nanotech (was: Rachel's #772: The Revolution, Pt. 1)

Les Schaffer schaffer at optonline.net
Wed Aug 13 13:39:34 MDT 2003


Mike Friedman forwarding Rachel's newsletter:

> Nanotech is now the third largest federal research project, just
> below the war on cancer and the star wars missile defense
> shield. (See the NNI web site at www.nano.gov.) The largest federal
> research subsidy for nanotech ($221 million) goes to the NSF itself
> and the second-largest ($201 million) to the Department of
> Defense.[3]

i've noticed nanotech research beginning to gain market share in
science and engineering journals for a while now. Cornell, one of my
alma mater's, built a large, expensive nano lab back in the 90's.

on scientific grounds, the work is absolutely fascinating. as to
technical possibilities, ditto. but i've read somewhere -- maybe
emails from Andy Coates offlist??? -- that the small particles used in
these facilities is not great for the human lung and otherwise.

while the trumpets are blaring louder for the wonderful things we can
do to clean arteries with nano-artery-scrubbers, etc. i've been
wondering for a while what are the real forces behind current nano
production upsurge.

shortly after Mike's article arrived, i received my weekly mailing
from the American Inst. of Physics. Sure enough:

      DETECTING PLASTIC EXPLOSIVES IN AIR at the parts-per-trillion
      level has been achieved by researchers at Oak Ridge National
      Laboratory and the University of Tennessee [snip], potentially
      leading to a fast, portable, and ultrasensitive plastic-bomb
      "sniffer."  Plastic explosives such as pentaerythritol
      tetranitrate (PETN) and hexahydro-1,3,5-triazine (RDX) pose
      serious threats because (1) they are easily to mold into desired
      shapes, (2) they remain highly stable until detonated, and (3)
      they can inflict significant damage even in small amounts. In
      fact, the infamous shoe bomber had PETN in his footwear.  Most
      current plastic-bomb sensors are bulky and expensive.  In
      contrast, the new sensor is a microelectromechanical system
      (MEMS), or a tiny mechanical device with microscopic dimensions.
      Potentially cheap and easy to mass-produce, the bomb-sniffing
      MEMS device is a microcantilever, a 180-by-25-micron slab of
      silicon attached to a spring-loaded wire.  Similar in structure
      to a diving board attached to a pool, the microcantilever is
      coated on one side with gold.  On one end of the gold-coated
      surface is a single layer of 4-MBA (4-mercaptobenzoic acid), to
      which PETN and RDX both attach.  Like hair that curls up on a
      humid day as water molecules adsorb to it, this specially coated
      cantilever will bend by significant amounts when PETN and RDX
      molecules attach to it.  A laser-microscope system can detect
      the degree of bending to nanometer precision. Placed in a
      vacuum-tight glass cell, the cantilever was exposed to a stream
      of ambient air with tiny traces of plastic explosive.  Using a
      modified atomic force microscope to measure the deflections of
      the cantilever, the researchers determined that their MEMS
      device could detect the explosives at a level of 14 parts per
      trillion, after only 20 seconds of operation. By another
      measure, the device becomes sensitive to plastic explosives even
      if only a few femtograms (1 fg=10^-15 g) impinges upon it.  A
      future step is to take the device out of the laboratory and
      develop it into a portable sensor. While much activity has
      centered on the development of sensors for detecting vapors from
      all kinds of explosives, this is, to the authors' knowledge,
      only the third device of its kind that uses MEMs.  (Pinnaduwage
      et al., Applied Physics Letters, 18 August 2003)

though i don't mean to imply all nanotech work is military/defense in
nature, we can expect much of the initial outlays of R&D capital to
issue from the defense funding spigot.

les schaffer





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