The number of connected devices is forecast to expand significantly in the next few years as the IoT grows in scope.
As a result, the technology that enables these objects to communicate and sense each other will need to be developed differently than current states.
Because of this, researchers at Purdue University and the University of Virginia have developed a new fabrication method that makes tiny, thin-film electronics circuits peelable from a surface. The process eliminates several steps in the manufacturing process along with the associated costs but also allows objects to sense their environment or be controlled through the application of a high-tech sticker.
"We could customize a sensor, stick it onto a drone and send the drone to dangerous areas to detect gas leaks, for example," said Chi Hwan Lee, Purdue assistant professor of biomedical engineering and mechanical engineering.
Today’s electronic circuits are individually built on their own silicon wafer, which can withstand high temperatures and chemical etching that are used to remove the circuits from the wafer. But these processes damage the silicon wafer, forcing manufacturers to use an entirely new wafer each time.
How They Did It
Purdue’s technique, called “transfer printing,” cuts these manufacturing costs by using a single wafer to build a nearly infinite number of thin films holding electronic circuits. Instead of using temperature and chemicals, the film can peel off at room temperature simply with the help of water.
“It’s like the red paint on San Francisco’s Golden Gate Bridge – paint peels because the environment is very wet,” Lee said. “So in our case, submerging the wafer and completed circuit in water significantly reduces the mechanical peeling stress and is environmentally friendly.”
A ductile metal layer is inserted between the electronic film and the silicon wafer allowing the peeling process possible using water. The thin-film electronics can then be trimmed and pasted onto any surface, granting that object electronic features.
If a sticker was placed on a flower pot, it would be capable of sensing temperature changes that affect the plant’s growth. The researchers also used one film to turn on and off an LED light display. The electronic stickers could turn ordinary children’s blocks into a high-tech sensor device connected to the internet of things.