By Rima Sabina Aouf 

An underwater internet of things monitoring the effects of climate change or sampling waters on distant planets is the dream of a group of MIT researchers who have created a battery-free underwater sensor.

The sensor is part of a communications system that avoids a key problem with underwater electronics, which is the pollution from the use of batteries.

Instead, the sensor harnesses two technologies: for energy, there's the piezoelectric effect, where vibrations in certain materials generate an electrical charge.

And for transmitting data, there's backscatter, which involves reflecting wireless signals back to a reader, and is commonly used in radio frequency identification (RFID) tags.

With these two methods combined, the almost-zero-energy system could operate for a long time with minimal human intervention.