Battery-Free Approach to Ocean Internet of Things

MIT's battery-free underwater piezoelectric sensor transmits data by absorbing or reflecting sound waves back to a receiver.

Prof. Adib holds a PAB Node. (📷: Jimmy Day)

Ice caps are melting, garbage islands are floating, and the surface temperature of the ocean is rising but scientists are still struggling to figure out an effective solution for monitoring the depths of our oceans. Scientists want to get a pulse on how the ocean is changing, and to do this they are currently collecting data using battery-powered underwater sensors. However, batteries can serve as a potential pollutant if they get damaged underwater. A group of MIT researchers is attempting to understand our oceans better without relying on batteries with their innovative battery-free underwater sensors.

What this team of MIT researchers has developed is a radio system that communicates underwater to battery-free sensors using sound waves. A transmitter sends sound waves to submerged sensors equipped with a specialized material called piezoelectrics. The vibrations of the sound wave can be transformed into electrical charge by the piezoelectrics, causing the sensor to power up. Then, these underwater sensors can send binary information to receivers by reflecting existing sound waves. The researchers call this system Piezo-Acoustic Backscatter (PAB).

“Basically, we can communicate with underwater sensors based solely on the incoming sound signals whose energy we are harvesting.” Fadel Adib — founding director of the Signal Kinetics Research Group at MIT.

These battery-free sensors have the ability to be game-changing. A well-established network of these could be used by scientists for more long term data collection. All while limiting the potential environmental issues of putting batteries all over the ocean. Currently, the PAB communication system is limited to about 3 kB/s of accurate data at a distance of 10 meters but they are funded to continue their research and potentially reach their goal of sampling water on Saturn’s moon Titan. I’m excited to see how this technology continues to grow to help monitor the ocean, protect marine life, and prompt social climate change.

Nick Engmann
💻Hacker, ✍️Writer, (🐛)Bounty Hunter, and 🏁Founder —
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