Researchers have engineered biocompatible, flexible microrobots that modify their Robots can change shape depending on their surroundings. Source: EPFL/ETHZshape. This morphing enables the bots to travel through narrow blood vessels or under conditions of changing viscosity without undermining speed or maneuverability.

Deformation can be preprogramed in the hydrogel nanocomposites, which contain magnetic nanoparticles to enable control via an electromagnetic field. These deformations allow the devices to automatically assume the most efficient shape when navigating a particular obstacle. The robots can also navigate on their own through cavities by utilizing fluid flow.

A tube-shape with a flat tail to paddle was deemed optimal for swimming through a liquid with low viscosity, while a helix shape proved more efficient at getting through more viscous fluids. The autonomous shape change is triggered by changes in sucrose concentration.

Scientists from ETH Zurich (ETHZ), Ecole Polytechnique Fédérale de Lausanne (Switzerland) and University of Cambridge (U.K.) contributed to this research, which is published in Science Advances.

Microbot systems have been under development as medical devices that can move through bodily fluids and deliver targeted therapies in the human body. For example, biohybrid magnetic robots based on microalgae subjected to a magnetite dip-coating were devised for minimally invasive applications by an international research team.