In medical settings such as hospitals and clinics, the equipment used to sterilize medical instruments need a dependable supply of pressurized steam at a temperature of about 125 degrees Celsius. The source of the steam is usually electricity driven or fuel-powered boilers. However, in many rural areas, especially in developing countries, electricity can be undependable or unavailable, and fuel is expensive.
In a bid to address this, a team of researchers at the Indian Institute of Technology and MIT have come up with a method for passive generation of the required steam. The method uses the power of sunlight, and does not require electricity or fuel. Using solar power, the sterilizing equipment would require a solar collector of about 2 square meters to provide energy for a small clinic-size autoclave. Such an apparatus can maintain safe, sterile equipment at significantly low cost in rural locations.
The apparatus is described in a paper published in the journal Joule.
Use of thermally insulated material makes the system effective
In fact, the key element of the system is optically transparent aerogel. The material is developed over the last few years led by a research associate at MIT. Essentially, the material is a lightweight foam composed of silica and contains mostly air. And, being light, effective thermal insulation of the material reduces rate of heat loss by ten times.
To serve functional purpose, the insulating material is attached on the top of commonly used equipment for producing solar-powered hot water. Typically, this off-the-shelf equipment comprises a copper plate with a heat-absorbing black coating, attached to a set of pipes on the underside. As the plates are heated with solar energy, the water flowing underneath absorbs the heat.