It is inspired by origami
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A Transformer-style robot that travels through the human body to cure diseases has been created by scientists. The tiny shape-shifting machine is inspired by the Japanese paper-folding art of origami.
It is controlled by magnets - carrying payloads directly to a tumour, blood clot or infection. The 'millibot' is set to revolutionise medicine - replacing pills or intravenous injections that can cause life-threatening side effects.
It can crawl, spin and swim to enter narrow spaces - dispensing drugs or investigating inner workings. The actuator provides untethered control for non-invasive operation - allowing for miniaturisation.
It resembles the plot of Fantastic Voyage in which a submarine and its crew were shrunk - and injected into a dying patient. They destroyed a blockage with laser guns - after venturing through veins into his brain. The sixties sci-fi classic starring Raquel Welch has stirred imaginations ever since.
The device also mirrors The Transformers - comic book characters that disguise themselves by turning into cars or trucks. Corresponding author Dr Ruike Zhao said the "spinning-enabled wireless amphibious origami millirobot" is as agile as its name implies.
It moves "elegantly and speedily" over an organ's slick, uneven surfaces and powers through body fluids - propelling itself wirelessly while transporting therapies. Unlike tablets swallowed or liquids injected, it withholds medicine until "it reaches the target and then releases a high-concentration drug".
Dr Zhao said the robot described in Nature Communications is "the most robust and multifunctional robot we have ever developed". The mechanical engineer added: "That is how our robot achieves targeted drug delivery."
The ground-breaking design goes beyond most origami-based robots which only use foldability to control how they morph and move. Dr Zhao, of Stanford University, California, likened certain actions to a minute accordion squeezing out medicine.
The device's dimensions also enable it to remain rigid on its way to missions. As a result, its unfolded form inherently lends itself to propulsion through the environment.
Such broad-minded considerations allowed the US team to get more out of the materials without adding bulk. The more functionality achieved from a single structure the less invasive the procedure is, she explained.
Another unique aspect are geometrical features - including a long hole in the centre and slits angled up the sides - to reduce water resistance and boost efficiency.
Dr Zhao said: "This design induces a negative pressure in the robot for fast swimming and meanwhile provides suction for cargo pickup and transportation. We take full advantage of the geometric features of this small robot and explore that single structure for different applications and for different functions."
The bot measures less than a third of an inch wide (7.8mm). It is fitted with magnetic plates - and can change direction in an instant.
Methods of locomotion are self-selected depending on the obstacles it has to overcome in the body - ranging from organs to torrents of fluid. Just by shifting the strength and orientation of the magnetic field, the bot can sail ten times its length - in a single leap.
By folding or unfolding, a pumping action is able to deliver liquid medicine. Twisting also produces a sucking mechanism for transportation of cargo.
Dr Zhao said: "We started looking at how all these work in parallel. This is a very unique point of this work, and it also has broad potential application in the biomedical field."
It is hoped her robots will eventually be carrying instruments or cameras into the body - as well as dispensing medicine. It would change how doctors examine patients. Her lab is also working on ultrasound imaging to track where robots go - eliminating any need to cut open organs.
Dr Zhao's 'first-of-its kind' bot is currently undergoing tests prior to animal experiments. If they are successful, human clinical trials will follow.
She also plans to continue scaling down her robots to further biomedical research at the microscale. Added Dr Zhao: "Millibots may serve as minimally invasive devices for biomedical diagnosis and treatments."