// EPFL
A team of researchers from EPFL, Switzerland, presented what will be, as far as we know, the first fully ingestible robot capable of controlled movements. It has a slightly sweet flavor, a texture similar to gum, and the pneumatic battery is crunchy on the outside and acidic on the inside — like a lemon.
When a new robot is introduced, there are many pertinent questions to ask, but “can I eat it?” is usually not one of them.
“Normally” because, in fact, edible robots — and not just in the sense of being technically swallowable, with the respective benefits and risks, but truly ingestible: we can take a bite of them, chew them and swallow them… without having indigestion.
Until now, however, these ingestible robots have always come with a huge drawback: the engine and battery, both toxic and, most likely, of dubious flavor, enhances the .
The obstacle has been that ingestible soft components work under gas pressure, which requires pumps and valves difficult to manufacture without plastics and metals.
But in a new study, a team of researchers from the Laboratory of Intelligent Systems at EPFL in Switzerland, led by Dario Floreanopresented edible versions of both the batteries and the remaining components, resulting in what will be, as far as we know, the first fully ingestible robot capable of controlled movements.
Let’s start with this little creature’s battery. Generally speaking, a battery is just a energy storage and release system. In the case of this robot, the battery is made of gelatin and wax.
Chemical energy is stored in chambers with liquid citric acid and baking soda — both safe for consumption.
Citric acid is kept separated from bicarbonate by a membrane; When enough pressure is applied to the acid chamber, the membrane ruptures and the acid begins to slowly drip into the bicarbonate, which activates the battery and generates carbon dioxide gas, as well as sodium citrate (present in countless foods, from cheese to sour treats) as a byproduct.
Carbon dioxide travels through gelatin tubes to the actuatora type of component that converts a power source input, such as electrical, pneumatic, or hydraulic, into a mechanical movement to operate or control a system.
The actuator developed by the EPFL team is based on a relatively common design in soft robotics: interconnected chambers which, when pressurized, bend a slightly more rigid base.
Pressurization only produces a movement, but to produce a kind of “shaking” — an absolutely essential quality in any robot — the gas has to be released cyclically. This is where another great innovation achieved by the team of researchers comes in: an edible valve.
The valve works on the principle of snap-bucklingwhich consists of maintaining a stable (closed) shape until the pressure is sufficient to make it “pop” quickly to the open position, then returning to the initial state when the pressure drops.
The current version of the robot can achieve approximately four push-up cycles per minutefor a few minutes, until the battery runs out.
“One possible use case of our system is to provide nutrition or medication to hard-to-reach animals, such as wild boars,” explains the study’s lead author, Bokeon Quack. “Wild boars are attracted to live, moving prey, and in our case it is the edible actuator that mimics this behavior.”
The idea is that the robot can transport, for example, a vaccine against swine flu. Being cheap to produce, safe to use, fully biodegradable and capable of moving, it can be an effective strategy for targeted distribution, on a large scale, to animals that humans prefer to stay away from.
And, of course, it’s not limited to wild boars — by adjusting the size, the type of movement, the stimuli that activate it, and even the smell and taste, it would be possible to attract practically any animal that finds busy things appealing. Including humans.
Kwak says that, if someone ate this robotthe actuator and valve would have a slightly sweetdue to glycerol, and a texture similar to gums. The pneumatic battery is crispy on the outside and sour on the inside (like a lemon), thanks to citric acid.
Edibility, however, is not the priority of the projecthighlights Dario Floreano. “From a broader environmental and sustainable robotics perspective, our pneumatic battery and valve system are essential technologies because they are compatible with biodegradable pneumatic robots of various types.”
And even for those who are not particularly concerned about the environmental component (although they should be), in a scenario of swarms of robots in natural environments, simplicity and low cost are crucial factors to be able to scale in a useful way.
The results of the study were presented in a recently published in the journal Advanced Science.
