Category: Nanotechnology

Gina Miller writes "AScribe reports on March 14, 2002 Using 'Nature's Toolbox,' DNA Computer Solves Complex Problem; Molecular Technology May One Day Outstrip Computers. Leonard Adleman, computer science professor at USC famed for his 1994 demonstration that DNA could be used for computation, has now used a DNA based computer to solve a logic problem (a 20-variable instance of the NP-complete three-satisfiability (3-SAT) problem) that required an exhaustive search of more than a million possibilities. Unlike the simple problem solved by his 1994 demonstration, which could easily be solved by a human with pencil and paper, no human could solve this problem without the aide of a computer. Although the current massively parallel DNA computer could not match the performance of a modern electronic serial computer, it could have advantages in certain situations. "We've shown by these computations that biological molecules can be used for distinctly non-biological purposes," Adleman said. "They are miraculous little machines. They store energy and information, they cut, paste and copy." For another approach to computation with DNA, see the Nanodot post from 23 November 2001."

The media drumbeat touting molecular electronics as the first likely wide-scale applications of nanotechnology is getting louder:

• An article in EE Times ("Researchers close to delivering molecular circuits", by Chappell Brown, 15 February 2002) says "Although it's a little like watching a chess match in slow motion, molecular electronics researchers are converging on viable circuit-fabrication methods. Several approaches to building circuits with molecules reached the stage of at least rudimentary logic or simple devices, such as inverters or AND gates, last year."
• The looming advent of nanoelectronics was also highlighted at this yearís annual meeting of the American Association for the Advancement of Science (AAAS) in Boston, 14-19 February 2002. A press release from the AAAS (14 February 2002) says "A landslide of discoveries brought the promise of powerful electronic and computing devices, built at the molecular scale, to the forefront of scientific research in 2001. In particular, several research teams hooked up tiny devices such as transistors, wires, and switches to form working circuits for the first time", and describes the many advances by researchers in the field in the past year. "We may be five to six years ahead of schedule in nanoelectronics, and some of today's research is nearing the stage where it could be turned over to industrial production . . . It's been a momentous period for nanoelectronics, with more in store for the future," said James Ellenbogen of the Mitre Corporation. In December 2001, the editors of the journal Science, which is published by the AAAS, highlighted the field of molecular electronics as this yearís "Breakthrough of the Year" in a special issue of the journal (20 December 2001).
• More coverage of the molectronics buzz at the AAAS meeting was provided by an article from the Atlanta Constitution ("Science gathering predicts a big future for small tech", by Mike Toner, 15 February 2002) that appeared on the Small Times website. Recent advances in molectronics, Toner writes, are "the harbingers of a new epoch" that "might make it possible to develop a generation of nanorobots that could fight disease on a molecular level, biochemical sensors that could detect a single anthrax cell and computer storage devices that could pack the contents of the Library of Congress in the space of a sugar cube. . . . One by one, researchers are marshalling the building blocks of a market the National Science Foundation estimated could grow to $1 trillion and employ 2 million people over the next 10 to 15 years." The article also quotes nanotech researcher Charles Lieber, a Harvard chemistry professor and winner of the 2001 Foresight Feynman Prize for Experimental work: "A year ago, I wasn't sure that the achievement of a complex integrated nanosystem was possible. Now I think it is a distinct possibility in the near future."

from the Molectronics dept.
The cover and a pair of feature articles in the February 2002 issue of Materials Today, an international magazine devoted to the latest research and policy news for materials researchers in academia, industry and government, highlight "Molecular electronics: the future of computing". The two feature articles are available on the MT website, as Adobe Acrobat PDF files. (Note: the PDF files have been print-disabled, so you can only view the articles online.)

• "Introducing molecular electronics" by Mark Ratner. This article introduces the basic concepts of molecular electronics, looks at the promise that molecular electronics holds, and describes the fundamental questions that still have to be answered for these promises to be fulfilled. Ratner, a Professor of Chemistry at Northwestern University, was one of the visionary co-inventors of the concept and scientific study of molecular electronics. He was awarded the 2001 Feynman for Theoretical Work at the Ninth Foresight Conference on Molecular Nanotechnology in November 2001.
• "Moletronics: future electronics" by Kwan Kwok with DARPA and James Ellenbogen of MITRE Corp. This extensive and well-illustrated article surveys recent work in the field of molecular electronics.
• "Nanowires take the prize" (not available online) is a news item and interview of Charles Lieber, a molecular devices researcher at Harvard who was awarded the 2001 Feynman Prize for Experimantal Work. "We have these things as chemical or building blocks there to be manipulated. You can combine things that you just didnít think you could combine. You can bring functionality to the table that really isnít possible by other means," says Lieber.

waynerad spotted an item in Electronic Engineering Times ("Towards the single molecule transistor", by Nolan Fell, 24 January 2002) that provides a brief update on work by Bell Labs' physicists Hendrik Schön and Shenan Bao, who report they have developed a FET combining both insulator and semiconductor layers within a single organic molecule. "The combination of insulating and semiconducting parts could lead to true single-molecule transistors," said Schön. "We need now to develop a more complex molecular design and connect them to some kind of contact." A technical report appeared in the 14 January 2002 issue of Applied Physics Letters. Earlier Nanodot posts on the Bell Labs molecular transistors appeared on 17 December and 8 November 2001.

