Effect of Torsion Stress on the Offset and Sensitivity of Diagonal and Off-Diagonal GMI in Amorphous Wires.

In this paper, the torsional stress effect on Giant Magneto-Impedance (GMI) was studied in Co-rich amorphous wires. The study, which was conducted in the context of the development of a current clamp based on GMI, considered torsion as a parameter of the influence of this sensor. Both diagonal, Z, and off-diagonal, Z, components of the impedance tensor were investigated.

The Impact of Bending Stress on the Performance of Giant Magneto-Impedance (GMI) Magnetic Sensors.

The flexibility of amorphous Giant Magneto-Impedance (GMI) micro wires makes them easy to use in several magnetic field sensing applications, such as electrical current sensing, where they need to be deformed in order to be aligned with the measured field. The present paper deals with the bending impact, as a parameter of influence of the sensor, on the GMI effect in 100 µm Co-rich amorphous wires. Changes in the values of key parameters associated with the GMI effect have been investigated under bending stress.

High frequency amplitude detector for GMI magnetic sensors.

A new concept of a high-frequency amplitude detector and demodulator for Giant-Magneto-Impedance (GMI) sensors is presented. This concept combines a half wave rectifier, with outstanding capabilities and high speed, and a feedback approach that ensures the amplitude detection with easily adjustable gain. The developed detector is capable of measuring high-frequency and very low amplitude signals without the use of diode-based active rectifiers or analog multipliers.

Software Defined Radio (SDR) and Direct Digital Synthesizer (DDS) for NMR/MRI instruments at low-field.

A proof-of-concept of the use of a fully digital radiofrequency (RF) electronics for the design of dedicated Nuclear Magnetic Resonance (NMR) systems at low-field (0.1 T) is presented. This digital electronics is based on the use of three key elements: a Direct Digital Synthesizer (DDS) for pulse generation, a Software Defined Radio (SDR) for a digital receiving of NMR signals and a Digital Signal Processor (DSP) for system control and for the generation of the gradient signals (pulse programmer).

A three-coil RF probe-head at 2.35 T: Potential applications to the (23)Na and to the hyperpolarized (129)Xe MRI in small animals.

We present in this paper a dedicated home-built RF probe-head for the MRI of rat brain at 2.35 T. This probe consists of an association of three coils: a double-tuned birdcage coil, which could be used for both transmitting and receiving, and a single-tuned surface coil that is used for the only receiving.

ICASENSE: Sensitivity mapping using Independent Component Analysis for parallel Magnetic Resonance Imaging.

Parallel Magnetic Resonance Imaging (MRI) methods employ receiver coils sensitivities to reduce imaging time: reconstruction algorithms need RF field maps which must be measured or estimated. Assuming statistical independence of different regions in a MR image, we consider the sensitivity estimation as a Blind Source Separation (BSS) problem that can be solved with Independent Component Analysis (ICA). This new formulation permits sensitivity maps extraction from only one MR acquisition, without calibration step or acquisition of additional k-space lines.