Electrical devices could soon use power make by human energy, Scientists say they have developed an experimental device that produces electricity from the physical movement of a person walking , British scientist Max Donelan and other scientists in Canada and the United States developed the device. The device connects to a person's knee, As the person walks, the device captures energy each time the person slows down, To do this ,the device helps with the slowing sown movement of the leg, The movements of the walking person push parts of a small machine that produces electricity, Using the device, an adult walking quickly could produce thirteen watts of electricity in just a minute, Donelan says walking at that speed could produce enough power to operate a laptop computer for six minutes. There are several possible uses for the device ,Developers say it could help people who work in areas without electricity to operate small computers, The deice could also be used in hospitals to operate heart pacemakers ,It could even be used to assist in the movement of robotic arms and legs. The experimental version of the device weighs about one and a half kilograms, but it is too costly for most people to buy, But the researchers hope to make a lighter, less costly version.An improved version should be ready in one year. The developers hope the device will one day help developing countries, Nearly twenty five percent of people around the world live without electric power. A similar product was invented in 2005 by Larry Rome of the University of Pennsylvania,He created a bag carried on a person's back that also produces power from walking, The knee device does not produce as much electricity as the bag ,But the bag requires the walker to carry a load of twenty to thirty kilograms. From the passage, we can learn that the electrical device can  _  .
help housewives operate the washing machine make it much easier for us to go online produce more electricity than that invented by Larry Rome be applied in medicine to operate heart pacemakers