Engineers have built a new type of gadget that doesnt look like most others. Its stretchy， thin and so light that a human hair can lift it. Its made from cheap， nontoxic materials. It can also vanish. After a month in acid — even just kitchen vinegar — the device is gone.

Ting Lei， a chemical engineer who works in the lab of Zhenan Bao at Stanford University in California， helped design the innovation. To demonstrate the new technology， Lei and his team built a stretchy transistor. A transistor controls the flow of current in electronics. The scientists used iron to build the conducting part of the device. Iron occurs naturally， and it wont cause harmful pollution when the device breaks down.

However， building the circuit wasnt the hard part. The researchers had to find some material that could both hold the circuit together and later fall apart in acid.Two years ago， they came up with a recipe. They began making a polymer out of imines （IH-meens）. These are chemical compounds held together by double bonds between carbon atoms and nitrogen atoms. The bonds stay strong in water， but fall apart in acid. An imine polymer was perfect for Lei and his team.

The last piece of the puzzle was a material to hold the whole device together. The researchers used cellulose. This is the fibrous stuff in plants and trees （and used to make paper）.The team put all of those pieces together to make the first electronic device that can break down into environmentally friendly components. The researchers also showed that the device could conduct electricity.

Electronics that break down can help solve a growing problem. Worldwide， people add around 41 million metric tons of electronic waste to landfills every year. And that amount is growing. But if a device dissolves， it wont add to the problem.endprint