Generalized impedance converters (GIC) are electronic circuits which have been widely used as controllable impedance in AC regime, especially in active filter synthesis. In the work presented, the ...GIC is used as a biasing circuit of a magnetoresistive current sensor (Wheatstone bridge) which is located inside the GIC itself. In this case, the GIC works under DC bias unlike its usual AC bias use
The effect of film thickness on the magnetic and electrical properties of permalloy magnetoresistive sensors is investigated. The thicknesses of permalloy thin films used are between 15 and 200 nm. ...The films are deposited on glass substrates by electron beam deposition and then formed into 10 μm × 50 μm patterns by photolithography. The coercivity and the magnetic anisotropy field of the films are increased by patterning. The coercivity of patterned film increases with increasing film thickness in the range of 15 to 45 nm and decreases above 80 nm. This is because the magnetization reversal process in thinner films is caused by rotation magnetization with the buckling magnetic domain structure. While, in thicker films it is caused by the magnetic domain wall displacement. On the other hand, the magnetic anisotropy field of patterned film increases linearly with thickness, due to an increase of the demagnetizing field. The half width of the magnetoresistive response curve and the output voltage of the magnetoresistive sensor decrease with increasing film thickness, because of the increasing demagnetizing field. Moreover, the discontinuity of output voltage due to the Barkhausen effect decreases with increasing film thickness. The Barkhausen noise is related to the occurrence and sudden extinction of buckling magnetic domains in thinner films and to the sudden movement of magnetic domain walls in thicker films.
In this paper, we present a novel type of biaxial accelerometer based on a polydimethylsiloxane (PDMS) structure as the mass–spring system and using magnetoresistive (MR) sensors as the detection ...method. The proof mass of the sensor is a mushroom-shaped polymer magnet made of PDMS filled with permanent magnet powder, whose minute movement under lateral acceleration is precisely sensed by a set of MR sensors. The device aims at consumer electronics applications of low g range and low frequency, such as inclination measurements and motion sensing. An experimental device has been successfully fabricated which showed a linear transfer curve without significant hysteresis. A sensitivity of 0.32mV/(Vg) was obtained.
Magnetic nanoparticles (MNPs) have been studied widely as a powerful diagnostic probe and therapeutic agent for biomedical applications. In recent years, they are also found to be sensitive to ...magnetoresistive (MR) devices and MNP-MR biochips are predicted to be more affordable, portable and sensitive than the conventional optical detection methods. In this MNP-MR biochip design, MNP probes are required to have high magnetic moment, high susceptibility, and be target-specific. This review summarizes recent advances in chemical syntheses and functionalization of MNPs with controlled magnetic properties for sensitive MR detection and for bio-sensing applications.
PDF
