Solar sterilizer

The portable device uses solar energy to sterilize medical equipment

By Donna Lu

The solar sterilizer during the tests

MIT News

Sterilized equipment is not always available for medical professionals performing operations in remote areas of the world. Now a portable, solar-powered device can generate enough high-pressure steam to sterilize medical instruments in resource-constrained areas.

Lin Zhao of the Massachusetts Institute of Technology and his colleagues have developed a device that can power an autoclave, a machine used to sterilize medical devices through effective pressure cooking.

The new tool also works in cloudy or cloudy conditions. It consists of a solar component that heats water to create steam, which is then connected to a pressure chamber.

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“One of the major challenges in using this type of device to provide pressure and steam above 100 ° C is that these devices lose heat to the environment,” says Zhao.

With this in mind, an airgel – a solid, foam-like material – made from silica is a key component of solar heating. The gel is completely transparent, so it doesn’t hinder the absorption of sunlight, but acts as an insulator to prevent heat loss.

To be effective at sterilizing equipment, autoclaves must maintain a temperature of at least 121 ° C and a saturated steam pressure of at least 205 kilopascals for 30 minutes.

In a field test in Mumbai, India, researchers set up a prototype and showed that it can successfully generate steam at 128 ° C and 250 kPa. They estimate that it generates 260 watts of energy.

When exposed to sunlight, the solar heating took about 10 minutes to heat the water to the temperature and pressure conditions required for the autoclave.

The researchers estimate that one of the solar units produces 260 watts of energy, which is not enough to power the 60 or 100 liter autoclaves normally used in operating theaters. “All you have to do is connect more of our solar modules to provide enough heat,” says Zhao.

Journal reference: Joule, DOI: 10.1016 / j.joule.2020.10.007

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