A school of small robotic fish, which are equipped with sensors to monitor oil spills or other environmental contaminants has been developed by MIT (Massachusetts Institute of Technology) scientists in the US.
According to a report in Discovery News, the robofish, made with only handful of parts and a blend of polymers, can wiggle their way through water like trout and tuna.
"The interesting aspect of this research is that we are the first group to tailor different polymers in different parts of the body with different dampening and stiffness properties," said Kamal Youcef-Toumi, a scientist at MIT who, along with Pablo Vildivia Y Alvarado, is developing the robofish.
"We are also looking at using the natural motion and behavior of the fish and replicating those motions," said Youcef-Toumi.
The 18 new robofish have advanced significantly since the original Robotuna was created at MIT in 1994.
Robotuna had more than 2,000 parts, including six motors, encased in its four-foot body.
These new models have less than 10 parts, including one motor, and are between five and eight inches long.
Youcef-Youmi and Vildivia Y Alvarado began developing the five-inch robofish four years ago, modeling their movements on freshwater fish like trout and bass.
These small fish swim mostly by moving the tail, while the rest of the body remains motionless.
Whatever the length or swimming method, all the robofish are encased in a special blend of molded polymers.
The body of the fish is one single piece of material, but each section of the body has a different stiffness, allowing the motion of one actuator to move through the robofish's entire body, propelling it forward.
One actuator allows for limited movement, basically forward and side-to-side. To move up and down and more complex movements will require two additional actuators be installed.
The unibody construction also protects the electrical and mechanical parts inside the robot; some robofish have been swimming for more than four years.
The robofish might mimic real fish, but they can't compete in terms of speed. The maximum speed of the robofish is less than one body length per second.
Some fish can swim up to 10 body lengths per second.
Movement requires energy, and the robofish currently get their power from an attached power cable.
Batteries could be installed to power robofish remotely in streams and bays, where they could be equipped with sensors to detect pollution or cameras to study animals that would be disturbed by the noise caused by propellers.