Papers by Samuel Ríos Sánchez 6IV9
Physical Review Letters, 2011
Together with the well-known ferro-and antiferromagnetic ordering, nature has created a variety o... more Together with the well-known ferro-and antiferromagnetic ordering, nature has created a variety of complex helical magnetic configurations. Here, we design and investigate three-dimensional microhelix coil structures that are radial-, corkscrew-, and hollow-bar-magnetized. The magnetization configurations of the differently magnetized coils are experimentally revealed by probing their specific dynamic response to an external magnetic field. Helix coils offer an opportunity to realize microscale geometries of the magnetic toroidal moment, observed so far only in bulk multiferroic materials.
Micromotors with built-in compasses
Chemical Communications, 2012
We demonstrate here that iron containing rolled-up microtubular engines can be magnetized and act... more We demonstrate here that iron containing rolled-up microtubular engines can be magnetized and act as compass needles - they sense the direction of an external magnetic field from afar and align the directionalities of their movements according to the external field, in a similar fashion to magnetotactic bacteria.
PLoS ONE, 2014
In this study, we demonstrate closed-loop motion control of self-propelled microjets under the in... more In this study, we demonstrate closed-loop motion control of self-propelled microjets under the influence of external magnetic fields. We control the orientation of the microjets using external magnetic torque, whereas the linear motion towards a reference position is accomplished by the thrust and pulling magnetic forces generated by the ejecting oxygen bubbles and field gradients, respectively. The magnetic dipole moment of the microjets is characterized using the U-turn technique, and its average is calculated to be 1.3|10 210 A.m 2 at magnetic field and linear velocity of 2 mT and 100 mm/s, respectively. The characterized magnetic dipole moment is used in the realization of the magnetic force-current map of the microjets. This map in turn is used for the design of a closed-loop control system that does not depend on the exact dynamical model of the microjets and the accurate knowledge of the parameters of the magnetic system. The motion control characteristics in the transient-and steady-states depend on the concentration of the surrounding fluid (hydrogen peroxide solution) and the strength of the applied magnetic field. Our control system allows us to position microjets at an average velocity of 115 mm/s, and within an average region-of-convergence of 365 mm.
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Papers by Samuel Ríos Sánchez 6IV9