Low-power circuits combined with energy harvesting systems reduce the need for battery replacements or batteries altogether, but they’re traditionally used only for very limited low-power applications. Removing batteries from higher power devices, like those that communicate with cell towers, is a far more complicated challenge, but PhD student Trevor Odelberg and his advisor Prof. David Wentzloff believe it’s possible.
“Cellular IoT is sort of a new field,” Odelberg said. “It wasn’t very suitable to make low-power devices that communicate on the same networks as cell phones, because cell standards are really complicated. However, with new 5G protocols, we’ve started thinking there are ways to lower the power of these devices considerably and potentially influence future standards.”
Odelberg is currently designing prototypes and evaluating ways to alter 5G and future wireless standards so that cellular devices of the future can run directly on harvested energy, no batteries required. For instance, energy can be harvested from heat, light, and vibrations, as well as wireless energy transfer.
“That’s really exciting for us, because 50% of the world, or over 4 billion people, use these standards,” Odelberg said. “It’s not every day that you do something that can impact half the planet.”
Cellular IoT as opposed to more common short-range IoT offers new benefits to the user.
“Cell networks are very secure, very reliable, and very long range,” Odelberg said. “So imagine if you’re doing something like canvassing a smart city or tracking moving objects, such as butterfly migrations, traveling outside the range of a router, you’d want something that can work anywhere but still be low-power.”
From environmental to social applications, hopefully this work will impact people’s lives for the better.Trevor Odelberg
Odelberg’s team is also looking to reduce the power needed to run the hardware so less energy is needed overall, which is needed to eventually run devices entirely on harvested energy. At the 2021 IEEE Radio Frequency Integrated Circuits Symposium, they debuted their dedicated wake-up receiver. This receiver is the first of its kind designed for a cellular IoT protocol and was successful in reducing the overall power consumption.
“We want to be forward thinking with what we’re designing,” Odelberg said. “We know some hardware techniques that can really lower power, and we want to at least predict if not influence the way things are going for wireless communication.”
Going batteryless is crucial for a sustainable future, especially as the number of IoT devices continue to increase. Batteries are a big source of toxic waste, but eliminating them could also help reduce the amount of electronic waste in other ways as well. For example, many IoT devices currently are simply thrown out when their batteries run out.
“These batteryless devices could last for lifetimes,” Odelberg said. “Not only would you not be throwing away batteries, but you wouldn’t have to throw away the old device and replace it with a new one every few years.”
It was this societal impact that initially drew Odelberg to this research.
“The coolest and most important technologies impact people’s lives the most,” Odelberg said. “From environmental to social applications, hopefully this work will impact people’s lives for the better.”
The research was described in “A 2.1mW −109dBm NB-IoT Wake-Up Receiver,” by Odelberg, Jaeho Im, and David Wentzloff. Wentzloff is also co-founder of Everactive, which focuses on advancing batteryless wireless sensor networks for the Internet of Things.