New York, Feb 19 (IANS) A team of scientists has developed small, soft biological robots -- bio-bots -- that can walk and swim on their own or when triggered by electrical or light signals.

These tiny muscle-powered robots were first 3-D printed and then seeded with muscle cells. The cells self-organised to form functional tissues that made the bio-bots move.

"These machines are now viewed as partially living, with the ability to form, the ability to age and the ability to heal if there's an injury," Taher Saif, a professor at the University of Illinois at Urbana-Champaign, said in a statement.

"Now that we have got them working, we are beginning to look back and try to understand how the cells organise themselves and what language they use to communicate. This is the developmental biology of living machines," Saif added.

The group developed multiple designs to make bio-bots walk in certain directions and to control their motion with light or electrical currents.

"As engineers, we usually build with materials like wood, steel or silicon. Our focus here is to forward-engineer biological or cell-based systems," added Rashid Bashir, head of the bioengineering department at the University of Illinois.

"The design is inspired by the muscle-tendon-bone complex found in nature. There's a skeleton or backbone, but made out of soft polymers similar to the ones used in contact lenses, so it can bend instead of needing joints like the body does," Bashir noted.

Saif said that the objective was not to make a walker and a swimmer, but to lay the scientific foundation so they have principles for building biological machines in the future.