title: On-chip magnetometer for characterization of superparamagnetic nanoparticles.
abstract: An on-chip magnetometer was fabricated by integrating a planar Hall magnetoresistive (PHR) sensor with microfluidic channels. The measured in-plane field sensitivities of an integrated PHR sensor with NiFe/Cu/IrMn trilayer structure were extremely high at 8.5 μV Oe(-1). The PHR signals were monitored during the oscillation of 35 pL droplets of magnetic nanoparticles, and reversed profiles for the positive and negative z-fields were measured, where magnitudes increased with the applied z-field strength. The measured PHR signals for 35 pL droplets of magnetic nanoparticles versus applied z-fields showed excellent agreement with magnetization curves measured by a vibrating sample magnetometer (VSM) of 3 μL volume, where a PHR voltage of 1 μV change is equivalent to 0.309 emu cc(-1) of the volume magnetization with a magnetic moment resolution of ~10(-10) emu.
authors.affiliation: Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 711-873, Republic of Korea. cgkim@digst.ac.kr.
authors.forename: Kun Woo
authors.initials: KW
authors.lastname: Kim
authors.forename: Venu
authors.initials: V
authors.lastname: Reddy
authors.forename: Sri Ramulu
authors.initials: SR
authors.lastname: Torati
authors.forename: Xing Hao
authors.initials: XH
authors.lastname: Hu
authors.forename: Adarsh
authors.initials: A
authors.lastname: Sandhu
authors.forename: Cheol Gi
authors.initials: CG
authors.lastname: Kim
mesh_terms: D056656:Lab-On-A-Chip Devices; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D060306:Magnetometry / Q000295:instrumentation; D010316:Particle Size
chemical_list: D058185:Magnetite Nanoparticles