Electropermanent magnet actuation for droplet ferromicrofluidics
A team of researchers from Stanford University, Stanford, California have demonstrated magnetic actuation of microfluidic water droplets using miniature EPMs and oil-based ferrofluids. Water droplets, immersed in a continuous oil ferrofluid phase, experience a repulsive magnetophoretic force in the presence of an inhomogeneous magnetic field. EPMs, capable of generating strong magnetic fields and gradients, are used for the first time in microfluidic applications. Magnetic actuation is an attractive approach to microfluidic manipulation, given that strong magnetic fields can be applied on biological materials or fluids with negligible physiological impact. Despite its common use in passive microfluidic systems, there's been limited development of active magnetic actuation methods, mainly due to the limitations of conventional electromagnetic sources. EPMs combine the switching capability of electromagnets with the strength of permanent magnets in a compact package. In this work, Stanford researchers designed, fabricated and integrated EPMs with PDMS microfluidic chips. Using fast EPM activation...