Microbeads detection using Planar Hall effect in spin-valve structure

Abstract

The Planar Hall effect in a spin-valve structure of Ta/NiFe/CoFe/Cu/CoFe/IrMn/Ta has been applied as a biosensor being capable of detecting Dynabeads((R)) M-280. The patterns with a size of 50 x 100 mu m(2) were prepared by lithography methods, and the biosensor performance was tested under the application of a DC magnetic field where the output signals were obtained from a nanovoltmeter. The sensor signal has produced high sensitivity results; especially, the real-time profiles revealed stable and significant signals at external applied magnetic field of around 7.0 Oe with the resolution of 0.04 beads per mu m(2). With these results, it could be feasible to detect some commercial Dynabeads((R)) M-280 which can be used for recognition force and biomolecular interaction measurements. (c) 2007 Elsevier B.V. All rights reserved.