Battery-Free IoT Computing Platform Draws Energy from Air

Several years ago, we told you about how researchers at the University of Washington had developed wireless devices that are powered and communicate solely by harvesting signals from existing television and cellular transmissions in the air. At the time, the technology had interesting implications for sensors, ultra-low-power devices, and other technologies that have since formed the basis for the Internet of Things (IoT).

Fast forward three years and now the research out of UW -- in conjunction with researchers at Delft University of Technology -- has expanded into the development of the Wireless Identification and Sensing Platform (WISP), a mini sensor-based computing platform that can be programmed to create IoT applications.

Electrical engineers from University of Washington’s Sensor Systems Laboratory and Delft University of Technology (TU Delft) have developed a programmable sensing platform that harvests energy from radio waves for electricity rather than uses a battery.
(Source: University of Washington)

“It incorporates sensing, computing, and communication, much like many wearables and IoT devices,” Aaron Parks, an electrical engineering student at UW, told Design News.

WISP’s sensors are powered and read by UHF RFID readers, harvesting power from the RF signal generated by the reader. The platform is an open source, open architecture EPC Class 1 Generation 2 RFID tag that includes a fully programmable 16-bit microcontroller as well as arbitrary sensors, according to information on the website of the UW’s Sensor Systems Laboratory, which is leading the research.

WISP is different than conventional RFID tags, in that the latter are black boxes that cannot execute arbitrary computer programs and do not support sensors. In contrast, WISP is a mini computing platform that can be programmed to create not only sensing-related applications, but also apps in cryptography and security, according to researchers, who have given the platform to collaborators who are developing such applications.

While these characteristics can be found in any computing platform, the real differentiator for WISP is that it doesn’t need a battery to operate. “It does all this with no battery, and is entirely powered by radio waves that we beam at it from somewhere nearby,” Parks said. “Being battery-free means the WISP has an unheard-of life expectancy of many decades, with no need for maintenance.”

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WISP could come in handy for numerous IoT applications, but especially for those in hard-to-access locations where replacing a battery would be difficult or near impossible, Parks said.

“We think the WISP is compelling in any application that’s deeply embedded and hard to get to,” he said. “So for instance, if one wanted to monitor the structural health of a building, one could put strain sensors on the WISP and embed it in the building materials themselves. The embedded WISPs could monitor strains and stresses, and determine when to alert the building's occupants. One could do this kind of continuous monitoring without the need to periodically extract the sensors to replace batteries.”

But while WISP certainly could find its way into niche applications, it also is applicable to any type of system that requires computing and sensing power without the need for long-term maintenance. “It’s also compelling as part of the bigger picture of the Internet of Things, because nobody wants to have to worry about charging or replacing batteries in the hundreds of devices around their home or office,” Parks said.

WISP currently runs on energy harvested from localized RF signals. However, the team’s future research includes exploring how WISP and devices like it can harvest energy for so-called “wild” radio energy -- that is, energy that comes from ambient sources like TV towers and WiFi routers. “We’re hoping to try and answer the question of whether ambient radio energy can power the future of the IoT,” Parks said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 15 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.