A new stretchable transparent touchpad can be used to write words and play electronic games, and may even one day be implanted inside the body, its inventors say.
Touchpads and touchscreens are on nearly every smart device these days. But they can’t go on anything flexible, such as the human body. Scientists have explored stretchable touch panels based on carbon nanotubes, metal nanowires, and other advanced materials, but the performance of these stretchable touch panels fell off sharply when they were stretched.
Ref: Highly stretchable, transparent ionic touch panel. Science (12 August 2016) | DOI: 10.1126/science.aaf8810
Because human-computer interactions are increasingly important, touch panels may require stretchability and biocompatibility in order to allow integration with the human body. 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. The panel can be operated under more than 1000% areal strain without sacrificing its functionalities. Epidermal touch panel use on skin was demonstrated by writing words, playing a piano, and playing games.