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A disposable card incorporating specific DNA probes targeting the 16 S rRNA gene of Streptococcus suis was developed for magnetically labeled target DNA detection. A singlestranded target DNA was hybridized with the DNA probe on the SPA/APTES/PDMS/Si asprepared card, which was subsequently magnetically labeled with superparamagnetic beads for detection using an anisotropic magnetoresistive (AMR) sensor. An almost linear response between the output signal of the AMR sensor and amount of single-stranded target DNA varied from 4.5 to 18 pmol was identified. From the sensor output signal response towards the mass of magnetic beads which were directly immobilized on the disposable card surface, the limit of detection was estimated about 312 ng ferrites, which corresponds to 3.8 μemu. In comparison with DNA detection by conventional biosensor based on magnetic bead labeling, disposable cards are featured with higher efficiency and performances, ease of use and less running cost with respects to consumables for biosensor in biomedical analysis systems operating with immobilized bioreceptor.

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This paper describes the route, from simulations toward experiments, for optimizing the magnetoelectric (ME) geometries for vortex magnetic field sensors. The research is performed on the base of the Metglas/Piezoelectric (PZT) laminates in both open and closed magnetic circuit (OMC and CMC) geometries with different widths (W), lengths (L), and diameters (D). Among these geometries, the CMC laminates demonstrate advantages not only in their magnetic flux distribution, but also in their sensitivity and in their independence of the position of the vortex center. In addition, the ME voltage signal is found to be enhanced by increasing the magnetostrictive volume fraction. Optimal issues are incorporated to realize a CMC-based ME double sandwich current sensor in the ring shape with D × W = 6 mm × 1.5 mm and four layers of Metglas. At the resonant frequency of 174.4 kHz, this sensor exhibits the record sensitivity of 5.426 V/A as compared to variety of devices such as the CMC ME sensor family, fluxgate, magnetoresistive, and Hall-effect-based devices. It opens a potential to commercialize a new generation of ME-based current and (or) vortex magnetic sensors.

A magnetoelectric 2-D geomagnetic device for the precisely angular position computation is provided. The magnetic sensor module consists of two Metglas/PZT magnetoelectric 1-D sensors in an orthogonal arrangement. The sensor signals are excited and detected by a self-made digital lock-in amplifier. For mapping output sensor signals, normalization was performed on the operational module. Both spatial (azimuth and pitch) angles are then easily computed while rotating and/or swinging the sensor module. This simple and low-cost geomagnetic device is integrated with mobile transceivers for automatic determination and control of the latter antenna direction with respect to the position of the geostationary satellite in communication.Index Terms-Digital signal processing, geomagnetism, magnetic field measurement, magnetoelectric effects.