Highly sensitive spin‐valve devices for chip‐cytometers

The highly sensitive spin‐valve devices integrated with a microfluidic channel have been studied for cell counting in a chip‐cytometer. The presence or absence of a single magnetic bead was successfully detected by direct measurement of fringe fields emanating from magnetic beads using spin‐valve devices. The real‐time detection was also successfully confirmed by the direct measurement of magnetic fields generated from the magnetic beads passing an active sensing area of a spin‐valve device integrated with a microfluidic channel. Our results show the possibility of implementing a chip‐cytometer for biological applications using the highly sensitive spin‐valve devices integrated with a microfluidic device. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)