A team at Washington State University has developed the WaterStrider robot, a tiny aquatic robot inspired by water striders. Measuring just 22 mm in length and weighing 56 milligrams, the robot utilizes a groundbreaking “shape memory actuator” to propel itself across the water’s surface. This actuator, at 7 mm in length, is claimed to be the world’s smallest of its kind.
The WaterStrider’s actuator employs two minuscule wires made of a nickel-titanium alloy that contracts when heated and returns to its default state when cool. By applying a pulsating electrical current, the wires rapidly switch back and forth, causing the connected arms to flap. This mechanism enables the WaterStrider to paddle across the water at a speed of approximately 6 mm per second, with its arms flapping up to 40 times per second.
The robot’s carbon fiber body features four disc-like feet that maintain surface tension, preventing it from sinking. The researchers, led by Assoc. Prof. Néstor O. Pérez-Arancibia and engineering PhD student Conor Trygstad also created a smaller robot called the MiniBug for comparison.
The WaterStrider robot weighs 55 milligrams and can move at 6 millimeters per second (Image by Bob Hubner, WSU Photo Services).
Potential Applications
The team is currently working on integrating the power supply into the robot and aims to develop other insect-inspired robots capable of moving both on and beneath the water’s surface. Potential applications for these aquatic robots include artificial pollination, search and rescue operations, and environmental monitoring. Moreover, the shape memory actuator holds promise for applications in micro-fabrication and robotic-assisted surgery.
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