Vik points to an article in Technology Research News ("Morphing DNA makes motor", by Kimberly Patch, 16 January 2002) on the research by Nadrian Seeman at New York University into DNA-based devices:

"Dr. Nadrian Seeman has created and tested a 4-step DNA motor that can rotate indefinitely. Fuelled by other DNA strands, the molecular motor described in [the] TRN article operates in controllable steps. Dr. Seeman says that the range of motion is from 0.04 to 4 nm, although movement of 35nm has been made using arrays of the devices."

This item was also reported here on 2 January 2002.

from the great-minds-think-alike dept.
Adam Burke writes "I recently read this account of Thomas Edison describing utility fog, and thought it may appeal to Foresight members, who share his enthusiasm for technology:

Edison had spoken one day at dinner

. . . as if out of a great revery, saying what a great thing it would be if a man could have all the component atoms of himself under complete control, detachable and adjustable at will. "For instance," he explained, "then I could say to one particular atom in me – call it atom No. 4320 – 'Go and be part of a rose for a while.' All the atoms could be sent off to become parts of different minerals, plants, and other substances. Then, if by just pressing a little button they could be called back together again, they would bring back their experiences while they were parts of those different substances, and I should have the benefit of the knowledge."

This originally appeared in an article in Harper's Magazine (issue 80, 1890) by George Lathrop, and is recounted in Paul Israel's 1998 biography of Edison."

from the World-Watch dept.
A paper presented by M.C. Roco at the symposium on Global Nanotechnology Networking, at the International Union of Materials Meeting, 28 August 2001, gives a high-level view for the potential for international cooperation and coordination of nanotechnology research and development efforts. The paper, "International Strategy for Nanotechnology Research and Development", which previously appeared in the Journal of Nanoparticle Research, is available as a MS Word (.doc) file (about 110 Kb). Roco is Senior Advisor for Nanotechnology at the U.S. National Science Foundation (NSF) and Chair of the U.S. National Science and Technology Council's subcommittee on Nanoscale Science, Engineering and Technology (NSET), the coordinating body of the U.S. National Nanotechnology Initiative.

from the Go,-Huskies! dept.
According to a press release (29 November 2001), a team of researchers under Viola Vogel, director of the University of Washington's (Seattle) Center for Nanotechnology, have developed a new technique for observing large proteins that gives scientists the most detailed picture yet of the biological workhorses in action and promises to shed light on a wide range of protein functions, particularly in settings of medical interest.
"To a large extent, a protein's structure determines its function," said Vogel. "But, for very large proteins, the precise correlation is poorly defined. Now we have a very efficient way of tracking changes in structure so we can see how it relates to what these large proteins do."

from the current-events dept.
Adding to the recent spate of advances in molecular electronics research, two important papers on the use of carbon nanotubes to form electronic devices and circuits appeared in the 9 November 2001 issue of Science.

• Cees Dekker and co-workers at the University of Delft in the Netherlands report they have demonstrated logic circuits with field-effect transistors based on single carbon nanotubes. The transistors show favorable device characteristics such as high gain, a large on-off ratio, and room-temperature operation. The team was also able to demonstrate one-, two-, and three-transistor circuits that exhibit a range of digital logic operations, such as an inverter, a logic NOR, a static random-access memory cell, and an ac ring oscillator.
• Charles Lieber (recipient of the 2001 Feynman Prize in Nanotechnology for experimental work) and his research team at Harvard report a "bottom-up" approach in which functional device elements and element arrays are assembled from solution through the use of electronically well-defined semiconductor nanowire building blocks. Crossed nanowire junctions and junction arrays can be assembled with controllable electrical characteristics. The junctions can be used to create integrated nanoscale field-effect transistor arrays with nanowires as both the conducting channel and gate electrode. Nanowire junction arrays have been configured as OR, AND, and NOR logic-gate structures with substantial gain and have been used to implement basic computation.

Additional details is available in an article from the New York Times ("Nanowires May Lead to Superfast Computer Chips", 9 November 2001) and an item on the Nature Science Update website ("A little logic goes a long way", by Philip Ball, 9 November 2001). And Charles Lieberís work was the focus of an article in the November-December 2001 issue of Harvard Magazine ("Liquid Computing", by J. Shaw).

from the Getting-wired dept.
An extensive article on the Small Times website ("UCLA team develops molecular switches", by Jayne Fried, 26 October 2001) describes recent work by James Heath and his coworkers at the California NanoSystems Institute (CNSI) to develop working molecular electronics devices. According to the article, they have have attached molecular switches on a grid as small as 50 nanometers, a significant step forward in the UCLA effort to build a rudimentary molecular computer. "There's a long way to go," Heath said. "Right now we have circuits with molecules on a grid on normal lithographic wires." The goal is that one day the grid would be assembled with carbon nanotubes. More information on the molectronics work at UCLA can be found in Foresight Update #44.