Planar Hall Effect in Spin Valve Structure for DNA Detection Immobilized with Single Magnetic Bead

There is a considerable effort directed towards understanding and negating the proliferation of infectious diseases by improving the sensitivity of biosensors. We describe the investigation of nucleic acid interactions based on immobilization of thiolated probe DNA followed by the coupling of biotinylated DNA and streptavidin coated Dyna beads on the gold film deposited on the substrate for the further application with the Planar Hall effect in spin valve structure of Ta/NiFe/Cu/NiFe/IrMn/Ta which has been applied to single magnetic bead detection sensor with the size of 3x3 mu m(2). The spin valve structure which incorporates free and pinned layers was used as magnetic field sensor based on the resistance changes when the magnetization orientation in free magnetic layer rotates to the change of external applied magnetic field. It is demonstrated to induce a high sensitivity due to small interlayer coupling between free and pinned layers, and improved signal-to-noise due to very thin active sensing layer; compared to the other structures.. In the results, the sensor performance with single Dynabeads (R) M-280 Streptavidin conjugated with target DNA and probe DNA was reported as a significantly sensitive system with high signals of around 1.4 mu V. These, therefore, can be used well for biomolecule recognition, biotechnology and biosensor application.