Transparent touchpad works even when bent and stretched

A close-up shot of a transparent touch panel before filling it with gel electrodes. (University of British Columbia) "KDSPs "A new transparent, flexible touchpad that can feel the touch of a finger even when the material is stretched or bent could help engineers one day create advanced wearable touchscreens," says KDSPE ""KDSPs" are increasingly being developed by researchers around the world for flexible electronic devices such as displays, cameras, batteries and solar panels. These devices could one day be woven into clothing, prosthetics and even the human body, researchers say, "KDSPE" "KDSPs" Previously, scientists developed flexible touchscreens based on carbon nanotubes and silver nanowires, which are only nanometers-a billionth of a meters wide. However, these devices often struggle to work properly when stretched, which includes the materials' inability to distinguish between the touch of a finger and the stretching of the fabric itself. "Ergonomics: 5 Technologies That Bend With You," now, researchers have developed a new, flexible touchpad that can distinguish between touch and stretch. In addition, the device is also transparent, which suggests that it could be combined with a flexible display to form a flexible touchscreen. "KDSPE" "KDSPs" "This is the first time anyone has made a transparent, touch-sensitive electronic device that can detect touch when the device is bent or stretched. John Madden, senior author of the study and an electrical engineer at the University of British Columbia in Vancouver, Canada, said:

The new device is made of hydrogel, which is structured similarly to the material used to make soft contact lenses." When people think of gels, they usually think of them as being soft and weak, like Jell-O, which is intentionally weak so you can chew on it But people have developed these extremely tough gels to replace cartilage, and some of them can be stretched 20 times or more.

By adding salt to an aqueous hydrogel, charged ions can flow through the hydrogel and create an electric field around it. When a finger is near the hydrogel, it interacts with the electric field in a way that can be detected by electrodes attached to the hydrogel. The signals are easily distinguishable from those generated when the hydrogel is bent, the researchers say,

is a close-up of a transparent touchpad before it fills with gel electrodes. (University of British Columbia)

The scientists embedded the hydrogel in silicone rubber. They created a square transparent touchpad about 1.2 inches (3 centimeters) wide with 16 buttons, each about 0.2 inches (5 millimeters) wide.

The array maintains its sensory capabilities even when bent or stretched, and it can withstand common environmental contaminants such as coffee spills. The transparent pad can also detect multiple fingers at once, which is necessary for the zoom feature typically found on smartphones, the researchers said.

The researchers noted that the materials used to make the device cost about $1 per 10.75 square feet (1 square meter) and are inexpensive to manufacture.

"You can put them on pretty much anything," Madden said of the opportunity it offers to make wearables or some kind of robotic skin, or to put it under a carpet to detect someone falling.

In the future, researchers could try to make touchpads that are more durable and stretchable, Madden said. The scientists detailed their findings today (March 15) in the online edition of the journal Science Advances.

Original article in Life Sciences.