High-sensitivity planar Hall sensor based on simple gaint magneto resistance NiFe/Cu/NiFe structure for biochip application
Dinh Tu Bui, Mau Danh Tran, Huu Duc Nguyen and Hai Binh Nguyen
Abstract
The planar Hall effect (PHE) sensor based on a simple giant magneto resistance (GMR) trilayer structure NiFe/Cu/NiFe has been designed and fabricated successfully using conventional clean room fabrication methods. The PHE sensor is integrated by 24 sensor patterns with dimensions of 50 × 50 μm. Influence of individual layer thickness to sensitivity of sensor has been investigated. Sensitivity and planar Hall voltage increases with the decrease of Cu-layer thickness. The results are discussed in terms of the reinforcement of the antiferromagnetic interaction between NiFe layers and shunting current through the layer Cu. The optimum configuration has been found in the structure with the Cu-layer of 1 nm. In this case a single planar Hall effect sensor exhibits a high sensitivity of about 8 μV Oe−1 and a maximal of the signal change as large as ▵V ~ 55 μV. These values are comparable to those of the typical PHE sensor based on complex GMR spin-valve structure. With a high sensitivity and simple structure, this sensor is very promising for practical detection of magnetic beads and identifying multiple biological agents in the environment
