Top view of a biobot, consisting of a muscle cell-laden hydrogel and a spring-like skeleton. (Credit: IBEC)

Using 3D bioprinting, researchers have created biobots at the centimeter size range that can swim and coast like fish with unprecedented velocity. Rather than working with stiff or tethered scaffolds to prepare artificial robots, the researchers used biological robots based on a flexible serpentine spring made of a polymer that was 3D-printed.

Training and development of the tissue through mechanical self-stimulation upon spontaneous contractions creates a feedback loop due to the restoring force of the spring. This self-training event leads to enhanced actuation and larger contraction force. Such serpentine springs have not been included before in a soft robotic living system.

The work has applications in drug delivery and development of bionic prosthetics.