Abstract
Intense research is presently directed toward the development of high sensitivity biosensors for the detection of magnetic beads in biochemical applications. In this study, we detected magnetic cells and ferrofluid detection by performing a magnetoresistance-based experiment using a permalloy thin film on a wave sheet. The magnetoresistance curves show switching field or full width half maximum is altered during the magnetization. When magnetic cells or ferrofluid are on the permalloy thin film, the switching field or full width half maximum is increased due to the added magnetic stray field from the superparamagnetic beads. Comparing with the thin film on flat surface, the thin film on wave sheet with Z-direction magnetic field is the most sensitive for detection of magnetic cells and ferrofluid. This scheme can be applied to the bioassay utilized cells detection with magnetic particles entered by endocytosis. The high potential of the sensor will impact on biochemical applications and diagnosis in medicine.