What it really takes to make a flexible phone (Smartphones Unlocked)

A bendable screen is nice in the lab, but it will take more than flexi-glass to get your phone to touch its toes.

Jessica Dolcourt Senior Director, Commerce & Content Operations
Jessica Dolcourt is a passionate content strategist and veteran leader of CNET coverage. As Senior Director of Commerce & Content Operations, she leads a number of teams, including Commerce, How-To and Performance Optimization. Her CNET career began in 2006, testing desktop and mobile software for Download.com and CNET, including the first iPhone and Android apps and operating systems. She continued to review, report on and write a wide range of commentary and analysis on all things phones, with an emphasis on iPhone and Samsung. Jessica was one of the first people in the world to test, review and report on foldable phones and 5G wireless speeds. Jessica began leading CNET's How-To section for tips and FAQs in 2019, guiding coverage of topics ranging from personal finance to phones and home. She holds an MA with Distinction from the University of Warwick (UK).
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Jessica Dolcourt
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Watch this: Bend it like Corning Willow Glass

Had Dipak Chowdhury known just how accident-prone I really am, he never would have handed over the 0.1-millimeter sheet of glass for me to bend between my fingers.

Luckily for me, the vice president and director of Corning's Willow Glass division is a trusting soul and gave CNET the world's very first public demo of this glass so thin it can bend without breaking.

Flexible glass and flexible screens have been a hot topic for some time, culminating with fanfare at Samsung's demo of its curvy Youm OLED display at CES.

Companies like Samsung, Nokia, and even Apple have been working on flexible smartphone displays for a years, but for the first time, there's enough real research and development in this area to, perhaps, start getting excited.

Just think of what a bendable smartphone could do: curve with your body's movement so it sits more comfortably in a pocket; drop from a height and flex on impact, rather than shatter; pack into any number of compartments without having to triple-swath it in bubble wrap.

But don't get too frothed up yet. Willow Glass isn't the hearty Gorilla Glass 3, Samsung's Youm screens have nothing to attach to yet, and smartphones that sway in the breeze are still years out.

There's more that needs to go with the flow than just the display and its glass.

The problems with flexible glass

One of the biggest challenges with a flexible phone is getting the cover glass to bend -- and it's a common misconception that bendable glass is unbreakable.

Corning's Chowdhury stresses that Willow Glass was designed as a substrate material -- glass that belongs on the inside of a smartphone -- but in its current form, it isn't strong enough to serve as the tough barrier guarding the internal materials from the elements. It wasn't designed to be.

Yes, a substance similar to the bowed Willow Glass could undergo a similar chemical strengthening process as Corning's more famous Gorilla Glass, the substance that makes up the outer layer protecting many of today's phones, tablets, and laptops.

However, even if a Willow Glass cousin does grow fortified enough to top a phone and maintain its bend, breakage is still a worry.

When chemists and industrial designers talk about strength, they're not just talking about massive cracks and shattering. It is true that flexible glass can withstand drop tests with less damage than some rigid glass, thanks to its undulating ways, but it may not be able to rebuff the scratches, gouging, and long-term wear patterns that make screens vulnerable to breaks.

Though Corning's current Willow Glass formula can deeply arch, it can still also puncture and snap.

What about a plastic screen instead?

It's very possible that the first actively bending displays we see will be covered by plastic rather than glass. As always, resilience and durability are concerns.

"There will be a compromise there," said Mark Rolston, chief creative director of celebrated firm Frog Design. "It's a material reality that anything that conforms will be more susceptible to scratches."

Corning's Chowdhury notes that some companies have demoed an arching plastic display for several years, but that there's still a long road to commercialization, even for the polymer.

The fact that the smartphone industry has almost wholesale moved from plastic screens to glass is also telling -- you don't see a plastic Retina Display on the iPhone 5S, after all. Images look sharper and clearer with a glass cover, and it's also more responsive and sensitive to touch. (I've reviewed touch-screen phones without glass covers, and the experience was pretty terrible.)

Glass is also better at being impermeable to oxygen and water, two compounds you want as far from a phone's electronic guts as possible, to keep them from damage and aging.

If we do see bendable designs with plastic screens, they'll likely top reference products and concept designs, or very early niche models, rather than mature, mass-market devices.

Batteries don't flex well

Even if you get the screen technology and the glass to flex, there's still the matter of the other internal components. What do you do about the battery, the processors, the camera module, and the NFC circuitry -- all currently static wafers, bricks, and chips?

LG battery
Today's conventional batteries work best as a brick. LG

Conventional lithium ion batteries, which power today's smartphones, are very rigid, says Marc Juzkow, vice president of research and development for battery company Leyden Energy. They need to be stiff and unyielding in order to last the longest time possible.

New battery technology in early development is moving in the direction of the thin, flat cell, but these aren't the right solution for a bendable phone, either, Juzkow says. First, they use a solid-state electrolyte to generate power-yielding reactions, and that takes longer to charge. Second, their energy output isn't enough to run a power-hungry phone for very long.

In case you're wondering, it would in fact be possible to place a thicker, shorter battery to one end of a device, Juzkow concedes, so that the phone flexes while the battery does not. Makers of small flexible products, like smartphones, could also insert a series of smaller batteries along the length, leaving room for the device to bend between these static slugs. There's just one major problem with the latter: smaller batteries generate less charge and die off faster than larger batteries.

