How to sterilise scalpels when no electricity is available

IN THE HISTORY of medicine, praise is rightly showered on those who invented vaccines, antibiotics, antiseptics and anaesthetics. Few, though, remember Charles Chamberland, inventor of the humble autoclave. Yet the ability to sterilise surgical instruments reliably, by exposing them to high-pressure steam in such a device, has been crucial to the development of modern surgery. A mere 12 minutes in an autoclave at 121°C and two atmospheres of pressure kills 99.99% of common pathogenic bacteria. Standard boiling, at 100°C and one atmosphere, takes 80 hours to achieve that level of bactericide.Electrically powered autoclaves have, as a consequence, become so routine as to be almost unregarded—at least in those places with a reliable electricity supply. Where electricity is not reliable, though, it can be hard to keep surgical instruments germfree. This is a problem to which Zhao Lin of the Massachusetts Institute of Technology thinks he may have an answer. As he and his colleagues describe in , they have designed an autoclave that is powered directly by sunlight. And not only that; they also reckon it should cost just a tenth as much to make commercially as a conventional autoclave of equivalent potency.