- Solar-powered autoclave sterilizes medical instruments
HOUSTON – To help solve a long-standing health issue for developing
countries, students at Rice University are using the sun to power an autoclave that
sterilizes medical instruments.
The engineering students used Capteur Soleil, a device created
by French inventor Jean Boubour, to use solar energy in locations where electricity
– or fuel of any kind – is hard to obtain. By attaching an insulated
box that contains the autoclave, the students have transformed the device into a
Capteur Soleil resembles an ultramodern lawn swing, with a steel
A-frame spine and a bed of curved mirrors beneath the frame that focus sunlight
along a steel tube at the frame’s apex to produce steam. Rather than pump
steam directly into the autoclave, the Rice students decided to use the steam to
heat a custom-designed conductive hot plate.
When the hot plate reaches 121 °C – the standard set
by the Centers for Disease Control and Prevention – for 30 minutes, the contents
within the autoclave should become sterile. Within half an hour of receiving strong
sunlight, the Capteur Soleil will begin to produce steam, which will then heat the
patterned hot plate and then the FDA-approved autoclave. With good midday sun, the
students said it takes about 40 minutes to an hour to begin significant heating
of the autoclave.
With a steamer basket and medical instruments inside, the autoclave
is wrapped in silicon-based Thermablok insulation, which has the highest R-value
of any known material and is a spinoff from NASA research into thermal protection
for the space shuttle.
To check the system, the team used some biological spores from
a test kit, steamed them and then incubated them for 24 hours. The tools came back
negative for biological growth, meaning that whatever was in them was killed in
“This is really the latest iteration of a much larger project,”
said Doug Schuler, the team’s faculty adviser and an associate professor of
business and public policy at Rice’s Jones Graduate School of Business. “We
already have a version of the Capteur Soleil being used in Haiti for cooking, but
we felt it could do more.”
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