Magneto-Electronics
 | Elastic magnetic sensor with isotropic sensitivity for in-flow detection of magnetic objects
We present a conceptually new approach for the detection of magnetic objects flowing through a fluidic channel. We produce an elastic and stretchable magnetic sensor and wrap it around a capillary tubing. Thus, the stray fields induced by the flowing magnetic objects can be detected virtually in all directions (isotropic sensitivity), which is unique for the elastic sensor compared to rigid planar counterparts. In combination with magnetic particles as biomarkers, this elastic magnetic sensor can be considered as a new generation of biosensors for cells or even biomolecules evading many difficulties of traditional optical detection methods like low speed, excitation, bulky and expensive equipment, biomolecular amplification and the need for transparent packaging. | |
Magnetic microhelix coil structuresWe 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.E. J. Smith et al., Physical Review Letters 107, 097204 (2011) URL PDF | ||
Rolled-up magnetic sensor for in-flow detection of magnetic objectsRolled-up nanotech is used to fabricate magnetic sensor devices, which are directly integrated into fluidic architectures. Strain engineering is applied to roll-up a thin layer stack revealing giant magnetoresistence (GMR). In this way, the rolled-up tube acts as a fluidic channel, while the integrated GMR sensor responds to a magnetic field. In-flow detection of ferromagnetic CrO2 nanoparticles embedded in a biocompatible polymeric hydrogel shell is highlighted. The advantage of rolled-up devices is their integrability into existing on-chip technologies and the ability to combine several functions into a single architecture, possibly leading to a fully operational lab-in-a-tube system.I. Mönch et al., ACS Nano 5, 7436 (2011) URL PDF | ||
Stretchable magnetoelectronicsWe add a new member to the family of stretchable electronic devices: A flexible and stretchable magnetoelectronic sensor element based on the giant magnetoresistance (GMR) effect. The remarkable performance of the fabricated GMR multilayers upon stretching relies on efficient wrinkling of the GMR films on top of a free-standing rubber membrane. The operation of the device was demonstrated on a proof-of-concept level by attaching it to a curved surface and measuring the sensor's dynamic response to a magnetic field of a rotating magnet. This flexible magnetic sensor opens a straightforward possibility for the integration into existing stretchable electronic systems to realize smart hybrid magnetic and electronic devices with the functionality to sense and to respond to magnetic fields.M. Melzer et al., Nano Letters 11, 2522 (2011) URL PDF | ||
| | First magnetic rolled-up microtubes demonstratedMagnetic rolled-up microtubes are fabricated for the first time, and their hysteresis curves are measured. The tubes consist of semiconductor/magnetic radial superlattices rolled up from a thin solid hybrid material film. The magnetic properties reflect the change of symmetry adopted by the film, once it forms into a cylindrical structure.Ch. Deneke et al., Nanotechnology 20, 045703 (2009) DOI: 10.1088/0957-4484/20/4/045703 (2008) URL PDF Ch. Deneke et al., Physica Status Solidi C 5, 2704 (2008) URL PDF | |
Towards flexible magnetoelectronicsStrongly enhanced GMR on flexible substrates is reported for Co/Cu multilayers deposited on plastics by introducing a photoresist buffer layer. GMR values of Co/Cu multilayers on buffered flexible substrates are even larger than those on thermally oxidized Si substrates due to an increased antiferromagnetic coupling fraction. The GMR effect can be easily tuned mechanically by substrate stretching.Y. F. Chen et al., Advanced Materials 20, 3224 (2008) URL PDF | ||