Tag Archives: University of Illinois College of Engineering

Twinkle, Twinkle Little Star (song) could lead to better data storage

A March 16, 2015 news item on Nanowerk features research from the University of Illinois and the song ‘Twinkle, Twinkle Little Star’,

Researchers from the University of Illinois at Urbana-Champaign have demonstrated the first-ever recording of optically encoded audio onto a non-magnetic plasmonic nanostructure, opening the door to multiple uses in informational processing and archival storage.

“The chip’s dimensions are roughly equivalent to the thickness of human hair,” explained Kimani Toussaint, an associate professor of mechanical science and engineering, who led the research.

Specifically, the photographic film property exhibited by an array of novel gold, pillar-supported bowtie nanoantennas (pBNAs)–previously discovered by Toussaint’s group–was exploited to store sound and audio files. Compared with the conventional magnetic film for analog data storage, the storage capacity of pBNAs is around 5,600 times larger, indicating a vast array of potential storage uses.

The researchers have provide a visual image illustrating their work,

Nano piano concept: Arrays of gold, pillar-supported bowtie nanoantennas (bottom left) can be used to record distinct musical notes, as shown in the experimentally obtained dark-field microscopy images (bottom right). These particular notes were used to compose 'Twinkle, Twinkle, Little Star.'  Courtesy of University of Illinois at Urbana-Champaign

Nano piano concept: Arrays of gold, pillar-supported bowtie nanoantennas (bottom left) can be used to record distinct musical notes, as shown in the experimentally obtained dark-field microscopy images (bottom right). These particular notes were used to compose ‘Twinkle, Twinkle, Little Star.’ Courtesy of University of Illinois at Urbana-Champaign

A March 16, 2015 University of Illinois at Urbana-Champaign news release (also on EurekAlert), which originated the news item, describes the research in more detail (Note: Links have been removed),

To demonstrate its abilities to store sound and audio files, the researchers created a musical keyboard or “nano piano,” using the available notes to play the short song, “Twinkle, Twinkle, Little Star.”

“Data storage is one interesting area to think about,” Toussaint said. “For example, one can consider applying this type of nanotechnology to enhancing the niche, but still important, analog technology used in the area of archival storage such as using microfiche. In addition, our work holds potential for on-chip, plasmonic-based information processing.”

The researchers demonstrated that the pBNAs could be used to store sound information either as a temporally varying intensity waveform or a frequency varying intensity waveform. Eight basic musical notes, including middle C, D, and E, were stored on a pBNA chip and then retrieved and played back in a desired order to make a tune.

“A characteristic property of plasmonics is the spectrum,” said Hao Chen, a former postdoctoral researcher in Toussaint’s PROBE laboratory and the first author of the paper, “Plasmon-Assisted Audio Recording,” appearing in the Nature Publishing Group’s Scientific Reports. “Originating from a plasmon-induced thermal effect, well-controlled nanoscale morphological changes allow as much as a 100-nm spectral shift from the nanoantennas. By employing this spectral degree-of-freedom as an amplitude coordinate, the storage capacity can be improved. Moreover, although our audio recording focused on analog data storage, in principle it is still possible to transform to digital data storage by having each bowtie serve as a unit bit 1 or 0. By modifying the size of the bowtie, it’s feasible to further improve the storage capacity.”

The team previously demonstrated that pBNAs experience reduced thermal conduction in comparison to standard bowtie nanoantennas and can easily get hot when irradiated by low-powered laser light. Each bowtie antenna is approximately 250 nm across in dimensions, with each supported on 500-nm tall silicon dioxide posts. A consequence of this is that optical illumination results in subtle melting of the gold, and thus a change in the overall optical response. This shows up as a difference in contrast under white-light illumination.

“Our approach is analogous to the method of ‘optical sound,’ which was developed circa 1920s as part of the effort to make ‘talking’ motion pictures,” the team said in its paper. “Although there were variations of this process, they all shared the same basic principle. An audio pickup, e.g., a microphone, electrically modulates a lamp source. Variations in the intensity of the light source is encoded on semi-transparent photographic film (e.g., as variation in area) as the film is spatially translated. Decoding this information is achieved by illuminating the film with the same light source and picking up the changes in the light transmission on an optical detector, which in turn may be connected to speakers. In the work that we present here, the pBNAs serve the role of the photographic film which we can encode with audio information via direct laser writing in an optical microscope.”

In their approach, the researchers record audio signals by using a microscope to scan a sound-modulated laser beam directly on their nanostructures. Retrieval and subsequent playback is achieved by using the same microscope to image the recorded waveform onto a digital camera, whereby simple signal processing can be performed.

