No abstract

Diffusion in breast lesions follows a non-Gaussian distribution. MK enables differentiation and characterisation of breast lesions, providing new insights into microstructural complexity. To confirm these results, further investigation in a broader sample should be performed.

Magnetic bead sensors based on the planar Hall effect in thin films of exchange-biased permalloy have been fabricated and characterized. Typical sensitivities are 3 μV/Oe mA. The sensor response to an applied magnetic field has been measured without and with coatings of commercially available 2 μm and 250 nm magnetic beads used for bioapplications (Micromer-M and Nanomag-D, Micromod, Germany). Detection of both types of beads and single bead detection of 2 μm beads is demonstrated, i.e., the technique is feasible for magnetic biosensors. Single 2 μm beads yield 300 nV signals at 10 mA and 15 Oe applied field.

Superparamagnetic labels, 400 nm dextran iron oxide particles and 2 μm polymer encapsulated iron oxide microspheres, with biomolecules immobilized on the surface, e.g., the enzyme horseradish peroxidase (20–40 molecules per label) were controllably placed on chip sites (5×15 μm2) using tapered Al current lines (10–20 mA current) and moved to and from adjacent spin valve sensors [2×6 μm,2, magnetoresistance (MR) ∼5%]. Average MR signals of 1.2 and 0.6 mV were obtained for the detection of bulk numbers of 400 nm and 2 μm labels respectively using an on-chip field of 15 Oe and a sense current of 5 mA. The moment per label was calculated at 5×10−13 emu for the 400 nm labels and 5×10−12 emu for the 2 μm labels, illustrating the higher density of the 400 nm particles. MR signals of ∼100 μV were obtained for single 2 μm labels positioned over the spin valve sensor using an on-chip field of 15 Oe and 8 mA sense current. The corresponding sensor saturation occurred at ∼1 mV, with a noise level of ∼10 μV. The estimated maximum MR signal for one 2 μm label directly on top of the sensor was ∼400 μV. Biotechnological applications include high sensitivity biosensors and biochips for protein and DNA screening.