magnetic particles in motion for biosensing

The aging population and increases in chronic diseases put high pressure on the healthcare system and drive a need for easy to use and cost-effective medical technologies. In-vitro diagnostics (IVD) plays a large role in delivering healthcare and within the IVD market, decentralized diagnostic testing, i.e. point-of-care testing (POCT), is a growing segment. POCT devices should be compact and fully integrated for maximum ease of use. A new class of POCT devices is appearing based on the use of actuated magnetic particles. The use of magnetic particles has important advantages: they have a large surface-to-volume ratio, are conveniently bio-functionalized, provide a large optical contrast, and they can be manipulated by magnetic fields for full control of the integrated biosensing assay. In this lecture, I will review the use of magnetic particles actuated by magnetic fields to realize integrated lab-on-chip diagnostic devices wherein several assay process steps are combined, e.g. to mix fluids, capture analytes, concentrate analytes, transfer analytes, label analytes, and perform stringency and washing steps. I will focus on realizations within the concept of stationary microfluidics, in which fluid manipulation is minimized and the assay steps are essentially effectuated by magnetic particles and magnetic forces. I will discuss efforts to combine and integrate different magnetically actuated assay steps, with the vision that it will become possible in the future to realize integrated, cost-effective and easy to use stationary-fluidic biosensing systems in which all assay process steps are controlled and optimized by magnetic forces.