scholarly journals Photothermally and magnetically controlled reconfiguration of polymer composites for soft robotics

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw2897 ◽  
Author(s):  
Jessica A.-C. Liu ◽  
Jonathan H. Gillen ◽  
Sumeet R. Mishra ◽  
Benjamin A. Evans ◽  
Joseph B. Tracy
Keyword(s):  
Magnetic Field ◽  
Shape Memory Polymer ◽  
Composite Films ◽  
Soft Robotics ◽  
Magnetic Actuation ◽  
New Materials ◽  
Photothermal Heating ◽  
Multiple Cycles ◽  
Permanent Shape ◽  
The Magnetic Field

New materials are advancing the field of soft robotics. Composite films of magnetic iron microparticles dispersed in a shape memory polymer matrix are demonstrated for reconfigurable, remotely actuated soft robots. The composite films simultaneously respond to magnetic fields and light. Temporary shapes obtained through combined magnetic actuation and photothermal heating can be locked by switching off the light and magnetic field. Subsequent illumination in the absence of the magnetic field drives recovery of the permanent shape. In cantilevers and flowers, multiple cycles of locking and unlocking are demonstrated. Scrolls show that the permanent shape of the film can be programmed, and they can be frozen in intermediate configurations. Bistable snappers can be magnetically and optically actuated, as well as biased, by controlling the permanent shape. Grabbers can pick up and release objects repeatedly. Simulations of combined photothermal heating and magnetic actuation are useful for guiding the design of new devices.

Dynamic Testing of Magnetic Elastomer Material Prototypes

2019 ◽  
Vol 945 ◽  
pp. 369-373 ◽  
Author(s):  
A.J. Minaev ◽  
J.V. Korovkin
Keyword(s):  
Magnetic Field ◽  
Frequency Response ◽  
Dynamic Characteristics ◽  
Dynamic Testing ◽  
Considerable Effect ◽  
Experimental Results ◽  
New Materials ◽  
Resonant Frequencies ◽  
Input And Output ◽  
The Magnetic Field

This research is aimed at obtaining the experimental dynamic characteristics of new materials (magnetoactive elastomers exposed to the magnetic field). It demonstrates that the strength of a magnetic field has a considerable effect on the increase in the resonant frequencies of tested materials. For tests, we used a vibration stand equipped with virtual meters to visualize the experimental results on a computer display. We herein present an example of recording the frequency response on the magnetic elastomer sample input and output when exposed to vibrations caused by the unbalanced motor forces.

Magnetic Field Activation of Thermoresponsive Shape-Memory Polymer with Embedded Micron Sized Ni Powder

2010 ◽  
Vol 123-125 ◽  
pp. 995-998 ◽  
Author(s):  
Da Wei Zhang ◽  
Yan Ju Liu ◽  
Jin Song Leng
Keyword(s):  
Magnetic Field ◽  
Shape Memory ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Nickel Powder ◽  
Shape Memory Polymer ◽  
Initial Shape ◽  
Silane Coupling ◽  
Shape Memory Composite ◽  
The Magnetic Field

The shape memory polymer (SMP) materials are able to change these shape in response to external stimulus such as stress, temperature, solvent, PH, magnetic, electricity or light. The above-mentioned methods are only to recover initial shape of the deformed SMP, could not give the SMP predeformation. In this paper, magnetic field gives the shape memory polymer composite (SMPC) pre-deformation was studied, through on and off of magnetic field the two-way activation of SMPC was achieved. Shape memory effect of shape memory composite in magnetic field was studied. The SMPC was filled by nickel powder, and the nickel powder was treated by silane coupling agent. The Tg of shape memory composite was measured by dynamic mechanical analyzer. The surface element of treated nickel powder was analysized with XPS. The results indicated that the shape of composite filled by untreated nickel powder did not change in the magnetic field, while the composite filled by treated nickel powder was drawn in the magnetic field. The tensile stretch was decrease with the increase of nickel powder content in the shape memory composite. The addition of silane coupling agent onto nickel powder surface was helpful for the dispersion of nickel in polymer.

