Chameleon's elastic tongue inspires fast-acting robots

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Engineers from Purdue University in the US have taken inspiration from the incredible fly-catching ability of chameleons and salamanders to develop a new class of high-speed soft robots and actuators.

Chameleons, salamanders and many toads use stored elastic energy to launch their sticky tongues at unsuspecting insects located up to one-and-a-half body lengths away, catching them within a tenth of a second.

Led by Ramses Martinez, an assistant professor in Purdue’s School of Industrial Engineering,  the team has developed a new class of soft robots and actuators capable of re-creating these high-powered and high-speed motions using stored elastic energy.

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The robots are fabricated using stretchable polymers similar to rubber bands, with internal pneumatic channels that expand upon pressurisation. The elastic energy of these robots is stored by stretching their body in one or multiple directions during the fabrication process.

Similar to the chameleon's tongue strike, a pre-stressed pneumatic soft robot is capable of expanding five times its own length, catch a live fly beetle and retrieve it in just 120 milliseconds.

Image created by Ramses V. Martinez, an assistant professor at Purdue University, and his students.

“We believed that if we could fabricate robots capable of performing such large-amplitude motions at high speed like chameleons, then many automated tasks could be completed more accurately and in a much faster way,” Martinez said.

This technology is described in the October 25 edition of Advanced Functional Materials.

As well as the robot tongue the team has also developed robotic grippers - able to hold up to 100 times their own weight - inspired by the by the stressed tendons that enables many types of bird to perch whilst asleep.

Martinez said these pre-stressed soft robots have several significant advantages over existing soft robotic systems. First, they excel at gripping, holding and manipulating a large variety of objects at high speed. They can use the elastic energy stored in their pre-stressed elastomeric layer to hold objects up to 100 times their weight without consuming any external power.

"We envision that the design and fabrication strategies proposed here will pave the way toward a new generation of entirely soft robots capable of harnessing elastic energy to achieve speeds and motions currently inaccessible for existing robots," Martinez said.