CMU Researchers Find If You Can Paint It, You Can Make It A Touch Screen

May 23, 2017

Touch screens have become part of our everyday lives, but the technology has its limits. They are always relatively flat and are fixed to another product, like a cell phone or a computer.

But researchers at Carnegie Mellon University have figured out a way to make just about any object into a touch sensitive device.

“We extracted sensing techniques from medical fields and things like that,” CMU Human-Computer Interaction Institute Ph.D. student Gierad Laput said. “Very expensive equipment, million-dollar equipment. And we were like, ‘Can we make that cheap?’”

Laput and his co-researchers boiled the sensor down to a few electrodes and a computer chip that cost less than $100.

They figured out that if you put these electrodes on a sheet of carbon-infused plastic used to keep electronics safe from static electricity during shipping, it's possible to send electric pulses among the electrodes.

“You say, ‘Hey electrode one, shoot a signal.' And then all the others receive it and then you go, ‘Electrode two, shoot a signal,’ and all the others receive it," Laput said. "And this happens around 160 times per second.”

When a finger touches the plastic, it changes the way those electric pulses are received and the chip triangulates the location of the touch. The information can be sent to a computer and the computer can be taught to respond just as if it were a touch screen.

But Laput and his colleagues were still limited to sticking sheets of plastic to surfaces, so they started looking for other materials that might work and they found a commercially available spray paint that also is used to insulate electronics from static.

“And so once we figured out that this spray paint can actually have this property, we were like, ‘Oh, now we can spray anything and turn it into a touch screen,'" Laput said. 

And spray they did. A steering wheel was sprayed to add functionality, the body of an electric guitar was sprayed to add musical effects and then, one of the researchers poured Jell-O into a mold shaped like a brain and sprayed that.

“If you touch different parts of the brain we can tell you what part of the brain that is. To me that’s a very good way to teach something,” Laput said. “It’s super tangible as opposed to having it on a flat screen you actually have your brain model and you actually probe it.”

Play-Doh is also slightly conductive and the team found if you sink the electrodes into a sculpture made of the child’s toy, it can become a touch enabled device.

When told about the technology, Marcel Bergerman, co-founder of MySTEM Academy, said it was a huge opportunity to bring technology closer to kids.

“Imagine that every desk, every wall, every part of the floor could be part of an interactive experiment or experience,” Bergerman said.  “Imagine how you could have interactive maps on the wall to teach history or geography and things like that.”

Laput and his team have worked with objects as large as a tabletop and have used as many as 32 electrodes.

“If you go higher than that, the speed at which you can sense goes lower.  It becomes a slower process because there are too many electrodes to go through,” Laput said.  “But if you also go lower, let’s say four, you’re not going to get enough resolution. So there is a sweet spot between those numbers.”

Laput said they're continuing to make the system better and looking for new materials that have the right electrical properties.

In this week's Tech Headlines: 

  • An escalating battle between Apple and Qualcomm over money and patent rights is drawing in Taiwanese contractors that assemble Apple's iPhones. Apple claims that Qualcomm is overcharging for patent-related license fees on iPhone sales, a point Qualcomm disputes. Last month, Apple Inc. began refusing to pay royalties until the courts determine how much it owes, a process that could take several years. According to a federal lawsuit filed by Qualcomm last week, Apple has also instructed its contractors to withhold those payments and has agreed to indemnify them for damages from any lawsuits.
  • The same technology that keeps kids glued to their smart phones is being used by some schools as protection against sexual assaults. Using apps, victims and bystanders can alert school officials, police or parents to trouble. While the systems can be used by kids pranking each other, app developers and school officials say most claims end up being credible. Reporting happens as events unfold and administrators can respond immediately.  The real challenge is money. Not all schools can afford the apps, some of which base their cost on the number of users or size of a student population. However, school insurance companies increasingly are picking up the tab, seeing the apps as a tool to mitigate risk.

The Associated Press contributed to this report.