Magnetic Shape Memory - Polymer Hybrids

2016 ◽  
Vol 879 ◽  
pp. 133-138 ◽  
Author(s):  
Ilkka Aaltio ◽  
Frans Nilsén ◽  
Joonas Lehtonen ◽  
Yan Ling Ge ◽  
Steven Spoljaric ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Shape Memory ◽  
Single Crystals ◽  
Magnetic Particles ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Raw Material ◽  
Magnetic Shape Memory ◽  
Polymer Hybrids ◽  
The Magnetic Field

Martensitic Ni-Mn-Ga based alloys are known for the Magnetic Shape Memory (MSM) effect, which upon application of an external magnetic field can generate a strain up to 12 % depending on the microstructure of the martensite. The MSM effect occurs by rearrangement of the martensite variants, which is most advantageous in single crystals. Single crystals are, however, rather tedious to produce and there has been attempts to achieve MSM effect in polycrystals. However, in polycrystals the magnetic field induced shape change remains low as compared to single crystals. As an alternative to the former, hybrid MSM materials offer several advantages. When compared to single crystals, hybrids have extended freedom of shaping, lower raw material price, relatively large MSM strain and easier manufacturability. Embedding MSM particles into a suitable polymer matrix results in actuation function or good vibration damping performance. In the present study we report on the mechanical, structural and magnetic properties of MSM polymer hybrids, which are prepared by mixing gas-atomized Ni-Mn-Ga MSM powder into epoxy matrix and aligning the magnetic particles in a magnetic field.

scholarly journals The magnetic field and its effects on the solar atmosphere in high resolution

2006 ◽  
Vol 2 (14) ◽  
pp. 30-40
Author(s):  
Alan M. Title
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Solar Interior ◽  
The Sun ◽  
Magnetic Field Effects ◽  
Entire Surface ◽  
Subsurface Flows ◽  
Outer Atmosphere ◽  
Multiple Cycles ◽  
The Magnetic Field

AbstractThe Sun's magnetic field is produced throughout the solar interior; it emerges and is dispersed by surface and subsurface flows, and then expands above the surface to dominate the structure of the corona. To resolve the effects of the magnetic field it is necessary to image the interior and measure its rotation and flow systems; track the responses of the magnetic fields to flows in the surface; and to follow the evolution of structures in the corona. Because the Sun is dynamic both high spatial and temporal resolution are essential. Because the Sun's magnetic field effects encompass the entire spherical exterior, the entire surface and outer atmosphere must be mapped. And because the magnetic field is cyclic high-resolution observations must be maintained over multiple cycles.

scholarly journals Active photonic platforms for the mid-infrared to the THz regime using spintronic structures

Nanophotonics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2709-2729
Author(s):  
Gaspar Armelles ◽  
Alfonso Cebollada
Keyword(s):  
Magnetic Field ◽  
Electrical Resistivity ◽  
Optical Constants ◽  
Optical Response ◽  
Magnetic Actuation ◽  
Mid Infrared ◽  
Conduction Electrons ◽  
Technological Impact ◽  
The Magnetic Field

AbstractSpintronics and Photonics constitute separately two disciplines of huge scientific and technological impact. Exploring their conceptual and practical overlap offers vast possibilities of research and a clear scope for the corresponding communities to merge and consider innovative ideas taking advantage of each other’s potentials. As an example, here we review the magnetic field modification of the optical response of photonic systems fabricated out of spintronic materials, or in which spintronic components are incorporated. This magnetic actuation is due to the Magneto Refractive Effect (MRE), which accounts for the change in the optical constants of a spintronic system due to the magnetic field induced modification of the electrical resistivity. Due to the direct implication of conduction electrons in this phenomenon, this change in the optical constants covers from the mid-infrared to the THz regime. After introducing the non-expert reader into the spintronic concepts relevant to this work, we then present the MRE exhibited by a variety of spintronic systems, and finally show the different applications of this property in the generation of active spintronic-photonic platforms.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

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