Indonesia Conference Directory

In this paper a potential use of giant magnetoresistance (GMR) sensors in Wheatstone bridge is presented in order to detect polyethylene glycol (PEG)-coated magnetite (Fe3O4) nanoparticles as biomolecular labels (nano-tags) in magneto-biodetection technology. The GMR Co/Cu multilayer structures were fabricated by DC magnetron sputtering method. The magnetoresistance (MR) of Co/Cu was 2.7%. The Fe3O4 were synthesized via co-precipitation method, exhibiting a soft magnetic behavior with saturation magnetization (M_s) of 77.2 emu/gram and coercivity (H_c) of 49 Oe respectively. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images showed that Fe3O4 was well crystallized and confirmed the formation of inverse spinel structure with an average size of around 12 nm. Formation of PEG/Fe3O4 was confirmed by Fourier transform infrared spectroscopy (FTIR). As the PEG concentration is decreased the overall saturation magnetization of the coated nanoparticles initially decreases due to the decrease iron content with a minimum of 37.2 emu/gram for nanoparticles with the smallest Fe3O4 content. Various applied magnetic fields of 0-650 Gauss have been performed using electromagnetic with the various currents of 0-5 A. The final value of the output voltage signals for the Fe3O4 is 1.76 mV. The output voltage changes with the increase of concentration of PEG. The developed sensors are used to monitor real-time binding signals and portable into a Wheatstone bridge for the magneto-biodetection at ultra-low concentration using magnetic nanoparticles coated with PEG as reporters.