Autoclaves for sterilizing medical instruments in hospitals require a constant supply of compressed steam at a temperature of about 125°C. In many developing countries, electricity is not available for these purposes. MIT has created a device that sterilizes medical instruments without the need for electricity.
A team of researchers from the Massachusetts Institute of Technology and the Indian Institute of Technology has come up with a way to passively generate the required steam using only the energy of sunlight, without the need for fuel or electricity. The device, which requires a solar collector of approximately 2 m² to power a typical small clinic autoclave, will provide access to safe, sterile equipment at low cost in remote locations. The prototype was successfully tested in Mumbai, India.
The key to the new system is the use of an optically transparent airgel. The material is a lightweight silica foam and consists mainly of air. This lightweight material provides effective insulation, reducing heat loss tenfold.
The airgel is glued to the top of the solar hot water production equipment. It consists of a copper plate with a heat-absorbing black coating. When the sun heats up the plate, the water flowing through the pipes beneath it takes that heat away. But with the addition of a transparent insulating layer on top and polished aluminum mirrors on each side of the plate, the system generates high temperature steam instead of just hot water. At the end of the process, steam under pressure is fed into the autoclave.
Much of the developing world faces limited availability of reliable electricity or affordable fuel, which is necessary for autoclaving or medical sterilization. The new development will help solve this problem, scientists are sure.