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Batteries Built by Viruses What do chicken pox，the common cold, the flu，and AIDS have in common? Theyre all disease caused by viruses，tiny microorganisms that can pass from person to person.Its no wonder1 that when most people think about viruses, finding ways to steer clear of2 viruses is whats on peoples minds. Viruses and batteries may seem like an unusual pair，but theyre not so strange for engineer Angela Belcher，who first came up with5 the idea.At the Massachusetts Institute of Technology in Cambridge, she and her collaborators bring together different areas of science in new ways.In the case of the virus-built batteries, the scientists combine what they know about biology, technology and production techniques. Many batteries are already pretty small.You can hold A.C and D batteries6 in your hand.The coinlike batteries that power watches are often smaller than a penny.However，every year，new electronic devices like personal music players or cell phones get smaller than the year before.As these devices shrink, ordinary batteries wont be small enough to fit inside. How small are these battery parts? To get some idea of the size，pluck one hair from your head.Place your hair on a piece of white paper and try to see how wide your hair ispretty thin，right? Although the width of each persons hair is a bit different，you could probably fit about l0 of these virusbuilt battery parts，side to side，across one hair.These microbatteries may change the way we look at viruses7. | 
