A tiny sliver of elastic material swims along inside a narrow tube, coiling up and changing shape in response to the thickness of fluid and the contours of the tube around it as it moves towards its goal.
The miniature robot - the bacteria-inspired brainchild of a team of scientists in Switzerland seeking new methods to deliver drugs to diseased tissue - is designed to wend its way through blood vessels and other systems in the body.
The team is led by Selman Sakar at the Ecole Polytechnique Federale de Lausanne (EPFL) and Bradley Nelson at ETH Zurich, two leading science and technology research institutes.
"Nature has evolved a multitude of micro-organisms that change shape as their environmental conditions change. This basic principle inspired our microrobot design," Nelson said.
"The key challenge for us was to develop the physics that describe the types of changes we were interested in, and then to integrate this with new fabrication technologies."
The tiny soft microswimmer robot they have developed is a few millimetres in length and made using a folding technique similar to the Japanese art of origami, helping it adapt to the environment around it, Sakar said.
The robots are made from hydrogel nanocomposites that contain magnetic particles, meaning their movement can be guided with a magnetic controller.
The team is now working on improving the microbot’s ability to swim through fluids such as those found in the human body.
Other researchers working on the use of microbots for use in the human body include a team at the City University of Hong Kong who has developed a soft robot that moves like a caterpillar, also designed to deliver drugs within the body.
Their flexible robot has hundreds of 1mm-long hair-like pointed legs. In 2018, the team constructed the robot from a type of silicon embedded with magnetic particles. The rubbery material is flexible and can be cut to form different shapes and sizes.