New technology could herald an age when touch pads could be integrated into our bodies.
You may think you’ve seen everything when it comes to touch pads — but you haven’t seen anything like this. Researchers have created a wearable touch screen panel that you can actually stretch, and it can be used to write words or play games.
This thin, flexible touch pad is highly transparent and can be pulled onto your arm. It is made of hydrogel, or a network of hydrophilic polymers. And even when the touchpad is stretched to 1,000 percent of its normal area, it still operates. The paper describing the technology was published in the journal Science.
The hydrogel contains lithium chloride salts, which behave as a conductor to retain water. After 100 cycles, resistance was found to increase slightly, which means that there may be some water evaporation in the gel.
“Transparent touch screens, from large-panel interactive information maps to advanced cell phones, have become a part of daily life,” the paper’s abstract states. “However, such devices all use hard materials. Kim et al. have developed a soft touch panel based on polyacrylamide hydrogels (cross-linked polymers swollen with water) that are highly transparent and contain trapped LiCl to enhance conductivity. The hydrogels are soft and can be stretched extensively while still maintaining touch sensitivity.”
How does it work? Essentially, a circuit is closed in the hydrogel when a finger touches a panel, and current flows from both ends of the strip to the touch point.
“Because human-computer interactions are increasingly important, touch panels may require stretchability and biocompatibility in order to allow integration with the human body,” the abstract continues. “However, most touch panels have been developed based on stiff and brittle electrodes. We demonstrate an ionic touch panel based on a polyacrylamide hydrogel containing lithium chloride salts. The panel is soft and stretchable, so it can sustain a large deformation. The panel can freely transmit light information because the hydrogel is transparent, with 98% transmittance for visible light. A surface-capacitive touch system was adopted to sense a touched position.”
This technology could be incredibly useful, enabling “biocompatibility” and integration with the human body at some point, calling to mind a futuristic world like in Minority Report where touch screens are everywhere.
“Using the touchpad, they were able to draw a stick figure, with the data conveyed onto a computer screen,” according to a statement from the American Association for the Advancement of Science. “With the thin touchpad placed on their arms, they were able to write words and to play the piano and games. The touchpad was still able to operate when it was stretched to more than 1000% of its normal area. After 100 cycles the resistance was found to increase slightly, which the authors suggest may be due to water evaporation in the gel.”