Here’s a link to and a citation for the paper,

Plasmon-Assisted Audio Recording by Hao Chen, Abdul M. Bhuiya, Qing Ding, & Kimani C. Toussaint, Jr. Scientific Reports 5, Article number: 9125 doi:10.1038/srep09125 Published 16 March 2015

This is an open access paper and here is a sample recording courtesy of the researchers and the University of Illinois at Urbana-Champaign,

Crumpling graphene to create a 3D structure and reflattening it afterwards

The reseaarchers at the University of Illinois College of Engineering are quite excited about a new technique for crumpling graphene as a Feb. 17, 2015 news item on ScienceDaily reports,

Researchers at the University of Illinois at Urbana-Champaign have developed a unique single-step process to achieve three-dimensional (3D) texturing of graphene and graphite. Using a commercially available thermally activated shape-memory polymer substrate, this 3D texturing, or “crumpling,” allows for increased surface area and opens the doors to expanded capabilities for electronics and biomaterials.

“Fundamentally, intrinsic strains on crumpled graphene could allow modulation of electrical and optical properties of graphene,” explained SungWoo Nam, an assistant professor of mechanical science and engineering at Illinois. “We believe that the crumpled graphene surfaces can be used as higher surface area electrodes for battery and supercapacitor applications. As a coating layer, 3D textured/crumpled nano-topographies could allow omniphobic/anti-bacterial surfaces for advanced coating applications.”

A Feb. 16, 2015 University of Illinois College of Engineering news release (also on EurekAlert), which originated the news item, describes the nature of graphene and what makes this technique so exciting,

Graphene—a single atomic layer of sp2-bonded carbon atoms—has been a material of intensive research and interest over recent years.  A combination of exceptional mechanical properties, high carrier mobility, thermal conductivity, and chemical inertness, make graphene a prime candidate material for next generation optoelectronic, electromechanical, and biomedical applications.

“In this study, we developed a novel method for controlled crumpling of graphene and graphite via heat-induced contractile deformation of the underlying substrate,” explained Michael Cai Wang, a graduate student and first author of the paper, “Heterogeneous, Three-Dimensional Texturing of Graphene,” which appeared in the journal Nano Letters. ”While graphene intrinsically exhibits tiny ripples in ambient conditions, we created large and tunable crumpled textures in a tailored and scalable fashion.”

“As a simpler, more scalable, and spatially selective method, this texturing of graphene and graphite exploits the thermally induced transformation of shape-memory thermoplastics, which has been previously applied to microfluidic device fabrication, metallic  film patterning, nanowire assembly, and robotic self-assembly applications,” added Nam, whose group has filed a patent for their novel strategy. “The thermoplastic nature of the polymeric substrate also allows for the crumpled graphene morphology to be arbitrarily re-flattened at the same elevated temperature for the crumpling process.”

“Due to the extremely low cost and ease of processing of our approach, we believe that this will be a new way to manufacture nanoscale topographies for graphene and many other 2D and thin-film materials.”

The researchers are also investigating the textured graphene surfaces for 3D sensor applications.

“Enhanced surface area will allow even more sensitive and intimate interactions with biological systems, leading to high sensitivity devices,” Nam said.

The funding agencies for this project were unexpectedly interesting (to me), from the news release,

Funding for this research was provided through the Air Force Office for Scientific Research, American Chemical Society and Brain Research Foundation. [emphasis mine] In addition to Wang, co-authors from Nam’s research group at Illinois include SungGyu Chun, Ryan Han, Ali Ashraf, and Pilgyu Kang.

Here’s a link to and a citation for the paper,

Heterogeneous, Three-Dimensional Texturing of Graphene by Michael Cai Wang, SungGyu Chun, Ryan Steven Han, Ali Ashraf, Pilgyu Kang, and SungWoo Nam. Nano Lett., Article ASAP
DOI: 10.1021/nl504612y Publication Date (Web): February 10, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Dexter Johnson has written a Feb. 20, 2015 post highlighting this work on his Nanoclast blog (on the Institute of Electrical and Electronics Engineers [IEEE] website).

Self-organizing nanotubes and nonequilibrium systems provide insights into evolution and artificial life

If you’re interested in the second law of thermodynamics, this Feb. 10, 2015 news item on ScienceDaily provides some insight into the second law, self-organized systems, and evolution,

The second law of thermodynamics tells us that all systems evolve toward a state of maximum entropy, wherein all energy is dissipated as heat, and no available energy remains to do work. Since the mid-20th century, research has pointed to an extension of the second law for nonequilibrium systems: the Maximum Entropy Production Principle (MEPP) states that a system away from equilibrium evolves in such a way as to maximize entropy production, given present constraints.

