Challenges and trends in the development of a magnetoresistive biochip portable platform

Sensing magnetic nanoparticles using nano-confined ferromagnetic resonances in a magnonic crystal

“…Previously used sensors include SQuIDs 6 , Hall sensors 7 , ferromagnetic rings 8,9 and magneto-impedance devices 10 . However one of the most widely used methods is that employing magnetoresistive (MR) magnetic field sensors [1][2][3][4][5][11][12][13][14] which are typically fabricated with at least one lateral dimension on the order of 10-100 µm. An MNP is detected when its stray (or 'fringing') magnetic field modifies the quasi-static magnetic configuration in the ferromagnetic MR device.…”

Optimization and Integration of Magnetoresistive Sensors

“…By defining gold pads exactly over the sensors a gold-specific surface chemistry can be used to selectively immobilize the biological probes. 44 Moreover, the limit of detection of the biochip depends not only on the sensor area and the immobilized probes (i.e., probe location, density, orientation) but also on the capacity of target recognition. Therefore, since the biomolecules are labeled with a magnetic particle, they can be attracted and focused into the sensing area using specific structures on the chip promoting probe-target interaction and potentiating the biomolecular recognition.…”

GMR sensors: Magnetoresistive behaviour optimization for biological detection by means of superparamagnetic nanoparticles

“…Moreover, the magnetic moment per particle must be as high as possible to facilitate the detection by means of the magnetoresistive sensor. Finally, in order to have a proper reproducibility in the measurements, the microbeads have to be uniform in shape and magnetic material content, they should have a narrow size distribution and they must be biocompatible (Martins et al, 2010). All these requirements implicate that a compromise has to be found between binding capability, detection simplicity, shape and size features and biocompatibility.…”