Scientists at Georgia Tech have developed an underwater sensor based on the ability of blind fish to navigate in caves. See <http://www.laboratoryequipment.com/news-flow-sensors-based-on-fish-hair-032509.aspx>.
Mark Minton Fish Hair Inspires Flow Sensors March 25, 2009 A blind fish that has evolved a unique technique for sensing motion may inspire a new generation of sensors that perform better than current active sonar. Although the fish species Astyanax fasciatus is blind, they sense their environment and the movement of water around them with gel-covered hairs that extend from their bodies. Their ability to detect underwater objects and navigate through their lightless environment inspired a group of researchers to mimic the hairs of these blind cavefish in the lab. While the fish use these hairs to detect obstacles, avoid predators and localize prey, researchers believe the engineered sensors they're developing could have a variety of underwater applications, such as port security, surveillance, early tsunami detection, autonomous oilrig inspection, autonomous underwater vehicle navigation, and marine research. "These hair cells are like well-engineered mechanical sensors, similar to those that we use for balance and hearing in the human ear, where the deflection of the jelly-encapsulated hair cell measures important flow information," says Vladimir Tsukruk, a professor at Georgia Tech. "The hairs are better than active sonar, which requires a lot of space, sends out strong acoustic signals that can have a detrimental effect on the environment, and is inappropriate for stealth applications." Tsukruk and graduate students Michael McConney and Kyle Anderson conducted preliminary experiments with a simple artificial hair cell microsensor made of SU-8, a common epoxy-based polymer capable of solidifying, and built with conventional CMOS microfabrication technology. They found that the cell by itself could not achieve the high sensitivity or long-range detection of hydrodynamic disturbances created by moving or stationary bodies in a flow field. The hair cell needed the gel-like capsule-called the cupula-to overcome these challenges. "After covering the hair cell with synthetic cupula, our bio-inspired microsensor had the ability to detect flow better than the blind fish. The fish can detect flow slower than 100 micrometers per second, but our system demonstrated flow detection of several micrometers per second," says Tsukruk. "Adding the cupula allowed us to detect a much smaller amount of flow and expand the dynamic range because it suppressed the background noise." Source: Georgia Tech
