http://www.theharrowgroup.com/articles/20020415/20020415.htm#_Toc6321551 Dust In The Wind.
Investigating Nano.
Supporting our growing number of discussions on "things nano" (such as at
http://www.theharrowgroup.com/articles/20020401/20020401.htm#_Toc5165660), reader Kimberly Allen who earned her PhD on "Buckyballs," the precursors to carbon nanotubes, points us to what she considers "the authoritative site on nanotube science." It's the work of Professor David Tomanek at Michigan State, and the site carries a vast number of links to the world of the very tiny -
http://www.pa.msu.edu/cmp/csc/nanotube.html .
I believe that keeping up on ever-faster changing and evolving technologies such as nanotechnology is vitally important to our individual successes, and to the successes of our businesses. Here, reader Roger Williams offers his perspective on the criticality of "looking ahead at change."
"Change will always happen. The rate of change, the second derivative, makes it more difficult to judge just how that change might affect my own decisions. The time between needed decisions, if you will, has changed markedly, and in order to make rational decisions about change, I want a view that reaches farther into the future.
The Harrow Report ... helps me get that longer-range view. It is not to say that your reports necessarily have to be true to the last syllable, it is the drift that is important. Informed prognostication is valuable; it raises the chances that you are a) right and b) have a reasonable and useful comment. And that in itself becomes useful.
Thanks very much for the work you do."
Dust In The Wind.
To Kimberly's point, "Dust in the Wind" is a phrase with some romantic cachet, ranging from the hauntingly beautiful song by that name from Kansas (
http://hurl.content.loudeye.com/scripts/hurlPNM.exe?clipid=007503901020006550&cid=600100 and
http://members.tripod.com/kansasfreak/dustwind.mid), to NASA's Stardust probe that is collecting samples of the dust wafting in the interstellar wind that originates in the hearts of stars (
http://science.nasa.gov/headlines/y2000/ast24apr_1.htm).
But if work being conducted at the University of California Berkeley and in other labs comes to fruition, the "dust in OUR wind" won't be stardust -- it will be made up of cubic-millimeter sized computer dust motes containing power supplies, processors, sensors, and laser and radio-based networking capabilities! These dust motes will create vast interconnected "computers" that sip energy at the infinitesimally small rate of picoJoules per bit. (Yes, these days even the term "nano" isn't small enough -- "pico" (10E-12) is three orders of magnitude smaller than "nano!" (10E-9))
Brought to our attention by reader Victor Panlilio, the April 5 EETimes (
http://www.eet.com/story/OEG20020405S0015) describes how such "smart dust" could be scattered over a battlefield by a high-flying unmanned aircraft, or mixed into house paint, or even "...swallowed with your breakfast cereal for health monitoring."
Image - Conceptual block diagram of Smart Dust and some of its potential uses.
http://www.sfgate.com/cgi-bin/objec.../archive/2000/11/20&type=science (click on the picture for a larger version)
Conceptual block diagram of, and uses for, Smart Dust.
From
http://www.sfgate.com/cgi-bin/artic...0/11/20/MN62513.DTL&type=scienceThis work is still in the "macro" test bed stage, but it holds fascinating potential for "changing the rules." (Additional insights are available in the April 9 ZDNet.com article "Computing With A Pinch of Sand" at
http://zdnet.com.com/2100-1103-879388.html.)Overall, according to Yury Gogotsi at Drexel University (
http://www.philly.com/mld/philly/business/technology/2975921.htm),
"Nanotechnology allows you to do things that are impossible in the macroscopic world. Among the expected breakthroughs are order-of-magnitude increases in computer speed, enormous advances in health science, and the ability to create 'designer' materials [by] assembling atoms and molecules."
And, of course, by assembling Smart Dust.
Consider this opportunity -- if Smart Dust DOES become prevalent, there might be an emerging market for personal vacuum systems, and for exceptionally good air filtration systems for our homes and offices, just to keep the dust, and its intrusive oversight, at bay!
Hummm. Perhaps if all this does come to pass, we might find the smart dust getting in our eyes! Then, er, I guess I'd have to change my message to -- "DO Blink!"...
