The effects of radiation on over-the-counter electronics are, in contrast,
fairly well known. One of the most important parts of any electronic appliance,
the transistor, is one of the most susceptible components to radiation. The
problem comes from the absorptive properties of the silicon dioxide dielectrics
that insulate a transistor's gate from its semiconductor components. Silicon
dioxide captures radiation, which in turn creates electrons and holes. This
process eventually builds up enough of a charge to short circuit the transistor,
Not only do the human parts of a manned space odyssey need to be protected from
the harsh environs of space, the fragile machinery that carries them will have
to be as well. To address this concern, scientists at Northwestern University
have delivered a new
type of transistor to use in the International Space Station for testing.
The prototype transistors were placed outside the space station where they will
gain unprotected exposure to space radiation for the period of one year.
The transistors are based on a new material, dubbed SANDs for self-assembling
nanodielectrics, and are the product of research into creating new types of dielectrics
for future technology. The Northwestern group's goal was to create a dielectric
material that was not only robust, but printable; something that could be used
in transparent displays or flexible electronics. Ultimately they accomplished
this by utilizing a dipping process to create thin films of self-assembled
Tobin Marks, Vladimir N. Ipatieff Research Professor of Chemistry at the
Weinberg College of Arts and Sciences and Professor of Materials Science and
Engineering at the McCormick School of Engineering and Applied Sciences
explains, “It’s not just that these transistors are only good for outer space
-- that’s an illustration of just how tough they are. There is one technology on
Earth, and only one, that will create as many features per unit time as a chip
plant, and that’s a modern newspaper printing plant, since the paper flies at
hundreds of feet per second. Every time Intel wants to make a new chip, it
costs billions of dollars and takes years to do. And yet every day they print a
new New York Times. So we thought,
could you use printing to create electronic circuits?”
Preliminary tests with nuclear reactors show promising results for the SANDs.
They appear to be highly resistant to radiation exposure, so NASA has taken a
keen interest. Should the ISS tests return favorable results, the new material
could revolutionize space electronics in terms of endurance and lifespan.
Aside from the obvious benefits in being radiation resistant, the group hopes
to see the new material find use in many other fields -- wherever flexible,
hardy and printable circuitry could find itself utilized. Some examples they
cite range from solar panels to cell phones to flat-panel displays. One goal is
to create inexpensive RFID tags to compliment or replace bar codes in stores.
Cashiers could more easily interact with the tags, scanning an entire cart's
contents at once along with alerting her if an item has reached its expiration
date or informing her and the computer if the item is low on stock levels.
While the Northwestern group has already succeeded in making printed circuitry
using their new material, they continue to research transistor materials that
can be used as inks. The combination of a printable transistor with a highly
durable dielectric substrate will likely lead to some very nifty electronics in