Ballistic magnetoresistance in nickel single-atom conductors

Large ballistic magnetoresistance (BMR) has been measured in Ni single-atom conductors electrodeposited between microfabricated thin films. These measurements irrefutably eliminate any magnetostriction related artifacts in the BMR effect.Comment: 12 pages, 3 Figure

Altering magnetostrictive strain pathways via morphology of spontaneously aligned domains

In contrast to the use of a mazelike (randomly oriented) magnetic domain morphology or the application of a prestress, it is shown that spontaneously aligned domain morphology is capable of reducing the switching fields and producing a variety of magnetostriction strain pathways that are otherwise not possible by conventional materials approaches (composition and microstructure) alone. Using phase field micromagnetic microelastic modeling, the underlying magnetic domain evolution and the resultant strain behavior of giant magnetostriction materials with uniaxial magnetic anisotropy is explained by analyzing elastostatic interactions across domain walls arising from magnetostriction-induced strain mismatch. © 2011 American Physical Society

IMECE2002-34387 ELECTROCHEMICALLY ACTUATED MICROVALVES FOR MICROFLUIDIC SYSTEMS

ABSTRACT Electrochemical actuation is used to make active control elements for microfluidic applications that require no moving mechanical parts. Electrochemical bubbles were generated directly inside the micro-channels, which serve as valves. Bubble formation and its physical interaction with the fluid were visualized using epi-fluorescent microscopy, which shows that the valve completely stops the flow. Valve closing/opening was quantitatively characterized for flow rates ranging from ≈5 mm/s to 27 mm/s (inlet pressures 102 kPa to 105 kPa). It was found that valves could be closed/opened in relatively short times (≈30 ms) and consume low power (≈10 µJ). The current versus time curves measured at progressively higher voltages (from 3.8 V to 5.2 V) shows a linear relationship between the total charges transferred during electrolysis and the resulting bubble size. The large volume change associated with liquid to gas transformation can also be used to displace liquid for dosing or pumping