Mon, 15 Feb 2010 04:05:31 +0000

Abstract:
Material scientists at the Nano/Bio Interface Center of the University of Pennsylvania have demonstrated the transduction of optical radiation to electrical current in a molecular circuit. The system, an array of nano-sized molecules of gold, respond to electromagnetic waves by creating surface plasmons that induce and project electrical current across molecules, similar to that of photovoltaic solar cells.

University of Pennsylvania Material Scientists Turn Light Into Electrical Current Using a Golden Nanoscale System

Philadelphia, PA | Posted on February 13th, 2010

The results may provide a technological approach for higher efficiency energy harvesting with a nano-sized circuit that can power itself, potentially through sunlight. Recently, surface plasmons have been engineered into a variety of light-activated devices such as biosensors.

It is also possible that the system could be used for computer data storage. While the traditional computer processor represents data in binary form, either on or off, a computer that used such photovoltaic circuits could store data corresponding to wavelengths of light.

Because molecular compounds exhibit a wide range of optical and electrical properties, the strategies for fabrication, testing and analysis elucidated in this study can form the basis of a new set of devices in which plasmon-controlled electrical properties of single molecules could be designed with wide implications to plasmonic circuits and optoelectronic and energy-harvesting devices.

Dawn Bonnell, a professor of materials science and the director of the Nano/Bio Interface Center at Penn, and colleagues fabricated an array of light sensitive, gold nanoparticles, linking them on a glass substrate. Minimizing the space between the nanoparticles to an optimal distance, researchers used optical radiation to excite conductive electrons, called plasmons, to ride the surface of the gold nanoparticles and focus light to the junction where the molecules are connected. The plasmon effect increases the efficiency of current production in the molecule by a factor of 400 to 2000 percent, which can then be transported through the network to the outside world.

In the case where the optical radiation excites a surface plasmon and the nanoparticles are optimally coupled, a large electromagnetic field is established between the particles and captured by gold nanoparticles. The particles then couple to one another, forming a percolative path across opposing electrodes. The size, shape and separation can be tailored to engineer the region of focused light. When the size, shape and separation of the particles are optimized to produce a "resonant" optical antennae, enhancement factors of thousands might result.

Furthermore, the team demonstrated that the magnitude of the photoconductivity of the plasmon-coupled nanoparticles can be tuned independently of the optical characteristics of the molecule, a result that has significant implications for future nanoscale optoelectronic devices.

"If the efficiency of the system could be scaled up without any additional, unforeseen limitations, we could conceivably manufacture a one-amp, one-volt sample the diameter of a human hair and an inch long," Bonnell said.

The study, published in the current issue of the journal ACS Nano, was conducted by Bonnell, David Conklin and Sanjini Nanayakkara of the Department of Materials Science and Engineering in the School of Engineering and Applied Science at Penn; Tae-Hong Park of the Department of Chemistry in the School of Arts and Sceicnes at Penn; Parag Banerjee of the Department of Materials Science and Engineering at the University of Maryland; and Michael J. Therien of the Department of Chemistry at Duke University.

This work was supported by the Nano/Bio Interface Center, National Science Foundation, the John and Maureen Hendricks Energy Fellowship and the U.S. Department of Energy.

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Participants in CHAT (Collaborations: Humanities, Arts & Technology), a digital arts and humanities festival Feb. 16-20, will take part in interactive projects that explore the impact of technology on our lives.

Performances featuring technology also will be part of CHAT, hosted by the University of North Carolina at Chapel Hill and coordinated by its Institute for the Arts and Humanities in the College of Arts and Sciences.

Participants can connect with faculty from area universities and technologists who created the projects and performances. The four-day, five-night festival also will feature discussions and workshops involving faculty, participants and representatives of Research Triangle Park companies.

