Engineers create a sound-powered wireless underwater camera

New York: A team of American engineers has developed a wireless, battery-free, sound-powered underwater camera that is about 100,000 times more energy efficient than other underwater cameras.

The device takes colorful photos even in dark underwater environments and transmits image data wirelessly through the water.

The autonomous camera converts mechanical energy from sound waves traveling through water into electrical energy that powers its imaging and communication equipment.

After capturing and encoding the image data, the camera also uses sound waves to transmit data to a receiver that reconstructs the image.

Because it does not need a power source, the camera can run for weeks without interruption before being retrieved, allowing scientists to search remote parts of the ocean for new species, the team from the Massachusetts Institute of Technology (MIT) in the US said in a paper. published in the journal Nature Communications.

It can also be used to capture images of ocean pollution or to monitor the health and growth of fish raised in aquaculture farms.

“We’re building climate models, but data is missing from over 95 percent of the ocean. This technology can help us build more accurate climate models and better understand how climate change affects the underwater world,” said Fadel Adib, associate professor in the Department of Electrical Engineering and Computer Science and senior author of the paper.

The camera gains energy using “transducers made of piezoelectric materials” that are located around its exterior.

“Piezoelectric” materials produce an electrical signal when a mechanical force is applied to them.

When a sound wave traveling through water hits the transducers, they vibrate and convert this mechanical energy into electrical energy.

“These sound waves can come from any source, such as a passing ship or marine life. The camera stores the collected energy until it accumulates enough to power the electronics that take pictures and transmit data,” the study said.

After the image data is captured, it is coded as bits (1s and 0s) and sent to the receiver one bit at a time using a process called “underwater backscattering.”

The receiver transmits sound waves through the water to the camera, which acts as a mirror to reflect those waves. The camera either reflects a wave back to the receiver or changes its mirror to an absorber so that it does not reflect back.

Although the image appears black and white, red, green, and blue light are reflected in the white portion of each photo.

When the image data is combined in post-processing, the color image can be reconstructed.

The researchers tested the camera in several underwater environments. In one, they captured colorful images of plastic bottles floating in a lake in New Hampshire.

They now plan to improve the device so that it is practical for deployment in real-world settings.