Electrical & Computer Engineering Seminar
Underwater Communication and Sensing at Near-zero Power
Sayed Saad Afzal
PhD Candidate, Massachusetts Institute of Technology
Abstract: This talk presents Piezo-Acoustic Backscatter (PAB), the first technology that enables backscatter networking in underwater environments. PAB relies on the piezoelectric effect to enable underwater communication and sensing at near-zero power. Its architecture is inspired by radio backscatter which works well in air but cannot work well underwater due to the exponential attenuation of radio signals in water. PAB nodes harvest energy from underwater acoustic signals using piezoelectric interfaces and communicate by modulating the piezoelectric impedance. Our design introduces innovations that enable concurrent multiple access through circuit-based frequency tuning of backscatter modulation and a MAC that exploits the properties of PAB nodes to deliver higher network throughput and decode network collisions. We built a prototype of our design using custom-designed, mechanically fabricated transducers and an end-to-end battery-free hardware implementation. We tested our nodes in large experimental water tanks at the MIT Sea Grant. Our results demonstrate single-link throughputs up to 3 kbps and power-up ranges up to 10 m. Finally, we show how our design can be used to measure acidity, temperature, and pressure. Looking ahead, the system can be used in ocean exploration, marine life sensing, and underwater climate change monitoring.
Bio: Sayed Saad Afzal is a PhD candidate at the Massachusetts Institute of Technology. His research interests focus on developing innovative, low-cost, and low-power distributed sensor technologies and systems for applications in climate monitoring, environmental sustainability, and food security. More specifically, Saad is currently researching ocean sensor technologies that rely on acoustic backscatter, a technique that enables communication with 1 million times less power than existing systems. He recently used this technology to build the world’s first battery-free underwater camera, enabling long-duration monitoring in remote ocean locations. He has also used these sensors to monitor essential indicators such as biodiversity and carbon balance. Saad has already made notable technological contributions with implications for climate monitoring, food security, and ecology, and his future work has tremendous potential to advance sensor technologies supporting innovative research and a sustainable future.
Wednesday, Oct 18, 2023, 4pm
Via Zoom: https://clarkson.zoom.us/j/99689458746?pwd=eVowa1RleDRwdWNNT1pyUS82eUpmdz09
*Co-Sponsored by IEEE student branch and HKN