A new microtensile tester for the study of MEMS materials with the aid of atomic force microscopy

Chasiotis, Ioannis; Knauss, W. G.

doi:10.1177/0018512002042001789

Cited by 78 publications

(89 citation statements)

References 5 publications

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“…At the onset of plastic deformation, the wire undergoes a resistance-dependent geometric change, leading to a small but measurable differential resistance. Traditional approaches to characterizing plasticity 27,28 based on measurements of stress-strain response with a tensometer are not suitable because the mechanics of the elastomeric substrates in these systems dominate the response, by design.…”

Section: Resultsmentioning

confidence: 99%

Fractal design concepts for stretchable electronics

et al. 2014

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Stretchable electronics provide a foundation for applications that exceed the scope of conventional wafer and circuit board technologies due to their unique capacity to integrate with soft materials and curvilinear surfaces. The range of possibilities is predicated on the development of device architectures that simultaneously offer advanced electronic function and compliant mechanics. Here we report that thin films of hard electronic materials patterned in deterministic fractal motifs and bonded to elastomers enable unusual mechanics with important implications in stretchable device design. In particular, we demonstrate the utility of Peano, Greek cross, Vicsek and other fractal constructs to yield space-filling structures of electronic materials, including monocrystalline silicon, for electrophysiological sensors, precision monitors and actuators, and radio frequency antennas. These devices support conformal mounting on the skin and have unique properties such as invisibility under magnetic resonance imaging. The results suggest that fractal-based layouts represent important strategies for hard-soft materials integration.

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Section: Resultsmentioning

confidence: 99%

Fractal design concepts for stretchable electronics

et al. 2014

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“…Direct experimental observations of the deformation mechanisms mentioned above while the materials behavior is measured quantitatively is difficult at the nanoscale even with the recent novel existing approaches (24)(25)(26)(27)(28). We overcome the difficulty by developing microinstrumentation that combines quantitative tensile testing of thin films with the qualitative capabilities of the transmission electron microscope (TEM) so that one can simultaneously measure the stress-strain states in solids and observe the deformation mechanisms during materials testing.…”

Section: Experimental Methodsmentioning

confidence: 99%

Deformation mechanisms in free-standing nanoscale thin films: A quantitative in situ transmission electron microscope study

Haque

Saif

2004

Proc. Natl. Acad. Sci. U.S.A.

241

115

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We have added force and displacement measurement capabilities in the transmission electron microscope (TEM) for in situ quantitative tensile experimentation on nanoscale specimens. Employing the technique, we measured the stress-strain response of several nanoscale free-standing aluminum and gold films subjected to several loading and unloading cycles. We observed low elastic modulus, nonlinear elasticity, lack of work hardening, and macroscopically brittle nature in these metals when their average grain size is 50 nm or less. Direct in situ TEM observation of the absence of dislocations in these films even at high stresses points to a grain-boundary-based mechanism as a dominant contributing factor in nanoscale metal deformation. When grain size is larger, the same metals regain their macroscopic behavior. Addition of quantitative capability makes the TEM a versatile tool for new fundamental investigations on materials and structures at the nanoscale.N anomechanical behavior of materials has gained considerable attention because of the ever-shrinking dimensions of thin-film materials in microelectronics, data storage, and microelectromechanical sensors͞actuators, and also the advancements in bulk nanostructured materials. Mechanical properties of materials are influenced by their length-scales. For example, yield stress of polycrystalline metals increases with a decrease in grain size [Hall-Petch behavior (1, 2)], and strain-gradientdependent strengthening (3-6) occurs when the specimen size is reduced to the micrometer scale. Dislocations have been attributed to cause both of these behaviors as long as the grain size or the thickness is Ͼ100 nm. At smaller length-scales, straingradient-dependent strengthening disappears (7) and reverse Hall-Petch behavior is observed (8-13). Another less understood size effect observed at nanoscale is the reduction of Young's modulus, which has been attributed to specimen density (13) and grain boundary compliance (14,15). Models that attempt to explain the nanoscale size effect are of two basic types: (i) models describing nanocrystalline materials as twophase composites with grain interiors and boundaries, where the mechanical properties are averaged by simple ''rule of mixtures '' (16, 17); and (ii) models considering dislocation motion (10,18,19), grain boundary sliding (20, 21), and diffusion (12, 22) as competing deformation mechanisms. Although the literature has compelling evidence of these size-effects, the underlying deformation mechanisms are not yet well understood (23). Experimental MethodsDirect experimental observations of the deformation mechanisms mentioned above while the materials behavior is measured quantitatively is difficult at the nanoscale even with the recent novel existing approaches (24-28). We overcome the difficulty by developing microinstrumentation that combines quantitative tensile testing of thin films with the qualitative capabilities of the transmission electron microscope (TEM) so that one can simultaneously measure the stress-strain state...

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“…• Any (other than optical) digital image can be processed in the same way provided distortions, aberrations are not too large and uncontrolled [16,17,18].…”

Section: Introductionmentioning

confidence: 99%

Digital image correlation and fracture: an advanced technique for estimating stress intensity factors of 2D and 3D cracks

Roux¹,

Réthoré²,

Hild³

2009

J. Phys. D: Appl. Phys.

210

132

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Abstract. Digital image correlation is a measurement technique that allows one to retrieve displacement fields "separating" two digital images of the same sample at different stages of loading. Because of its remarkable sensitivity, it is not only possible to detect cracks with sub-pixel opening, which would not be visible, but also to provide accurate estimates of stress intensity factors. For this purpose suitable tools have been devised to minimize the sensitivity to noise. Working with digital images allows the experimentalist to deal with a wide range of scales from atomistic to geophysical one with the same tools. Various examples are shown at different scales, as well as some recent extensions to three dimensional cracks based on X-ray Computed micro-tomographic images.

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A new microtensile tester for the study of MEMS materials with the aid of atomic force microscopy

Cited by 78 publications

References 5 publications

Fractal design concepts for stretchable electronics

Fractal design concepts for stretchable electronics

Deformation mechanisms in free-standing nanoscale thin films: A quantitative in situ transmission electron microscope study

Digital image correlation and fracture: an advanced technique for estimating stress intensity factors of 2D and 3D cracks

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