New twisting artificial muscles propel nano-robots one step closer to medical applications

twisting artificial muscle 1

The possibility of a doctor using tiny robots in your body to diagnose and treat medical conditions is one step closer to becoming reality today, with the development of artificial muscles small and strong enough to push the tiny Nanobots along.

Although Nanorobots (Nanobots) have received much attention for the potential medical use in the body, such as cancer fighting, drug delivery and parasite removal, one major hurdle in their development has been the issue of how to propel them along in the bloodstream.

An international collaborative team led by Dr Javad Foroughi and Prof Geoff Spinks at UOW’s Intelligent Polymer Research Institute, part of the ARC Centre of Excellence for Electromaterials Science (ACES), have developed a new twisting artificial muscle that could be used for propelling nanobots.   The muscles use very tough and highly flexible yarns of carbon nanotubes (nanoscale cylinders of carbon), which are twist-spun into the required form.  When voltage is applied, the yarns rotate up to 600 revolutions per minute, then rotate in reverse when the voltage is changed.

Due to their complexity, conventional motors are very difficult to miniaturise, making them unsuitable for use in nanorobotics.  The twisting artificial muscles, on the other hand, are simple and inexpensive to construct either in very long, or in millimetre lengths.

“This new, giant, rotating type of actuation will open up lots of new opportunities for micro-machines,” said Prof Geoff Spinks, ACES Chief Investigator.

Similar twisting muscles are found in nature, such as octopus limbs and elephant trunks.   In these appendages, helically wound muscle fibres rotate by contracting against an incompressible, bone-less core.  The rotation in the helically wound carbon nanotubes used for the twisting artificial muscles is caused by an increase of liquid electrolyte volume within the yarn.

The new twisting artificial muscles research is published today in Science.  


In the animated video below, you first see a few bacteria like creatures swimming about. Their rotating flagella are highlighted with some detail of the flagella motor turning the “hook” and “filament” parts of the tail. We next see a similar type of rotating tail produced by a length of carbon nanotube thread that is inside a futuristic microbot. The yarn is immersed in a liquid electrolyte along with another electrode wire. Batteries and an electrical circuit are also inside the bot. When a voltage is applied the yarn partially untwists and turns the filament. Slow discharging of the yarn causes it to re-twist. In this way, we can imagine the micro-bot is propelled along in a series of short spurts.

Further information: Natalie Foxon 02 4221 3239

Last reviewed: 19 October, 2011