Battery-free IoT devices around the corner?

Energy consumption and battery life are key issues for IoT devices.

I’m seeing a lot of devices these days that claim to have very long battery life. For example, garbage bin sensors made by companies like Enevo and SmartBin claim to have unbelievable battery life of about 10 years. On the component front, I wrote in the past about Adesto’s CBRAM memory that consumes 1/100 less energy and Spansion’s new line of sensors that can harvest it’s own energy from the sun, heat, and vibration.

However powering the connectivity aspect is still an unsolved issue. Yes, we are seeing new generations of Bluetooth and Wifi modules that consume much less energy than a decade ago, but they still guzzle much more energy than sensors. Even if other components ration or harvest their own energy, IoT devices will one day run out of energy and stop transmitting data.

Well, that may change.

I came across a very interesting news this week from the University of Washington about a technology called “Wifi backscatter” that can transmit data to PCs and smartphones by utilizing wifi radio waves flying around in the air already.

スクリーンショット 2014-08-07 13.49.11

So here’s a summary of how it works from reading their white paper. Hope I’m correct!

  • There already is a technology to harvest energy from radio waves in the air such as TVs, cell phones, wifi, etc.
  • However, energy harvested from radio waves is not enough to power the wifi module (order of 3-4 magnitude insufficient)
  • To solve this problem, Wifi backscatter does not rely on a wifi module, but attempts to transmit data by utilizing wifi signals flying around already.
  • Wifi backscatter can reflect or not reflect wifi signals flying between the router and the PC/smartphone. This reflection can be detected by the PC/smartphone as fluctuation in signal strength. This fluctuation can be used to represent data.
  •  Encoded data from the IoT device gets transmitted as fluctuation in wifi signal and decoded by the PC/smartphone.

Quite a nifty technology indeed. They say they’ve accomplished transmission rate of 1kbps with about 2m between the devices, which can be enhanced to about 20m in the future.

Obviously this technology has a long ways to go and will need to face privacy and security issues before it gets commercialized. Nevertheless it’s still great to see technology developments pushing the envelope of IoT’s potential.

Check out the full scan of the IoT sector with more than 500 companies here.

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