As we reported recently, a breakthrough in touchpad technology has allowed users to draw, read, and even play games on the surface of their own skin. Scientists in Korea developed the “Highly stretchable, transparent ionic touch panel” at Seoul National University, publishing their findings in the latest issue of the journal Science.

The touchpad is built from hydrogel, a network of hydrophilic polymers that allows electronics to operate under stress from stretching and bending. The touchpad can be stretched to as much as 1,000 percent its normal size without losing any functionality. The device is made from a circuit running throughout lithium chloride salts, which creates a current that responds to individual touches.

While the development may seem like a major leap forward, the underlying technology has been around for quite some time. The first touchscreen device, like the majority of mobile phones, was capacitive, rather than resistive. It was found on a radar screen used by the Royal Radar Establishment for air traffic control in the U.K. Interestingly enough, researchers lacked confidence in the technology and delayed developing it for nearly 10 years.

The idea behind a touchscreen is rather simple; using a sheet of conductive, transparent material, a small current passing through creates a static field. When someone touches the screen with their finger, the gap between the screen and the charged plate forms a capacitor. By calculating the change in capacitance at each corner of the screen, the device can tell exactly where the finger is placed.

Touchscreens and touchpads evolved to include resistors, and eventually became incorporated in PDAs and mobile phones. The iPhone revolutionized the technology again in 2007, and touchpads have continued to improve throughout the years, becoming more accurate and responsive.

The newly developed touchscreen applies the lessons of the past few decades using brand new materials that open up all types of possibilities for designers, gamers, and people seeking to interact with their devices in new, innovative ways.

A researcher uses a new, flexible ionic touchpad, placed on his arm, to play video games. This material relates to a paper that appeared in the 12 August 2016, issue of Science, published by AAAS. The paper, by C.-C. Kim at Seoul National University in Seoul, South Korea, and colleagues was titled, “Highly stretchable, transparent ionic touch panel.”

C.-C. Kim et al., Science (2016)