Students Chin Jung Cheng, Charlie Matlack, Penny Huang
and Jacqueline Linnes designed a way to know when water left in
a plastic water bottle in the sun is safe to drink (Photo:
University of Washington)
The worldwide shortage of clean drinking water is a serious
problem, although in many cases there’s a relatively simple
solution – just leave the tainted water outside in clear plastic
bottles, and let the sun’s heat and ultraviolet rays purify it.
This approach is known as
SODIS (SOlar DISinfection of water in plastic bottles), and
it removes 99.9 percent of bacteria and viruses – results
similar to those obtained by chlorine. Unfortunately, however,
there’s been no reliable way of knowing when the water
has reached a safe level of purity. Now, four engineering
students from the University of Washington have created a
simple, inexpensive device that does just that... and they won
US$40,000 in the process.
The UW
students took part in a contest promoted by
InnoCentive Inc., a company that hosts a website where
organizations post technical challenges, and anyone can send in
their solutions for a chance to win cash prizes. In this case,
the nonprofit
GlobalGiving Foundation had asked other nonprofits around
the world to submit their water-related challenges, from which
it chose five to post on InnoCentive – the
Rockerfeller Foundation supplied the prize money. The
challenge the students took up had been submitted by the
Bolivia-based
Fundación SODIS, a nonprofit group that promotes the use of
SODIS in Latin America.
The students, Chin Jung Cheng, Charlie Matlack, Penny Huang
and Jacqueline Linnes, developed a simple device using parts
from a keychain that blinks when exposed to light. When attached
to a water bottle, it monitors how much light is passing through
the water. An indicator light blinks on and off as long as
particulates are still obstructing the light flow, and stops
blinking once the water is safe to drink. It is also able to
tell when a bottle of water is present in front of it, so it’s
not trying to measure data when nothing’s there.
It is estimated that parts for each device would cost about
US$3.40, although bulk buying should push that figure even
lower. Matlack described it as containing “all the same
components that you'd find inside a dirt-cheap solar calculator,
except programmed differently.”
Fundación SODIS now holds a non-exclusive license to develop
the technology, although a donor from the foundation has offered
Matlack US$16,000 to do so himself. Along with Linnes and
another student, he is now setting up a nonprofit business
called PotaVida
to produce and promote the water bottle indicator, and is
looking for industry partners to add their expertise.
“We're at a point where we recognize the need for work on
this beyond engineering,” he said. “Ultimately, the hardest part
is going to be to get people to use it.”
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