Fabrication of scrolled magnetic thin film patterns

Min, Seong-Gi; Lim, Jin-Hee; Gaffney, John; Kinttle, Kristofer; Małkiński, L.

doi:10.1063/1.3679555

Cited by 3 publications

(3 citation statements)

References 17 publications

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“…The diameter of curvature is obtained by balancing the bending moment on the surface with the flexural rigidity as shown by Timoshenko in 1925 . The equation for the diameter of the tube can be obtained as

D = \frac{(\frac{E_{1}}{E_{2}}) t_{1}^{4} + 4 t_{1}^{3} t_{2} + 6 t_{1}^{2} t_{2}^{2} + 4 t_{1} t_{2}^{3} + (\frac{E_{2}}{E_{1}}) t_{2}^{4}}{6 Δ ε t_{1} t_{2} (t_{1} + t_{2})}

Where, E and t are the Young's modulus and the thickness of the films and subscripts 1 and 2 denote the SU‐8 and TE film. Δε denotes the relative stress between the two films.…”

Section: Mechanics Of Stress‐induced 2d To 3d Transformationmentioning

confidence: 99%

Strain‐Induced Rolled Thin Films for Lightweight Tubular Thermoelectric Generators

Singh

Kutbee

Ghoneim

et al. 2017

Adv Materials Technologies

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(Te)-based TE alloy materials are known for its room-temperature stability and ease in deposition, high electrical conductivity and low thermal conductivity. Thus, high-quality TE devices can be attained by using antimony telluride (Sb 2 Te 3 ) and bismuth telluride (Bi 2 Te 3 ) in various forms, including single crystal, thin films, and different nanostructures. [1,4] Many techniques have been used to fabricate these in thin-film forms, such as physical vapor deposition, metal organic chemical vapor deposition (MOCVD), and molecular beam epitaxy (MBE). [1] Compared with MOCVD or MBE, sputtering is preferred for deposition of these TE materials, due to its ease of process control with its high throughput and reliability, whose deposition thickness is limited to achieve longer thermopiles. For longer thermopiles, whereas in-plane configuration is easily available by lateral deposition or coating, same plane surface hurts the thermal gradient by in-plane heat conduction and thermal convection between two zones of varied temperatures. Therefore, achieving a vertically aligned out-of-plane thermopiles would eliminate such heat convectioninduced performance compromise. Another demerit of conventional TE devices is they have high density thus they are heavy, which somehow restricts their use in energy harvesting applications. [5] Here, we show a polymer-assisted strain-induced structural transformation of thin films of telluride-based TE materials into an unprecedented 4 cm long seamless 3D lightweight tubular architecture. The strain-induced self-rolled tube is attained through formation of the tensile/stressed layer on the desired thin film (to be rolled) and then is lifted off with the optimized chemistry and mechanism of dissolving sacrificial layer from desired substrate. Both the approaches, bottom-up as well as top-down, are explained for the formation of self-rolling semiconductor microtubes and nanotubes structure. [6][7][8][9][10][11][12][13][14] Bottom-up aspect is for high-quality-strained layers with appropriate composition and thickness, whereas the top-down aspect exposes sidewalls of the desired thin film for lateral etching of the sacrificial layer in order to release the strained thin layer along with the desired TE film from the subsequent substrate. [7][8][9][10][11][12][13][14] Later approach determines the precise tube orientation, dimensions, and the number of rotations as per application prospects of TE applications. As a result, selfrolling tubular micro-and nanostructures can be assembled Thermoelectric generators (TEGs) are interesting energy harvesters of otherwise wasted heat. Here, a polymer-assisted generic process and its mechanics to obtain sputtered thermoelectric (TE) telluride material-based 3D tubular structures with unprecedented length (up to seamless 4 cm and further expandable) are shown. This length allows for large temperature differences between the hot and the cold ends, a critical but untapped enabler for high power generation. Compared with a flat slab, better area effici...

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D = \frac{(\frac{E_{1}}{E_{2}}) t_{1}^{4} + 4 t_{1}^{3} t_{2} + 6 t_{1}^{2} t_{2}^{2} + 4 t_{1} t_{2}^{3} + (\frac{E_{2}}{E_{1}}) t_{2}^{4}}{6 Δ ε t_{1} t_{2} (t_{1} + t_{2})}

Where, E and t are the Young's modulus and the thickness of the films and subscripts 1 and 2 denote the SU‐8 and TE film. Δε denotes the relative stress between the two films.…”

Section: Mechanics Of Stress‐induced 2d To 3d Transformationmentioning

confidence: 99%

Strain‐Induced Rolled Thin Films for Lightweight Tubular Thermoelectric Generators

Singh

Kutbee

Ghoneim

et al. 2017

Adv Materials Technologies

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“…The films fabricated in our group [48,53,54] were isotropic in the film plane. Therefore, the effect of the self-rolling on the static magnetic properties was easier to interpret than for the anisotropic films.…”

Section: Link Between the Shape And Magnetic Propertiesmentioning

confidence: 99%

“…Aluminum sacrificial surface layer was used to grow Au/Ti bilayers and was etched with KOH-based solution [47]. Our group used 50 nm thick Cu film on Si as a sacrificial layer to deposit magnetic films [53,54].…”

Section: A Sacrificial Layermentioning

confidence: 99%

Magnetic Micro-Origami

Małkiński¹,

Eskandari²

2016

Magnetic Materials

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Microscopic origami figures can be created from thin film patterns using surface tension of liquids or residual stresses in thin films. The curvature of the structures, direction of bending, twisting, and folding of the patterns can be controlled by their shape, thickness, and elastic properties and by the strength of the residual stresses. Magnetic materials used for micro-and nano-origami structures play an essential role in many applications. Magnetic force due to applied magnetic field can be used for remote actuation of microrobots. It can also be used in targeted drug delivery to direct cages loaded with drugs or microswimmers to transport drugs to specific organs. Magnetoelastic properties of free-standing micro-origami patterns can serve for stress or magnetic field sensing. Also, the stress-induced anisotropy and magnetic shape anisotropy provide a convenient method of tuning magnetic properties by designing a shape of the microorigami figures instead of varying the composition of the films. Micro-origami figures can also serve as building blocks for two-and three-dimensional meta-materials with unique properties such as negative index of refraction. Micro-origami techniques provide a powerful method of self-assembly of magnetic circuits and integrating them with microelectro-mechanical systems or other functional devices.

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