Wavy ferromagnetic device as single cell detection

Abstract

We demonstrate a design of using a wavy permalloy thin film as a cell sensing device for the purpose of single magnetic cell detection. The magnetoresistance curve (MR curve) differs according to the single magnetic cell attached to the surface. By analyzing the MR curves, we can determine the sensing capability of the permalloy magnetic film device. Our results indicate that the sensitivity of the permalloy film sensing devices with wavy surface is much higher than the devices with flat surface. When a single magnetic cell is captured by the wavy surface of the permalloy film, the switching field of the film increase which is caused by the stray field of the magnetic cell. We discover that the highest sensitivity occurs when the direction of the magnetic field is along the Z-axis, and there is significant potential for the application of cell detection.

Tunable Perpendicular Magnetoresistive Sensor Driven by Shape and Substrate Induced Magnetic Anisotropy

“…[8] In particular, permalloy nanowires and films grown on specially patterned groove-substrates appear as a very powerful technique for single cell detection showing the highest sensitivity for out-of-plane magnetic fields. [13,14] Here, we investigate anisotropic magnetoresistance effects on a series of permalloy strips of different widths and thicknesses for applied magnetic fields perpendicular to the strip plane. Sharp anomalous peaks in the magnetoresistance curves are observed, indicative of an abrupt magnetization reversal mechanism.…”