Most smart lock makers need to throw some big ‘ol scare quotes around the ‘smart’ branding, because a lock that remains permanently locked when you forget to charge its battery doesn’t actually seem very smart. But soon, that may no longer be a limitation, thanks to a new chip that lets your lock harvest all the power it needs from the smartphone unlocking it.
If you’ve ever wondered how the invisible near field communication (NFC) chip in your debit or credit card can work for years without ever needing a charge or a battery swap, it’s because it draws all the power it needs to broadcast its short range signal from the chip reader scanning it. It more or less functions like a wireless charger does, using coils of wire and magnetic induction to induce a current from a distance, without needing any physical contact (tap to pay doesn’t actually need that tap).
The limited functional range of NFC (less than four centimeters) and the tiny amount of power transferred by a wireless scanner are the reasons your power-hungry smartphone isn’t charged by NFC, but other devices lacking a giant screen, wifi, Bluetooth, and GPS apparently can be. At least, so long as they only need power at certain moments, like when a lock is unlocking. As The Verge points out, smart locks that draw all the power they need to unlock themselves via NFC have existed for several years now, including iLOQ’s products, but chipmaker Infineon has developed a chip that opens up that functionality up to any smart lock maker wanting to license and embed its hardware.
The Infineon NAC1080 is almost an all-in-one solution, with an integrated ARM Cortex-M0 processor, 128-bit AES encryption, and NFC hardware to both recognize a smartphone and harvest energy from it. The AC energy generated from a nearby NFC-capable smartphone is converted to DC and then used to charge up capacitors that can power tiny electric motors which disengage a simple locking mechanism. In a demo video shared on Infineon’s website, the shackle on a prototype padlock automatically pops open after a few seconds of being in range of a compatible smartphone, with a mobile app displaying an animation of the lock’s internals being quickly charged up. But the performance could vary from device to device, depending on the size and location of its NFC antenna and how effectively it can wirelessly transfer power.
The few seconds it takes to open a smart padlock using this approach doesn’t seem like much of an inconvenience compared to having to remember to charge your lock, but it remains to be seen if a similar approach could be used to power more complex locks with moving parts, like a front door’s deadlock, which requires a big chunk of metal to be completely retracted before the door can be opened. It’s doubtful this solution will seem as convenient if it requires users to hold their phone against a lock for 30 seconds or more to build up enough charge to power the lock’s mechanisms.