“The institute has cast a wide net in bringing artists, scholars and practitioners to Chapel Hill for this festival,” said John McGowan, Ph.D., Ruel W. Tyson Jr. Distinguished Professor of the Humanities and institute director. “The festival is a showcase for all the exciting work being done right here in North Carolina, with some national and international figures brought in to spice up the mix.”

Projects will feature work by faculty, technologists and students from UNC, Duke and North Carolina State universities, the Renaissance Computing Institute (RENCI) and academic and corporate partners throughout the region. RENCI, a multi-campus, multidisciplinary research center based in Chapel Hill, brings together experts and advanced technologies to seek solutions to complex problems affecting life in North Carolina.

“Artists and humanists have been both fascinated and a bit threatened by the new ways information is now presented,” McGowan said. “We are in a period of flux, with all kinds of experiments. Especially exciting are the collaborative projects that recognize that digital information is dynamic; that the distinction between producer and audience is breaking down, because the users of information are now able to comment on and revise and add to the materials they are given.”

CHAT is open to the public. Visit http://www.chatfestival2010.com/register.html for registration and fee information. Upon registering, participants will receive advance information by e-mail, all-access passes and times and places for events including the following faculty projects exhibited or performed on the UNC campus:

• “The Virtual Performance Factory”
  A live and virtual simulation of a video game, this project lets audience members move through a performance space and interact with live actors and virtual experiences. Audience members’ actions affect the performance. Game authors will craft narratives for the audience to experience.

  Project Leader: Joseph Megel, UNC, communication studies lecturer and artist in residence.
  Project Team: Allan Maule of Icarus Studios in Cary, liaison and coordinator; Tracy Walker, UNC, project coordinator and research assistant; Rob Hamilton, UNC, communication studies lecturer, technical director and designer; Mark Robinson, UNC, communication studies lecturer and multimedia lab director.

• “The Bathysphere: Motion Capture as Art”
  Designed as a virtual underwater opera and interactive game, the Bathysphere features three-dimensional animations and projections on the walls, ceiling and floor of a space, creating under- and above-water worlds. Two motion-capture systems deployed in the space will enhance the atmosphere: Picking up a beach ball, for instance, will cause an octopus to appear, while waving a wand will direct a school of fish around the space. A sound designer will contribute a musical score to round out the Bathysphere experience. For a demonstration of this project in its early stages, visit http://gazette.unc.edu/file.2.html#chat.

  Project Leaders: Francesca Talenti, UNC, institute faculty arts fellow (spring 2010) and associate professor of communication studies, and Greg Welch, UNC, research associate professor of computer science.
  Project Team: Herman Towles, UNC, senior research engineer in computer science; John Thomas, UNC, senior research associate in computer science; and UNC undergraduate and graduate students in the computer science department.

• “Psychasthenia”
  This project explores the game engine as an artistic medium. An interactive experience Psychasthenia involves custom-made sensors and input devices that govern how a user interfaces with a simulated environment. The project will be displayed and accessed in an immersive dome at RENCI’s UNC site. The dome is a video-projection environment with an ultra-wide field of view (160 degrees) that gives a viewer a sense of total immersion.

  Project Leader: Joyce Rudinsky, UNC, associate professor of communication studies and RENCI chief domain scientist for digital arts and humanities.
  Project Team: Victoria Szabo, Duke, program director of information science and information studies; Mark Robinson, UNC, communication studies lecturer and multimedia lab director; Jason Coposky, RENCI, senior visualization engineer.

• “The Architecture of Association”
  Led by a Duke University research team, this project is a large-scale, generative artwork that draws associative links among media elements to form an evolving visual collage. The Architecture of Association creates rich media landscapes from real-time associative processes. The work will use keywords, metadata and custom clustering algorithms to make selections from the databases, bringing associative material into proximity for a particular duration.

  Project Leaders: Bill Seaman, Duke, professor in the visual studies program; and Daniel C. Howe, Brown University computer science department, digital artist, researcher and doctoral candidate at New York University’s Media Research Lab. To watch a video of the project, click to http://mrl.nyu.edu/~dhowe/video/AoA/.

