The advent of electronic paper and efforts to embed electronics
in nontraditional materials like clothing, is spurring efforts to make
The challenge is that, silicon, the mainstay of computer chips,
is quite brittle. Some researchers are turning to flexible plastics for
a solution, but plastics don't conduct electricity very efficiently. Researchers
from the University of Illinois at Urbana-Champaign are looking to solve
the problem the other way around -- they have found a way to make flexible
circuitry from high-quality silicon.
The method involves making tiny silicon ribbons, stretching a
rubber sheet, apply the ribbons to the sheet, then releasing the sheet.
When the rubber contracts, the silicon ribbons form regularly-spaced ripples.
Subsequent stretching and compressing of the rubber causes the ripples
to flatten out or bunch up. The ripples allow the ribbons to stretch without
the silicon being strained.
The researchers have made diodes and transistors from the stretchy
silicon ribbons; testing showed that the components' electronic properties
did not vary when they were stretched or compressed.
The method could be used to build electronic devices on flexible
materials like fabric and irregularly shaped objects like toys.
(A Stretchable Form of Single-Crystal Silicon for Electronics
on Elastomeric Substrates, Science, published online December 15,
Photos make icons meaningful
Staring at a screenful of identical icons is not the most efficient
way to find the file you are looking for.
Researchers from Northwestern University are looking to remedy
the problem with a system that automatically generates semanticons
-- image-based file icons that are easier to find and remember than ordinary
The system analyzes file names and the contents of files to generate
keywords that are then used to query a database of stock photographs.
It identifies appropriate photographs, uses the photograph as a template
to create simplified cartoon images, and places one or two of the images
on an icon template based on file type. A semanticon for a Web page containing
a news article about Java software, for example, combines an image of
a stack of newspapers with an image of a cup of coffee on a template for
HTML file icons.
Users recognized semanticons an average of 1.96 seconds faster
than ordinary icons and performed a memory game more than 20 percent faster
using semanticons than ordinary icons, according to studies by the researchers.
Semanticons could make it easier for users to find and organize
The work builds on the concept behind a system developed last
year for generating graphical icons based on file names. (See Automatic
icons organize files, TRN, September 8/15, 2004)
(Semanticons: Visual Metaphors as File Icons, Computer Graphics
Forum, September 2005)
Info theory boosts clustering
The emerging field of clustering aims to help scientists analyze
mountains of data like genome sequencing, astronomical observations and
market behavior by automatically grouping like pieces of data.
Princeton University researchers have taken a fresh
approach to the clustering problem using information theory to generalize
the process, which removes the need to define ahead of time what makes
pieces of data similar to each other.
The method determines how much information each piece of data
has in common regardless of the nature of the information, and it boils
down to finding the best trade-off between maximizing the apparent relatedness
of pieces of data while minimizing the number of bits needed to describe
The method can be used with any kind of data and performs better
than previous clustering algorithms, according to the researchers.
(Information-Based Clustering, Proceedings of the National
Academy Of Sciences, December 20, 2005)
Lasers drive biochips
Pumping and channeling tiny amounts of liquids in biochips is
Biochips use microscale channels to transport and combine chemicals
and fluids carrying cells and other biological materials; this is useful
for biological research, medical diagnostics and drug discovery. Researchers
have developed a variety of methods for moving and steering the fluids,
including networks of electrodes, and tiny pumps and valves.
Researchers from the University of California at Berkeley and
the University of California at San Francisco have devised a simple, low-power
transportation technique that involves suffusing a liquid with gold
nanoparticles and using a low-power laser to guide the liquid through
the channels of a biochip.
Due to the coffee ring effect, the gold nanoparticles concentrate
at the outer edges of the liquid, near the boundary between the liquid
and the air. The laser heats the nanoparticles, which causes the surrounding
liquid to rapidly evaporate. The vapor rapidly cools and condenses in
the air, forming droplets on the channel surfaces beyond the boundary
of the liquid. As the droplets grow, they combine with the body of the
liquid, effectively moving the liquid. Moving the laser beam moves the
liquid with it.
The technique promises simple, lower-power biochips.
(Optofluidic Control Using Photothermal Nanoparticles, Nature
Materials, published online December 18, 2005)
Bits and pieces
makes tiny amounts of delicate radiological labeling chemicals; a design
for combining nanoscale components promises powerful encryption chips;
of electrical wires built into walls and ceilings makes it possible
to place lights anywhere in a room.