That doesn't mean a flexible phone is out of the question. Mechanical and design engineers have worked with shaped batteries and flexible printed circuit boards before, even though both are generally rigid.

Flexible printed circuit boards for example, were at one time ubiquitous in the humble flip phone, connecting both halves of the clamshell as it folded.

Read also: Emerging battery tech hopes to make smartphones last longer

As for shapely batteries, one only need to look to Nike's FuelBand for a hint of recently broken ground. In making the device, Nike placed two curved batteries on either side of the band, covered by a piece of metal that restricts that portion of the band from bending.

It may be that the flexible phone of the future comes with some premolded elements.

Seeking the Lycra of phone chassis

When thinking about a bendable phone, there's also the problem of the phone material itself. From a design perspective, you don't want the body to be too lax or too rigid, says Rolston, Frog Design's creative lead.

"You have to build in limits. You can use a flexible plastic, but can [the body materials] also stop the movement at the end of the flex?"

In other words, if the phone bends, will it snap back to its original shape. There is such a thing, it turns out, as a phone that is too flexible.

One good example of what's possible and what might actually come, is Nokia's "kinetic device," a working prototype of a lightly twistable handheld computing device that CNET reporter Stephen Shankland saw in London in 2011.

Beyond its screen, you can manipulate the entire device, adjusting the sides in order to scroll through content like music and photos.

Shankland reported that some of the devices Nokia demoed that day contain carbon nanotubes in an elastomer material, a specific type of rubbery polymer. Stressing one side of the device while compressing the other created the physical interaction to make images advance and music to forward.

The ideal material for a flexible smartphone or other device bends slightly without losing its original upright form over time, a sort of Lycra for the personal electronics world.

"The question is the memory of the material," says Robert Curtis, Frog Design's executive director of product development. "How much does it hold if it's bent or unbent?" Memory, in this case, refers to the material's ability to return to its original shape, the antithesis of memory foam.

The good news is, all the materials to make this possible already exist. The difficulty is in assembling all the pieces into a functional design.

Then there's the price

Ask Corning's Dipak Chowdhury one of the main benefits of Willow Glass and he'll tell you that because it can be made it in a roll, it's cheaper to manufacture.

Yet the cost of making a single component less expensively doesn't add up to a product that's cheaper overall. The research, development, sourcing, and manufacturing process for new materials doesn't happen overnight, and can wind up being pretty pricey for a new technology.

How much would the average consumer pay for a bendable phone? Sure, it's a neat idea, but after the novelty wears off, how practical would a bendable phone really be compared with a traditional stick-straight device? Put another way, how much extra would you pay for your phone to conform to the shape of your pocket?

Forget the phone rollup, 'bent' will triumph over 'bending'

There's one shape we can cross off the list when drafting the flexible smartphone of our dreams: a device that rolls up into a circle or a scroll.

A rolled-up handset is "a really stupid idea," says Mark Rolston, Frog Design's creative director.

"Rolling and unrolling a phone defies the behavioral element of a phone," he added, stating that people want to pull their device out of your pocket and use it right away.

Flexible phones and other devices may have a place in the world, but Rolston thinks they won't show up until the bending of glass and other components is "really mature."

Corning's Chowdhury agrees, partly because vendors haven't zeroed-in on what they want. "We're trying to commercialize our glass," he said, and when it comes to a fully functioning device, "there's no agreed-upon term for what 'flexible' means." Without that firm definition, there's also a foggy path to how vendors plan to profit from phone flex in their designs.

Instead of bending for the sake of it, both the glass and marketing executives see conformable displays finding much broader applications at first, before we start seeing commercial uses for those flexible bodies and screens. Premolded glass structures defy the straight, flat rectangle comprising so many panels in TVs, cell phones, and pretty much every programmable screen, and displays that take on organic shapes and configurations have any number of uses: perhaps futuristic computers that form the walls of your office, or a car windshield you can program to show you a map while you drive.

Between Rolston and Chowdhury, there are plenty of other examples that we can expect in the near future across a variety of industries, some of which we already see budding today:

  • Wrap-around screens for devices and trade-show booths
  • Curved displays for sports accessories, like watches and home appliances
  • Formed displays for car dashboards
  • Toys, thermostats, and tools that read out measurements
  • Flexible photovoltaic cells for solar paneling you can unroll on a roof

These ideas may not be widely seen today, but they aren't new. In 2008, Rolston said, Frog Design created a prototype design for HP with a wrap-around screen. It was decorative, rather than for informative, he said, but it made the sides of this mystery device integral in the never-released project's shape.

Rolston, for one, keeps coming back to the car dashboard, waxing poetic in the charming way that designers do about the aesthetically driven "humanistic" form of a sculpted car dash and the effort that designers put in to create luxury finishes using metal, wood, and carbon fiber.

"In the middle of all that," Rolston laments, "we increasingly cut an 8-inch rectangular hole to put a screen. If we can have that screen instead be part of the material, part of the car's visual language...that would be a beautiful thing."

"God, that'd be cool."

And perhaps that's the major lesson that bendable screens can teach us at this stage in their development. To be cool, you've got to be flexible.

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Smartphones Unlocked is a monthly column that dives deep into the inner workings of your trusty smartphone.