• “Festival on the Hill,” UNC music department
  The department’s contributions to CHAT will serve as this year’s Festival on the Hill, a department event comprising performances, classes, lectures and more, held every other year. Registering for CHAT will not be required to attend Festival on the Hill events, which will be free to the public. Among offerings, to be detailed in later CHAT announcements, will be an electro-acoustic concert on Feb. 16 and a symposium, “The Art and Culture of the DJ,” Feb. 18-19. For more information, visit http://music.unc.edu/calendars/thecalendar.

  Festival leaders: Stephen Anderson, D.M.A., UNC assistant professor of music; Thomas Otten, D.M.A., UNC associate professor of music; Frances White, freelance composer; Mark Katz, Ph.D., associate professor of music.

• “Then/Now: 3-D Virtual Space as Temporal Telescope”
  An interactive digital world representing parts of downtown Raleigh, this interactive space on a computer screen allows viewers to freely explore the virtual downtown while encouraging them to interact with virtual multimedia kiosks featuring archived images, text and audio of historic buildings, spaces and events. These digital kiosks are strategically placed in the same camera location and orientation as the original archived photos, allowing viewers a chance to both see multimedia displays of the past and participate in a new, virtual space.

  Project Leaders: Patrick FitzGerald and graduate student Melissa Church, N. C. State Advanced Media Lab, College of Design.

• “Internet Archive of African-American Performance Art”
  This project team, comprising a UNC faculty member and his graduate seminar, are creating a Web archive of African-American performance art, featuring an online exhibition to support a variety of media, from texts and photographs to audio, video and Web-based artworks. During a two-week visit to campus in fall 2009, New York performance artist Clifford Owens debuted a performance to be archived on the Web site. Owens is slated to return during the festival.

  Project Leader: John Bowles, Ph.D., assistant professor of art history
  Collaborator: Clifford Owens, performance artist.
  Project Team: Bowles’ graduate seminar.

• “The William Blake Archive”
  This federally funded, free Web site of Blake’s poetry and art is based on approximately 5,500 images (two-thirds from illuminated books and one-third from Blake’s paintings, drawings, and engravings) transferred to digital form. Illuminated books are those in which text is supplemented by decorations such as borders and miniature illustrations. The archive is an international public resource that provides unified access to major works of visual and literary art that are highly disparate, widely dispersed and often severely restricted as a result of their value, rarity and extreme fragility.

  Project Team: Joseph Viscomi, Ph.D., James G. Kenan Distinguished Professor of English and comparative literature at UNC; Robert Essick, University of California, Riverside; Morris Eaves, University of Rochester

Besides these projects, the Carolina Digital Library and Archives in Wilson Library will showcase digital collections. More information is available at http://cdla.unc.edu/index.html?page=portfolio.

Student projects are being chosen and will be announced closer to the festival.

Community members interested in sampling these projects and more are invited to join a tour from 7-9 p.m. Feb. 17, the CHAT Festival Art Walk. To participate, attendees must be registered for the festival. During the art walk, five venues will feature festival projects for observation, and many of the faculty, students and community artists who created the projects will be on hand to meet and greet.

During the art walk, Wilson Library will display faculty projects as well as collections from the Carolina Digital Library and Archives; the UNC RENCI site will feature several inter-institutional faculty projects; student projects will headline an exhibition in the Johnston Center for Undergraduate Excellence; Sitterson Hall, home to the UNC computer science department, will showcase “Avatar” and other demonstrations; and the John and June Alcott Gallery in the Hanes Art Center will feature community art on the theme of video gaming, including conceptual art and drawings from local gaming artists.

CHAT Web site: http://www.chatfestival2010.com

CHAT announcement: http://iah.unc.edu/chat/announcement

Institute for the Arts and Humanities contact on site: Kirsten Beattie, (919) 843-2654,

kbeattie@email.unc.edu

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