Paolo Rossi Castelli 23 March 2023 16 min read

A new snail-inspired robot

Researchers at Carnegie Mellon University (USA) have created a gel that can move and record electrical impulses. If cut or damaged, it can reconnect its two severed ends.

Soft robotics is one of the most advanced forms of robotics. As the name suggests, it is based on soft, self-repairing materials, which have qualities that are particularly suitable for measuring devices and also, in the future, prostheses.

Soft robotics has been the subject of studies for some years now, but so far the results - at least in the biomedical field - have almost always been unsatisfactory, mainly due to technical limitations. Now, however, bioengineers at Carnegie Mellon University in Pittsburgh (USA) appear to have solved most of the material problems and have created a very promising soft robot.

As described in the scientific journal Nature Electronics, the basic principle is to use a material in the form of a gel that conducts electricity like metals, into which chips and power sources like mini-batteries can be inserted. The gel also has to be able to repair itself if damaged or subjected to stress.

A liquid metal alloy 

The US researchers therefore developed an alcohol gel containing silver flakes and gallium particles: to all intents and purposes a kind of liquid metal alloy, with high conductivity, low rigidity, and a marked ability to resist mechanical stress. They then placed a mini-battery power supply and a bioelectrode to transmit impulses (this can measure the electrical activity of muscles anywhere in the body, depending on where it is placed) into the gel.

To explain what this is more clearly, the researchers also produced a video in which they filmed a snail-shaped soft robot. The video also shows the soft robot applied to a toy car and then to an arm and a leg. As we can see in the images, when the electrode is cut or subjected to a strong pull that causes it to break, its ability to generate electricity and therefore to make an object move (or to register an impulse) is severely affected (the speed at which the toy car or the snail moves is halved). However, in seconds the gel matrix manages to reconnect the two severed ends, and everything continues in almost the same way as before the cut, recovering approximately 70% of the energy transmitted before the injury.

In the case of the arm and leg, the soft robot can record electromyography anywhere in real time, without painful stimuli like those used in classic tests. It could also be a material to use in next-generation hybrid robotic prostheses.

Also useful for monitoring the environment

Another advantage is sustainability: the gel can be used over and over again, at least in theory, moving from one device to another, and could therefore also be useful for monitoring the environment, for example, in water.

In general, there are a wide range of applications for such a versatile material, because various types of devices linked directly to the human body could be made thanks to the soft robot. Laboratory testing, led by Carmel Maijdi, who has been working on these issues for years, is in full swing.


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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.