Now, physicists Alexey Bezryadin, Alfred Hubler, and Andrey Belkin from the University of Illinois at Urbana-Champaign, have demonstrated the emergence of self-organized structures that drive the evolution of a non-equilibrium system to a state of maximum entropy production. The authors suggest MEPP underlies the evolution of the artificial system’s self-organization, in the same way that it underlies the evolution of ordered systems (biological life) on Earth. …

A Feb. 10, 2015 University of Illinois College of Engineering news release (also on EurekAlert), which originated the news item, provides more detail about the theory and the research,

MEPP may have profound implications for our understanding of the evolution of biological life on Earth and of the underlying rules that govern the behavior and evolution of all nonequilibrium systems. Life emerged on Earth from the strongly nonequilibrium energy distribution created by the Sun’s hot photons striking a cooler planet. Plants evolved to capture high energy photons and produce heat, generating entropy. Then animals evolved to eat plants increasing the dissipation of heat energy and maximizing entropy production.

In their experiment, the researchers suspended a large number of carbon nanotubes in a non-conducting non-polar fluid and drove the system out of equilibrium by applying a strong electric field. Once electrically charged, the system evolved toward maximum entropy through two distinct intermediate states, with the spontaneous emergence of self-assembled conducting nanotube chains.

In the first state, the “avalanche” regime, the conductive chains aligned themselves according to the polarity of the applied voltage, allowing the system to carry current and thus to dissipate heat and produce entropy. The chains appeared to sprout appendages as nanotubes aligned themselves so as to adjoin adjacent parallel chains, effectively increasing entropy production. But frequently, this self-organization was destroyed through avalanches triggered by the heating and charging that emanates from the emerging electric current streams. (…)

“The avalanches were apparent in the changes of the electric current over time,” said Bezryadin.

“Toward the final stages of this regime, the appendages were not destroyed during the avalanches, but rather retracted until the avalanche ended, then reformed their connection. So it was obvious that the avalanches correspond to the ‘feeding cycle’ of the ‘nanotube inset’,” comments Bezryadin.

In the second relatively stable stage of evolution, the entropy production rate reached maximum or near maximum. This state is quasi-stable in that there were no destructive avalanches.

The study points to a possible classification scheme for evolutionary stages and a criterium for the point at which evolution of the system is irreversible—wherein entropy production in the self-organizing subsystem reaches its maximum possible value. Further experimentation on a larger scale is necessary to affirm these underlying principals, but if they hold true, they will prove a great advantage in predicting behavioral and evolutionary trends in nonequilibrium systems.

The authors draw an analogy between the evolution of intelligent life forms on Earth and the emergence of the wiggling bugs in their experiment. The researchers note that further quantitative studies are needed to round out this comparison. In particular, they would need to demonstrate that their “wiggling bugs” can multiply, which would require the experiment be reproduced on a significantly larger scale.

Such a study, if successful, would have implications for the eventual development of technologies that feature self-organized artificial intelligence, an idea explored elsewhere by co-author Alfred Hubler, funded by the Defense Advanced Research Projects Agency [DARPA]. [emphasis mine]

“The general trend of the evolution of biological systems seems to be this: more advanced life forms tend to dissipate more energy by broadening their access to various forms of stored energy,” Bezryadin proposes. “Thus a common underlying principle can be suggested between our self-organized clouds of nanotubes, which generate more and more heat by reducing their electrical resistance and thus allow more current to flow, and the biological systems which look for new means to find food, either through biological adaptation or by inventing more technologies.

“Extended sources of food allow biological forms to further grow, multiply, consume more food and thus produce more heat and generate entropy. It seems reasonable to say that real life organisms are still far from the absolute maximum of the entropy production rate. In both cases, there are ‘avalanches’ or ‘extinction events’, which set back this evolution. Only if all free energy given by the Sun is consumed, by building a Dyson sphere for example, and converted into heat then a definitely stable phase of the evolution can be expected.”

“Intelligence, as far as we know, is inseparable from life,” he adds. “Thus, to achieve artificial life or artificial intelligence, our recommendation would be to study systems which are far from equilibrium, with many degrees of freedom—many building blocks—so that they can self-organize and participate in some evolution. The entropy production criterium appears to be the guiding principle of the evolution efficiency.”

I am fascinated

  • (a) because this piece took an unexpected turn onto the topic of artificial life/artificial intelligence,
  • (b) because of my longstanding interest in artificial life/artificial intelligence,
  • (c) because of the military connection, and
  • (d) because this is the first time I’ve come across something that provides a bridge from fundamental particles to nanoparticles.

Here’s a link to and a citation for the paper,

Self-Assembled Wiggling Nano-Structures and the Principle of Maximum Entropy Production by A. Belkin, A. Hubler, & A. Bezryadin. Scientific Reports 5, Article number: 8323 doi:10.1038/srep08323 Published 09 February 2015

Adding to my delight, this paper is open access.