An integrated microfluidic cell for detection, manipulation, and sorting of single micron-sized magnetic beads

A lab-on-a-chip integrated microfluidic cell has been developed for magnetic biosensing, which is comprised of anisotropic magnetoresistance (AMR) sensors optimized for the detection of single magnetic beads and electrodes to manipulate and sort the beads, integrated into a microfluidic channel. The device is designed to read out the real-time signal from 9 mu m diameter magnetic beads moving over AMR sensors patterned into 18x4.5 mu m rectangles and 10 mu m diameter rings and arranged in Wheatstone bridges. The beads are moved over the sensors along a 75x75 mu m wide channel patterned in SU8. Beads of different magnetic moments can be sorted through a magnetostatic sorting gate into different branches of the microfluidic channel using a magnetic field gradient applied by lithographically defined 120 nm thick Cu striplines carrying 0.2 A current. (C) 2006 American Institute of Physics.