![](https://fisika.fmipa.ugm.ac.id/wp-content/uploads/sites/440/2023/02/Magnetic-Nanoparticle-Detection-Using-Wheatstone-Bridge-Giant-Magnetoresistance-GMR-Sensor-with-Double-CoFeB-Spin-Valve-Thin-Films-Key-Engineering-Materials-Vol.-884-2021-pp.-348-352-825x250.png)
Edi Suharyadi, Taufikuddin Alfansuri
https://doi.org/10.4028/www.scientific.net/KEM.884.348
Journal: Key Engineering Materials
Vol. 884, May 2021, 348-352
Abstract
The Wheatstone bridge-giant magnetoresistance (GMR) sensor with single and double spin valve thin film was successfully developed for potential biomolecular detection. The GMR sensor with spin valves structure of [Ta (2nm)/IrMn (10nm)/CoFe (3nm)/Cu (2,2nm)/CoFeB (10nm)/Ta (5nm)] was fabricated using DC Magnetic Sputtering method. The Fe3O4 magnetic nanoparticles were synthesized by the co-precipitation method as a magnetic label. The magnetic properties of the Fe3O4 nanoparticles measured are the saturation magnetization (Ms) of 77.7 emu/g, remanence magnetization (Mr) of 7.7 emu/g, and coercivity (Hc) of 49 Oe. The X-ray diffraction pattern showed the inverse cubic spinel structure with an average crystal size of about 20.1 nm. Fe3O4 magnetic nanoparticles with various concentrations were used to be detected using a GMR sensor. The output voltage of the GMR sensor with the single and double spin-valve increased from 1.7 to 3.9 mV and 2.9 to 5.3 mV with the increase of the Fe3O4 concentration from 0 to 20 mg/mL, respectively.