Paolo Rossi Castelli 2 June 2022 18 min read

Robotics and medicine: 'Millirobot' has been created to bring medicine to the intestine.

A new technique has been developed in the field of robotics and medicine by bioengineers at the City University of Hong Kong. A microscopic robot literally walks into the digestive tract, to release medication at points set by a doctor.

In the not too distant future, administering medicines - especially when it is very important that they reach specific destinations - could be very different from what we all know today.

Bioengineers at the City University of Hong Kong have created a tiny millirobot, smaller than a centimetre, a robot called Fibot. Thanks to the features of its nanofibres - fibres with a diameter of one ten-thousandth of a millimetre - and the special way in which they are assembled, it is able to administer medicines to very specific points on the digestive tract, without leaving visible traces of its passage.

Bioengineers presented Fibot in a study published in the scientific journal Matter (Cell group) and also in an explanatory YouTube video


The micro-robot looks like a sort of millipede, with a protective upper part in the form of a soft membrane, and a lower part with lots of needles that move like very thin legs, allowing safe movement in very difficult environments, like the rough walls of the stomach or those of the intestine, which are constantly contracting (peristalsis).

Fibot needles are designed to withstand the acidic pH of the stomach, and to attach themselves to the walls of the intestines without damaging them. They are able to respond to special external magnetic fields (now activated by researchers and, in the future by doctors) that control the millirobot’s direction and path.

How Fibot releases medicine
When it passes from the stomach to the intestine (from a very acidic to a gradually more neutral and then alkaline environment) it begins to disintegrate. The first structures to dissolve are the needles themselves, which take around 40 minutes.

As medicine is inserted into these millirobot components, the active ingredient is first released at the site where the millirobot anchors.

As the 'legs' disappear, the attachment to the intestinal wall dissolves, and Fibot resumes its journey, guided by the pull of the external magnetic field.

As it progresses, the upper membrane, which may contain another medicine to be released in a less specific manner, also gradually liquefies. In this way, a second active drug is administered. As the alkalinity increases, everything dissolves, in a process that takes up to seven hours. At the end, nothing identifiable remains, as all the materials used are biocompatible and biodegradable.

A milestone for robotics in medicine, with no risk of damage.
Tests carried out in pigs' stomachs, where the Fibot advances 7 centimetres every 10 seconds, and then in rabbit intestines, also confirmed that the millirobot does not cause any kind of inflammation and that because of its features, it does not penetrate the outer layers of the intestinal wall. Therefore it does not pose any risk of perforating the wall itself.

Many studies are still needed before the first tests on humans, but everything we have seen so far gives rise to hope that systems like this can help to make the administration of medicine more effective, precise and safe.


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Paolo Rossi Castelli

Journalist since 1983, Paolo has been dealing with scientific divulgation for years, especially in the fields of medicine and biology. He is the creator of Sportello Cancro, the site created by on oncology in collaboration with the Umberto Veronesi Foundation. He collaborated with the pages of the Science of Corriere della Sera for several years. He is the founder and director of PRC-Comunicare la scienza.