The coating that makes iPhones touch sensitive is running out

Fjord_iPhone Screenshot 3

No, iPhone screens are not magic. They are coated in a transparent material called indium tin oxide that senses when a finger makes contact.

ITO comes from the metal indium, which must be mined. Prices are rising as it becomes more scarce; the U.S. government estimates that from 2010 to 2011, the cost for indium rose by 25 percent. The world could run out altogether in the next decade.

To keep costs down, electronics manufacturers will need to look to alternative materials. At the Semicon West conference Wednesday in San Francisco, industry experts reported on potential alternatives such as carbon nanotubes and silver nanowires that could someday become the dominant touchscreen coating.

During his presentation, Nanotech Biomachines CEO and CTO Will Martinez presented the audience with a transparent sheet covered in graphene — an emerging material made of a one-atom-thick layer of carbon atoms. He bent it back and forth to demonstrate its flexibility.

“Try this with ITO and ITO would be filled with cracks,” he said.

Rahul Gupta, senior director of business development at Cambrios Technologies, touted the features of his company’s silver nanowires. Nanowires can be any length but are 10,000 times skinnier than a human hair.

Unlike many emerging materials, silver nanowires are already used in a few laptops, e-ink devices and smartphones. But while the materials are cheap, processing them is not. He showed that silver nanowires and metal mesh, another alternative, can hit a “sweet spot” for transparency and conductivity. Silver nanowires have already been tested in a bendable e-ink display, when a display was bent 100,000 times without an impact on performance.

“It’s rock solid, steady,” Gupta said.

Gupta said requirements are changing for touchscreen coatings. They must now rival or top ITO in transparency and conductivity, plus be flexible and able to conform to curved surfaces. Meeting those requirements will be especially important as manufacturers adapt materials to the coming wave of wearable electronics and even 3D TVs.

Demand for touch sensitive devices is growing quickly, meaning manufacturers are racing to produce widely adopted ITO alternatives within the next few years. According to Cambrios, 1.4 billion smartphones will have touchscreens, compared to 531.9 million today. While far fewer laptops will have touchscreens, the demand for laptop touchscreens measured in square meters will soon rival phones. There will be 20 million square meters of laptop touchscreens by 2015, compared to 35 million square meters on phones.

Some manufacturers are already planning on incorporating ITO alternatives into their devices. Foxconn might begin using carbon nanotubes in the non-Apple devices it makes by the end of 2013, and Samsung is working on prototypes that use graphene, according to Martinez.

“There’s lots of R&D to be done though,” Martinez said.

This story was updated at 12:40 a.m. on July 12 to remove the word “metal” from the title. While the coating is partially made from metal, it is not itself a metal.

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