Feeds

Battery-free e-ink screen grabs screenshots from smartphones

NFC-powered tech useful for those who know they'll forget

Gartner critical capabilities for enterprise endpoint backup

University boffins from Washington and Massachusetts joined forces with those at Intel to create an e-ink screen which can catch a smartphone screenshot – without needing a battery.

The screen catches energy over the NFC standard, the pay-by-bonk technology built into the latest models of smartphone. That power usually drives a cryptographic chip and communicating radio, but the team used it to update an e-ink screen instead.

Regular readers might recollect UK startup PragmatIC doing something very similar back in 2011, and they'd be right. PragmatIC didn’t use e-ink, so the image faded after a few seconds, but it did manufacture the whole thing though a printing process so it was incredibly cheap.

NFC, in contrast to RFID, uses an induction coil in the reader to power a tag. That allows the tag to perform a proper cryptographic authentication, but also provides spare power for hijinks like this.

According to their research paper (PDF, surprisingly readable) the smartphone (filling the role of reader) transmits 200mW of energy: 17.7mW of that gets picked up by the reading coil of which 8.35mW is consumed in processing the NFC communications, leaving 9.4mW to spare*.

That 9.4mW is chucked into a battery (which could be replaced with a capacitor if one wanted a battery-free device, though the difference is debatable) and accumulated for 2.3 seconds, which provides enough power to refresh the e-ink screen.

The mono screenshot mounts up to 5.67KB, so at an average of 13.3Kb/s it takes 3.4 seconds to transmit the image – providing plenty of time to charge up the battery/capacitor.

NFC can ramp up a good deal faster than that, and one could compress the image too, but those would both increase the power consumption of the tag as well as reducing the time available to power it, risking the functionality.

Interesting as the prototype is, there remains the question of why one would want such a thing. Taking a screenshot sounds useful, but a pen and paper would be much more flexible and a good deal cheaper, and who remembers to capture the data before their phone battery goes dead?

It's top boffinry none the less, and the team will be presenting the work at Ubicomp in Zurich next month, but we're hoping that PratmatIC could meet up with (printed e-ink people) Plastic Logic to make a version costing pennies – they're both in Cambridge after all – allowing for a disposable screen for electronic graffiti, though even then it's hard to think of the killer application for such a device. ®

Bootnote

* Yes, we also counted 9.35mW rather than 9.4, but given the complexity of the experiment we're not going to call them on their numbers and will assume it's a simplification issue.

Boost IT visibility and business value

More from The Register

next story
Apple takes blade to 13-inch MacBook Pro with Retina display
Shaves price, not screen on mid-2014 model
iPhone 6 flip tip slips in Aussie's clip: Apple's 'reversible USB' leaks
New plug not compatible with official Type-C, according to fresh rumors
FEAST YOUR EYES: Samsung's Galaxy Alpha has an 'entirely new appearance'
Wow, it looks like nothing else on the market, for sure
YES YES YES! Apple patents mousy, pressure-sensing iVibrator
Fanbois prepare to experience the great Cupertin-O
Steve Jobs had BETTER BALLS than Atari, says Apple mouse designer
Xerox? Pff, not even in the same league as His Jobsiness
TV transport tech, part 1: From server to sofa at the touch of a button
You won't believe how much goes into today's telly tech
Apple analyst: fruity firm set to shift 75 million iPhones
We'll have some of whatever he's having please
Things are looking up in Flappy Bird sequel
'Swing Copters' offers the same gameplay but in a different direction
prev story

Whitepapers

5 things you didn’t know about cloud backup
IT departments are embracing cloud backup, but there’s a lot you need to know before choosing a service provider. Learn all the critical things you need to know.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.
Rethinking backup and recovery in the modern data center
Combining intelligence, operational analytics, and automation to enable efficient, data-driven IT organizations using the HP ABR approach.
Next gen security for virtualised datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.