Marine and Environment: The Internet of Floating Things

Led by Georgios Sklivanitis, Ph.D.

We investigate the integration of benthic microbial fuel cells (BMFCs) and acoustic backscatter technologies for the development of batteryless subsea ocean IoT. BFMCs take advantage of oxidizing microbes in seafloor sediment to generate a small voltage potential over an extended period of time. We propose using the harvested power from BMFCs to enable intermittent subsea sensor data acquisition. To enable offloading of the data from the subsea sensors to a sea-surface buoy or a data-muling underwater vehicle, we use underwater acoustic backscatter communications. The subsea sensor is integrated with a piezoceramic transducer. By electrically controlling the transducer's impedance, the subsea sensor wirelessly transfers its data by reflecting acoustic signals that are actively emitted by a nearby underwater acoustic transceiver. We established a basic testbed setup in our lab for experimental evaluation of both the BMFCs and the acoustic backscatter communications. For each BMFC, we designed and assembled three modular PCBs, each serving as a different part of the subsea power harvesting and data acquisition system: 1) harvesting and storing power; 2) converting the stored power to a stable voltage output,; and 3) collecting data (e.g., pH, temperature, dissolved oxygen, BMFC voltage). Five BMFCs were configured in a fish tank in preparation for testing the operation of the developed sensor boards. We separately tested different combinations and configurations of ultrasonic hydrophones, transducers, and acoustic speakers to characterize their transmission and reception capabilities with and without preamplification and impedance matching circuitry. Ongoing work includes experimental evaluation of communication range, sensor data acquisition duty cycle, and potential revisions to the PCB designs. After evaluation of power harvesting and communication capabilities in a large water tank, we will proceed with in situ testing in Lake Okeechobee and open ocean environments.