DETEKSI NANOPARTIKEL SUPERPARAMAGNETIK Fe3O4 DENGAN SENSOR GIANT MAGNETORESITANCE (GMR) BERBASIS LAPISAN TIPIS Co/Cu MULTILAYER DENGAN METODE FOUR POINT PROBE SYSTEM; DETECTION OF IRON-OXIDE SUPERPARAMAGNETIC NANOPARTICLES USING GIANT MAGNETORESITANCE (GMR) SENSORS BASED ON THIN FILM Co/Cu MULTILAYERS WITH FOUR POINT PROBE SYSTEM METHOD

Pardede, Indra, Edi Suharyadi

2015 | Disertasi | FMIPA

This research was carried out the detection of superparamagnetic nanoparticles iron-oxide (SPIONs) based on Co/Cu thin film multilayers GMR sensors using Standard Four Point Probe Methods (SFPPM). [Co(1,5nm)/Cu(x)]20 thin film multilayers fabricated using DC magnetron sputtering method with variation of the Cu-layer thickness (x = 0.8, 0.9, 1.0, 1.1 and 1.2 nm). The result of measurement MR percentage by applied an external magnetic field ± 600 Gauss parallel to the sample, initially increased monotonically with the increase in the thickness of the Cu layer until it reaches the maximum value at the thickness of about 1nm and further decreased. The MR percentage was about 4.49%, 7.41%, 17.43%, 13.03% and 10.25% respectively. The present of MR phenomenon make sensors GMR potentially for detection of magnetic nanoparticles applications. The SPIONs to be detected were synthesized via coprecipitation method. Characterization using X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM) exhibiting that SPIONs well crystallized and grow in their inverse spinel structures, highly uniform morphology with grain size 12.940 ± 0,3nm and M-H loop characteristics exhibiting soft magnetic behaviour with saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) is 77.164 emu/g, 7.682 emu/g and 0.0486 kOe respectively. Detection of SPIONs were dispersed in ethanol and prepared with different concentration ( 0.1 mg/ml, 1 mg/mL, 10 mg /ml and 100 mg/ml), were conducted using GMR sensor based on thin film [Co (1,5nm/Cu(x)]20 multilayers (x = 0,9 and 1.0 nm) at room temperature. The resistance deviations of thin film after coated nanoparticles showed that the GMR sensors based on Co/Cu multilayer successfully to detect the presence of nanoparticles. The response signal from resistance deviations GMR sensors based on thin film [Co(1,5nm)/Cu (x)]20 multilayers (x = 0.9, and 1.0 nm) exhibits log-linear function of concentration SPIONs. These results indicate that GMR sensors based on Co/Cu multilayer combined with SPIONs has potential to be used in the biosensor applications.

Kata Kunci : Giant magnetoresistance (GMR); magnetic sensors; superparamagnetic iron-oxide nanoparticles (SPIONs)