Large-area GMR bio-sensors based on reverse nucleation switching mechanism.

Highlights • The sensitivity of stripe-shaped GMR biosensors is limited. • Biological detection in large-area sensors is realized by the reverse nucleation sites under MNPs. • Large-area sensors exhibit better linearity 20 times higher sensitivity. Abstract In the past 20 years, several studies have been performed on the detection of biomarkers by the stripe-shaped spin valve sensors, whose sensitivity is limited by their small sensing area and large sensor resistance. In this paper, large-area spin valve sensors with lower aspect ratio are introduced. A reverse nucleation mechanism is proposed to demonstrate the different switching processes in large-area sensors. The simulation results further prove the involvement of reverse nucleation sites during the magnetization reversal. Large-area sensors also exhibit a linear response to the concentration of magnetic nanoparticles with a sensor signal more than 20 times larger than the stripe sensors. [ABSTRACT FROM AUTHOR]