Wheatstone bridge-giant magnetoresistance (GMR) sensors based on Co/Cu multilayers for bio-detection applications

Abstract

Abstract.A Wheatstone bridge-giant magnetoresistance (GMR) sensor was successfully developed for a potential biomaterial detection. In order to achieve this, a giant magnetoresistive [Co(1.5nm/Cu(1.0nm)] 20 multilayer structures have been fabricated by DC magnetron sputtering method, showing a magnetoresistance (MR) of 2.7%. The X-Ray diffraction (XRD) patterns showed that Co/Cu film multilayer has a high degree of crystallinity with a single peak corresponding to face-centered cubic (111) structure at 2 = 44.1 . Co/Cu multilayers exhibit a soft magnetic behavior with the saturation magnetization (Ms) of 1489 emu/cc and the coercivity (Hc) of 11.2 Oe. The magnetite Fe 3 O 4 nanoparticles used as a bimolecular labels (nanotags) were synthesized via co-precipitation method, exhibiting a soft magnetic behavior with Ms of 77.16 emu/g and Hc of 49 Oe. XRD patterns and transmission electron microscopy (TEM) images showed that Fe 3 O 4 was well crystallized and it grew in their inverse spinel structure with an average size of around 10 nm. The GMR sensor design was used to detect a biomolecules of streptavidin magnetic particles with concentration 10, 20, 30, and 40 l/ml and -amylase enzyme with consentration 10, 20, 30, and 40 l/ml captured using polyethylene glycol (PEG)/ Fe 3 O 4 nanoparticles. Various applied magnetic fields of 0-650 Gauss have been performed using electromagnetic with the various currents of 0-5 A. Here, the final value of the output voltage signals for the streptavidin magnetic particles concentration is 1.2 mV (10 l/ml). The output voltage changes with the increase of concentration. It was reported that the output voltage signal of the Wheatstone bridge exhibits log-linear function in real time measurement of the concentration of streptavidin magnetic particles and -amylase enzyme respectively, making the sensor suitable for use as a biomolecule concentration detector. Thus, the combination of Co/Cu multilayer, Wheatstone bridge, magnetite and PEG polymer has potential application to be used in bio-detection applications where ultra-small bio-labels are needed.

A synthesis of polyethylene glycol (PEG)-coated magnetite Fe3O4 nanoparticles and their characteristics for enhancement of biosensor

“…Therefore, for biomedical applications, one important problem to consider in the use of Fe 3 O 4 nanoparticles is stabilization. To increase their stabilization, Fe 3 O 4 nanoparticles have been stabilized by the formation of polymer layers on the surface of magnetic nanoparticles, using dextran, gen, cell, poly (vinyl alcohol) (PVA), enzyme, protein, gelatin, etc [4][5][6][7][8][9].…”

The Synthesis of CuO-Based Nanofluids as a Cooling Media

“…The two-step method is the method most widely used for the preparation of nanofluids. In this method, nanoparticles must be prepared in advance through a physical or chemical synthesis process, such as: co-precipitation [21], sol-gel, spray pyrolysis and others. The most popular and effective two-step method for preparing long-stable, homogeneously dispersed nanofluids is ultrasonication.…”

Recent advances in magnetoresistance biosensors: a short review

“…This discovery won them a Nobel prize in 2007. The ability to convert magnetic signal into an electrical one has caused the successful realization of magnetic field sensors for a large variety of applications including: hard disk drives, current sensing, magnetic random access memory, position sensing, pressure measurement, and magnetic biosensors [2][3][4][5][6][7][8][9][10][11].…”