Computer touchscreens are nearly ubiquitous on laptops, tablets and smartphones. But those are often made of glass or plastic, which is heavy, inflexible and even breakable. Now there's a way to make them out of paper, which is lightweight, flexible and cheap. Use of paper touchscreens could extend from electronic devices to to nutritional labels and price tags.
The paper, created by a team of researchers led by Aaron Mazzeo, a mechanical engineer at Harvard, starts with a process already used to make shiny labels for beer bottles: Paper is coated with a very thin layer of aluminum, which is then covered in a thin film of transparent polymer.
Aluminum conducts electrical charges. Putting two sheets of the metallic paper next to each makes a capacitor, a device that stores an electrical charge. With the aid of an external circuit, the metallized material becomes a surface that can detect charges. When a person touches the paper layer, the amount of charge in the paper goes up — just like it does on a glass or plastic touchscreen.
To create a keyboard, the researchers used a laser to etch cuts into the metal-coated paper.
The paper is quite cheap, about 25 cents per square meter, which means a nine-digit keypad the size of those on a calculator could be made for a few cents. The next step is making electronics and power sources that are similarly low-cost. At that point one could imagine cardboard boxes with electronic locks.
The work was published in the journal Advanced Materials.
Credit: Aaron Mazzeo et al.