The prototype autoclave consists of a concave mirror that focuses sunlight into a container of water to activate nanoparticles to convert solar energy directly into steam. It was developed by Rice University graduate student Oara Neumann (left) and Dr. Naomi J. Halas. (Photos courtesy of Jeff Fitlow and Oara Neumann, Rice University)

2013-9-10 | News Americas

INDIANAPOLIS, USA: Last weekend, chemists from the U.S. presented a novel device for sanitizing medical and dental instruments. According to the researchers, the device does not need electricity or fuel to turn water into steam and could be of great benefit for practitioners and hospitals in developing countries in particular.

According to Dr. Naomi J. Halas, lead researcher and professor of biomedical engineering, chemistry, physics and astronomy at Rice University, about 2 million people worldwide do not have access to a regular supply of electricity. While autoclaves usually rely on electricity to produce steam to sterilize instruments, doctors in such regions often have to use chemicals for sterilization, which can be costly and pose transport difficulties.

With the use of solar energy, however, the researchers hope to provide an effective alternative. The autoclave works with metallic nanoparticles that are placed inside a container of water. Sunlight quickly heats the nanoparticles and a layer of steam forms and buoys them up to the water's surface. They release the steam and sink back into the water to repeat the process.

Preliminary tests showed that the prototype autoclave produced steam at temperatures ranging from 239 to 270 degrees Fahrenheit. The scientists reported that steam production adequate for sterilization was reached within 5 minutes and continued long enough to sterilize liquid and solid materials inside the device.

In addition to the sterilizing autoclave, the researchers have developed an autoclave for disinfecting human and animal waste, another major source of disease transmission.

The technology was first unveiled by Rice University scientists about one year ago. The prototype autoclaves are its first practical application. Halas recently formed a company that is working on moving the devices from the prototype stage to commercialization. 

The findings were presented at the opening of the 246th National Meeting and Exposition of the American Chemical Society, a nonprofit organization that provides chemistry-related information through databases, journals and conferences. The meeting is currently being held at the Indiana Convention Center in Indianapolis.