One more link:
http://chem-faculty.ucsd.edu/sailor/research/smartdust.htmlTARGETED SMART DUST
HOW IT WORKS:
In order to spontaneously assemble and orient the micron-sized porous Si "smart dust," we couple chemical modification with the electrochemical machining process used to prepare the nanostructures. The process involves two steps, see the scheme below. In the first step, a porous photonic structure is produced by etching silicon with an electrochemical machining process. This step imparts a highly reflective and specific color-code to the material, that acts like an address, or identifying bar-code for the particles. The second step involves chemically modifying the porous silicon photonic structure so that it will find and stick to the desired target. In the present case, we use chemistry that will target the interface between a drop of oil in water, but we hope to be able to apply the methodology to pollution particles, pathogenic bacteria, and cancer cells. The two steps (etch and modify) are repeated with a different color and a different chemistry, yielding two-sided films. The films are broken up into particles about the size of a human hair. With the chemistry shown below, the particles seek out and attach themselves to an oil drop, presenting their red surface to the outside world and their green surface towards the inside of the drop.
Once they find the interface for which they were programmed, the individual mirrored particles begin to line up, or "tile" themselves on the surface of the target. As an individual, each particle is too small for one to observe the color code. However, when they tile at the interface, the optical properties of the ensemble combine to give a mirror whose characteristic color is easily observed. This collective behavior provides a means of amplifying the molecular recognition event that occurs at the surface of each individual particle.
As a means of signalling their presence at the interface, the particles change color. As the nanostructure comes in contact with the oil drop, some of the liquid from the target is absorbed into it. The liquid only wicks into the regions of the nanostructure that have been modified with the appropriate chemistry. The presence of the liquid in the nanostructure causes a predictable change in the color code, signalling to the outside observer that the correct target has been located. This work was first reported in J. R. Link, and M. J. Sailor, Proc. Nat Acad. Sci. 2003 100, 10607-10610.
Cartoon of smart dust
Image:Artist's conception of how encoded porous Si "Smart Dust" particles might be used to detect chemicals in the field.
NANOSTRUCTURED "SMART DUST" CHEMICAL SENSORS. The objective of this effort is to construct sensors for chemical or biological molecules that use no power, are the size of dust particles, and can be probed at a remote distance using visible or infrared laser scanner technology. The particles are made of porous silicon, and they are constructed with of an elaborate layered structure that gives the materials photonic crystal properties. To use them as chemical sensors, the porous nanostructure is chemically modified so that its code changes in a predictable fashion when it is exposed to chosen molecules. Detection of volatile organic compounds (VOCs) was demonstrated in T. A. Schmedake, F. Cunin, J. R. Link, and M. J. Sailor, Adv. Mater. 2002, 14, 1270-1272.
HOW IT WORKS: Nanoscale holes in the porous matrix act as concentrators, condensing vapors of the analyte. Catalytic reactions take place in small micellar nanoreactors, converting the analyte into a chemical that can be recognized specifically by the matrix (see J. Am. Chem. Soc. 2000, (22), 5399-5400). The particle has a layered structure that provides an optical code, much like a barcode, that can be read by a remote laser beam. The reactions in the nanoreactors change the code in a predictable fashion, providing a signal that scales with dose. In the example shown in the image, the catalytic reaction is chosen to detect G-type nerve warfare agents, such as Sarin (the agent used in the Tokyo subway attack perpetrated by the Aum Shinrikyo cult).
UCSD PRESS RELEASE
QUICKTIME MOVIE OF POROUS SILICON PHOTONIC CRYSTAL SENSOR (CHIP-BASED SYSTEM):
--(3.4 Mb) [download]
Discover Magazine article
More Info...
Image: Microscopic image of porous Si "Smart Dust" particles encoded with two different colors. These particles, each roughly the size of a human hair, can be used in applications designed to rapidly screen for new drugs or genetic markers for disease. SILICON "SMART DUST" FOR HIGH THROUGHPUT SCREENING. The objective of this effort is to construct particles that contain distinct codes. The particles are made of porous silicon, and they are constructed with of an elaborate layered structure. This gives the materials photonic crystal properties; only very specific wavelengths of light are reflected from them. These specific wavelengths are like a code that can be read with a laser or an optical spectrometer, similar to how a bar code is scanned at a grocery store checkout counter. Use of these encoded materials in biological screening applications appeared in F. Cunin,T. A. Schmedake, J. R. Link, Y. Y. Li, J. Koh, S. N. Bhatia and M. J. Sailor, Nature Materials 2002, 1, 39-41. They may also be useful as non-toxic tags, or tracers, for a variety of forensic or environmental applications.
