3-D Underwater Imaging
Technology inspired by fish could help undersea vehicles find their way

Source: "Artificial lateral line with biomimetic neuromasts to emulate fish sensing"
Chang Liu, Douglas Jones, et al.
Bioinspiration & Biomimetics 5(1): 016001

Results: Drawing inspiration from sensory cells in fish, researchers at Northwestern University and the University of Illinois have created a new kind of underwater 3-D imaging device. The invention uses an array of sensors to detect objects--in this case, a crayfish--on the basis of their movements. It can pinpoint the location of objects within a distance equal to half the length of the array.

Why it matters: The automated underwater vehicles currently used for surveillance, research, surveying, and other applications navigate either with cameras, which don't work well in murky water, or with sonar, which doesn't work well at close range. This new sensor could allow for more accurate navigation, particularly in confined spaces and unclear water.

Methods: Fish detect obstacles, predators, and prey with the help of sensory organs made up of arrays of specialized cells. These cells use tiny hairlike projections to sense water movement. The researchers used microfabrication techniques to mimic these cells. Each artificial sensor consists of a vertical silicon "hair," about 500 micrometers long, that is anchored to a piezoelectric device. As the hair moves, the piezoelectric material generates a voltage. The researchers developed an algorithm that interprets voltage signals from an array of the sensors to locate the source of moving water.

Next steps: The researchers will make larger sensor arrays and attach them to underwater vehicles for practical testing. They will also work to improve the resolution of the sensors so that they can detect objects farther away.