Crawling soft robot powered by temperature change

Detailed in Science Robotics, the inchworm-inspired robot could have applications in healthcare such as crawling through human bodies to deliver medicine, the team believes.

“It seems very simplistic but this is an object moving without batteries, without wiring, without an external power supply of any kind – just on the swelling and shrinking of gel,” said senior author David Gracias, a professor of chemical and biomolecular engineering at Johns Hopkins University.

“Our study shows how the manipulation of shape, dimensions and patterning of gels can tune morphology to embody a kind of intelligence for locomotion.”

Robots are made almost exclusively of hard materials like metals and plastics, an obstacle in the push to create robots ideal for human biomedical advancements.

Water-based gels are one of the most promising materials in the field of soft robotics, the team said. Researchers have previously demonstrated that gels that swell or shrink in response to temperature can be used to create smart structures.

Here, the Johns Hopkins team demonstrated how swelling and shrinking of gels can be strategically manipulated to move robots forward and backward on flat surfaces, or to have them ‘crawl’ in certain directions with an undulating, wave-like motion.

According to the team, their gelbots – which were created by 3D printing for this work – would be easy to mass produce. Gracias foresees a range of practical future applications in other areas as well as healthcare, including marine robots for patrolling and monitoring the ocean’s surface.

Gracias hopes to train the gelbots to crawl in response to variations in human biomarkers and biochemicals. He also plans to test other worm and marine organism-inspired shapes and forms and would like to incorporate cameras and sensors on their bodies.