Inspiration for new propulsion system for boats -beetle larvae

The newest propulsion system for small robotic craft would not need  paddles, sails, or motors and would harnesses the energy

within the water’s surface. This method of propulsion for small water craft and robots was inspired Sung Kwon Cho, senior researcher and a professor of mechanical engineering and materials science in Pitt’s Swanson School of Engineering by reading a paper about how beetle larvae move through the water. If developed this system could be an efficient and low-maintenance system for small robots and boats that monitor water quality in oceans, reservoirs, and other bodies of water.

Cho and his team-Pitt engineering doctoral students Sang Kug Chung and Kyungjoo Ryu-substituted the larva’s back bending with an electric pulse. In their experiments, an electrode attached to a 2-centimeter-long “mini-boat” emitted a surge that changed the rear surface tension direction and propelled the boat at roughly 4 millimeters per second.

A second electrode attached to the boat’s front side served as the rudder.

The lovely floating beetle larvae how do they do it?

The beetles technique destabilizes the surface tension of the water and this allows the water to move the beetle forward. The larva resting in the water causes the surface tension to pull beetle-waterlily-leaf-larva-prepares-propel200-bgequally on both sides. To move forward, the larva bends its back downward to change the tension direction behind it. The forward tension then pulls the larva through the water.The new propulsion system surrounds the object with an electric pulse breaks the surface tension of the water and causes the craft to move via the surface’s natural pull.

Today these small research and robotic devices are typically propeller-driven. The Pitt system has no moving parts and the low-energy electrode that emits the pulse could be powered by batteries, radio waves, or solar power.

The researchers will present their findings Jan. 26 at the Institute of Electrical and Electronics Engineers’ 2009 Micro Electro Mechanical Systems (MEMS) conference in Sorrento, Italy.


Excerpts courtesy of Energy Daily

Baby Beetles Inspires Mini Boat Powered By Surface Tension Staff,  Energy Daily January 23, 2009.

Image courtesy of  University of Pittsburgh

Video of rudder rotation courtesy of


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