Wave-Like Pseudo-Spin Valve Thin Film as a Biosensor

A magnetic biosensor using an anisotropic magnetoresistance effect based on a wave-like pseudo-spin valve is proposed. The wave-like structure formed trenches for attaching cells, which contain Fe₃O₄ magnetic nanoparticles by endocytosis, and subsequently altered the magnetic properties of pseudo-spin valve (10 nm Ti/8 nm CoFe/[4 nm Cu/4 nm CoFe]4/[4 nm Cu/8 nm CoFe]4/10 nm Ti). We measured the magnetic hysteresis loops via vibrating sample magnetometer (VSM) in three orthogonal directions. It was observed that devices with attaching cells show significant increases of the switching fields compared to the case without attaching cells when the external magnetic field is in parallel to the elongated trenches, considering an easy axis.