MIT Engineers Create Wireless, Battery-Free Underwater Camera - ExtremeTech:
As of now, a majority of the ocean has gone unprobed. Most of the underwater cameras used to investigate this part of the planet are incredibly unwieldy or expensive to operate: They either wire power from a separate vessel, thus limiting their mobility, or they require battery top-offs from crews on ships. Sending divers into hard-to-reach areas is typically a no-go, too, given the extreme amounts of pressure in places like the Mariana Trench and the deepest corners of the Gakkel ridge. Without the help of autonomous equipment, scientists are left to make educated guesses about what could be hidden in these mysterious places.
MIT's new camera could be exactly the equipment oceanographers and marine biologists need. The engineers started by creating an exterior containing transducers made of piezoelectric materials, or solids that produce electricity under certain mechanical stressors. As sound waves traveling through the water hit the camera, these piezoelectric transducers vibrate, converting mechanical energy into electrical energy. The camera can then use the energy or store it for later.
[...]
Those sound waves could come from any source, like a passing ship or marine life. The camera stores harvested energy until it has built up enough to power the electronics that take photos and communicate data.[...] "We were trying to minimize the hardware as much as possible, and that creates new constraints on how to build the system, send information, and perform image reconstruction. It took a fair amount of creativity to figure out how to do this," Adib says.
[...] Once image data are captured, they are encoded as bits (1s and 0s) and sent to a receiver one bit at a time using a process called underwater backscatter. 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.
A hydrophone next to the transmitter senses if a signal is reflected back from the camera. If it receives a signal, that is a bit-1, and if there is no signal, that is a bit-0. The system uses this binary information to reconstruct and post-process the image.
[...] "This will open up great opportunities for research both in low-power IoT devices as well as underwater monitoring and research," says Haitham Al-Hassanieh, an assistant professor of electrical and computer engineering at the University of Illinois Urbana-Champaign, who was not involved with this research.
Journal Reference:
Afzal, S.S., Akbar, W., Rodriguez, O. et al. Battery-free wireless imaging of underwater environments [open]. Nat Commun 13, 5546 (2022). DOI: 10.1038/s41467-022-33223-x
(Score: 2) by donkeyhotay on Saturday October 01 2022, @12:50AM (2 children)
TFS says the camera has "no battery", but the article also states that the piezoelectric energy can be "used or stored for later". I'm wondering how the electrical energy can be stored if not in a battery.
(Score: 3, Insightful) by coolgopher on Saturday October 01 2022, @01:02AM (1 child)
Probably a supercap would be my guess. We've used that on a design for a very small solar powered sensor device in the past. Really good for low power scenarios where you're mostly trickle charging.
(Score: 2) by donkeyhotay on Saturday October 01 2022, @09:02PM
Yes, of course, a capacitor might do the trick. Thanks for responding.
(Score: -1, Troll) by Runaway1956 on Saturday October 01 2022, @01:05AM (1 child)
I wouldn't be so sure of that. The Navy says that the aliens in tic-tac UFOs are diving into the sea now. Makes you wonder how they can anal probe an octopus, which has no anus.
(Score: 0) by Anonymous Coward on Sunday October 02 2022, @01:18AM
Someone has offended an octoanus, judging by the moderation.