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Blind fish inspire creation of sensors that detect changes in water pressure
Feng Zengkun Straits Times 14 Dec 12;

A BREED of blind cave fish has inspired new "eyes and ears" for underwater robots and vessels such as submarines.

The creatures, which are found in the caves of Mexico, rely on a strip of sensitive skin on their sides to detect changes in water pressure caused by predators or obstacles.

Scientists at Nanyang Technological University (NTU) have studied them and come up with similar water pressure-based sensors that could help submarines and underwater robots to navigate their environment.

The new sensors are currently undergoing testing in Singapore waters and could be commercialised within two years.

Currently, underwater robots and vessels usually use sonar sensors or cameras to gather data about their surroundings.

But cameras can be thwarted by murky water, while sonar or soundwave technology is expensive and can harm marine life.

Like the cave fish's organic sensors, the NTU invention relies on water pressure changes to locate and identify obstacles.

When swimmers pass each other, for example, they can feel changes in the water pressure on their skin. The NTU sensors work in the same way.

"To mimic nature, our team created microscopic sensory pillars wrapped in hydrogel," said Associate Professor Miao Jianmin, from NTU's School of Mechanical and Aerospace Engineering.

Each sensor is 1.8mm by 1.8mm. They are clustered in groups of 20, with each cluster costing less than $100 to make. They also require little power, meaning they are cheaper and more environmentally friendly than the conventional sensors.

The NTU invention could also be used for defence, as it can detect nearby submarines without using sonar, which gives away the user's location.

Its only drawback is its limited range, since water-pressure changes weaken with distance. The researchers estimated that vessels equipped with the sensors would detect obstacles only less than one body length away.

NTU is working with the Singapore-MIT Alliance for Research and Technology to outfit autonomous underwater vehicles with the sensors, and will present two papers on the work at a prestigious conference next month.

These craft could be fitted with chemical sensors and used to detect pollution in Singapore's waters.