The Study on a High Sensitivity as Planar Hall Biosensor by using the NiFe/Ta(t)/NiFe Film

As a device that measures a fine magnetic field to be used as a biosensor, a simple multilayered cross-shaped current and voltage terminals are formed. The sensitivity of planar Hall voltage sensitivity (SPHV) were obtained from the planar Hall voltage (PHV) curve, which was measured by applying an external magnetic field perpendicular to the magnetization easy axis. The PHV curve for the NiFe(6 nm)/Ta(20 nm)/NiFe(6 nm) multilayer changed linearly in the region of +/- 0.9 Oe, and the SPHV was 500 mu V/Oe. In particular, as the increased sensing current from 1.0 mA to 40 mA, the SPHV was from 2.0 mV/Oe to 398 mu V/Oe. These results suggested the possibility of developing a PHR biosensor with high sensitivity even with a multilayer structure formed of a bottom Ta layer and a ferromagnetic NiFe layer.