Battery-Free Sensors Underwater with Piezoelectricity

Another example of new ways to add power sources.   I recall piezoelectric methods being suggested as gained from customers walking across a floor.  Harvesting electric power.   Too low power in that case, it turned out.   But it continues to be examined, here underwater.

A Battery-Free Sensor for Underwater Exploration
MIT News  By Rob Matheson
August 20, 2019

Researchers at the Massachusetts Institute of Technology (MIT) have developed a battery-free underwater communication system that uses near-zero power to transmit sensor data. The system makes use of the piezoelectric effect, in which vibrations in certain materials generate an electric charge, along with backscatter, a communication technique that transmits data by reflecting modulated wireless signals off an RFID tag and back to a reader. In the MIT system, a transmitter sends acoustic waves through water toward a piezoelectric sensor that has stored data. When the wave hits the sensor, the material vibrates and stores the resulting electrical charge, which the sensor uses to reflect a wave back to a receiver for decoding. Said MIT’s Fadel Adib, “Basically, we can communicate with underwater sensors based solely on the incoming sound signals whose energy we are harvesting.”  .... '