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Institution

DARPA

GovernmentArlington, Virginia, United States
About: DARPA is a government organization based out in Arlington, Virginia, United States. It is known for research contribution in the topics: Laser & The Internet. The organization has 649 authors who have published 1076 publications receiving 58924 citations. The organization is also known as: Defense Advanced Research Projects Agency & Advanced Research Projects Agency.


Papers
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Journal ArticleDOI
Changgu Lee1, Xiaoding Wei1, Jeffrey W. Kysar1, James Hone2, James Hone1 
18 Jul 2008-Science
TL;DR: Graphene is established as the strongest material ever measured, and atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.
Abstract: We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m(-1)) and -690 Nm(-1), respectively. The breaking strength is 42 N m(-1) and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young's modulus of E = 1.0 terapascals, third-order elastic stiffness of D = -2.0 terapascals, and intrinsic strength of sigma(int) = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.

18,008 citations

Journal ArticleDOI
16 Nov 2001-Science
TL;DR: This review describes a new paradigm of electronics based on the spin degree of freedom of the electron, which has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices.
Abstract: This review describes a new paradigm of electronics based on the spin degree of freedom of the electron. Either adding the spin degree of freedom to conventional charge-based electronic devices or using the spin alone has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices. To successfully incorporate spins into existing semiconductor technology, one has to resolve technical issues such as efficient injection, transport, control and manipulation, and detection of spin polarization as well as spin-polarized currents. Recent advances in new materials engineering hold the promise of realizing spintronic devices in the near future. We review the current state of the spin-based devices, efforts in new materials fabrication, issues in spin transport, and optical spin manipulation.

9,917 citations

Journal ArticleDOI
TL;DR: A material strategy for a type of bio-interfaced system that relies on ultrathin electronics supported by bioresorbable substrates of silk fibroin that provides new capabilities for implantable and surgical devices is described.
Abstract: Electronics that are capable of intimate, non-invasive integration with the soft, curvilinear surfaces of biological tissues offer important opportunities for diagnosing and treating disease and for improving brain/machine interfaces. This article describes a material strategy for a type of bio-interfaced system that relies on ultrathin electronics supported by bioresorbable substrates of silk fibroin. Mounting such devices on tissue and then allowing the silk to dissolve and resorb initiates a spontaneous, conformal wrapping process driven by capillary forces at the biotic/abiotic interface. Specialized mesh designs and ultrathin forms for the electronics ensure minimal stresses on the tissue and highly conformal coverage, even for complex curvilinear surfaces, as confirmed by experimental and theoretical studies. In vivo, neural mapping experiments on feline animal models illustrate one mode of use for this class of technology. These concepts provide new capabilities for implantable and surgical devices. Electronics that are capable of intimate integration with the surfaces of biological tissues create opportunities for improving animal/machine interfaces. A bio-interfaced system of ultrathin electronics supported by bioresorbable silk-fibroin substrates is now presented. Mounting such devices on tissue and then allowing the silk to dissolve initiates a conformal wrapping process that is driven by capillary forces.

1,522 citations

Journal ArticleDOI
06 Sep 2011-ACS Nano
TL;DR: Improved wet transfer onto perforated substrates with 2.7 μm diameter holes yields 98% coverage of holes covered with continuous films, allowing the ready use of Raman spectroscopy and transmission electron microscopy to study the intrinsic properties of CVD-grown monolayer graphene.
Abstract: Reproducible dry and wet transfer techniques were developed to improve the transfer of large-area monolayer graphene grown on copper foils by chemical vapor deposition (CVD). The techniques reported here allow transfer onto three different classes of substrates: substrates covered with shallow depressions, perforated substrates, and flat substrates. A novel dry transfer technique was used to make graphene-sealed microchambers without trapping liquid inside. The dry transfer technique utilizes a polydimethylsiloxane frame that attaches to the poly(methyl methacrylate) spun over the graphene film, and the monolayer graphene was transferred onto shallow depressions with 300 nm depth. The improved wet transfer onto perforated substrates with 2.7 μm diameter holes yields 98% coverage of holes covered with continuous films, allowing the ready use of Raman spectroscopy and transmission electron microscopy to study the intrinsic properties of CVD-grown monolayer graphene. Additionally, monolayer graphene transfer...

1,391 citations

Journal ArticleDOI
TL;DR: This article sets out to summarize and clarify the current understanding in this field; explain the underpinnings of breakthroughs reported in the past decade; and provide a critical review of various concepts and experimental results related to nanostructured thermoelectrics.
Abstract: The field of thermoelectrics has progressed enormously and is now growing steadily because of recently demonstrated advances and strong global demand for cost-effective, pollution-free forms of energy conversion. Rapid growth and exciting innovative breakthroughs in the field over the last 10-15 years have occurred in large part due to a new fundamental focus on nanostructured materials. As a result of the greatly increased research activity in this field, a substantial amount of new data--especially related to materials--have been generated. Although this has led to stronger insight and understanding of thermoelectric principles, it has also resulted in misconceptions and misunderstanding about some fundamental issues. This article sets out to summarize and clarify the current understanding in this field; explain the underpinnings of breakthroughs reported in the past decade; and provide a critical review of various concepts and experimental results related to nanostructured thermoelectrics. We believe recent achievements in the field augur great possibilities for thermoelectric power generation and cooling, and discuss future paths forward that build on these exciting nanostructuring concepts.

1,268 citations


Authors

Showing all 650 results

NameH-indexPapersCitations
Zhong Lin Wang2452529259003
Rodney S. Ruoff164666194902
J. Conway1401692105213
James Hone127637108193
Sanjeev Kumar113132554386
Amnon Yariv103108255256
Arun Majumdar10245952464
Steven M. George10050837944
Lixia Zhang9335147817
Yong Ding8223326405
David C. Larbalestier7447920400
Barry Boehm7351543691
Thomas W. Kenny7049423984
Rodney A. Brooks6716743756
Yulin Deng6464116148
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20221
202113
202016
201919
201827
201726