Researchers have long been trying to make electronics that are safe to eat. These include edible transistors, sensors, batteries, electrodes, and capacitors, which (if you put them together) are most of an edible robot. What’s been missing so far has been the thing that makes a robot distinct from a computing system, and that’s an edible actuator that would allow an ingestible robot to actually do something useful once you’ve swallowed it.
At IROS last week, researchers from EPFL’s Laboratory of Intelligent Systems, headed by Dario Floreano, presented a prototype of a completely edible soft pneumatic actuator made of gelatin. It probably doesn’t taste very good, but it’s biodegradable, biocompatible, and environmentally sustainable, and could enable all kinds of novel applications, as the researchers explain in their paper:
The components of such edible robots could be mixed with nutrient or pharmaceutical components for digestion and metabolization. Potential applications are disposable robots for exploration, digestible robots for medical purposes in humans and animals, and food transportation where the robot does not require additional payload because the robot is the food.
The robot is the food. Whoa.
The actuator is made from a mix of gelatin, glycerin, and water that’s poured into a mold. The overall design is a standard one for pneumatic actuators (and the performance is similar); the structure causes it to bend when inflated and straighten out again when pressure is reduced. What’s novel about this is the composition and edibleness, and as it turns out, making it edible has some additional benefits: Since gelatin is melty, the edible version could be capable of self-healing, which conventional pneumatic actuators typically are not.
The researchers conducted a gripper grasping test, adjusting the actuated force to allow the gripper to handle objects of different sizes and shapes, including: an apple (95.6 grams), a boiled egg (47.7 g), an orange (104.8 g), a Lego brick (25.7 g), and a bottle of chewing gum (153.1 g).Image: EPFL
At the end of the IROS presentation, an audience member asked the obvious question: The actuator is technically edible, but has anyone actually eaten one? In fact, they have, or at least bits and pieces left over from the manufacturing process. And as far as we know, none of the ingested actuators have later clawed their way out of anyone’s stomach from the inside.
As for what we have to look forward to with edible robots, I won’t even speculate, because you wouldn’t believe me. Instead, I’ll just quote the paper, so that you can not believe that instead:
Fully edible robots would help to study how wild animals collectively behave. The robots could also take a role of animals prey to observe their hunting behaviors, or to train protected animals to do predation. Once medical components are mixed into the edible composition, the robots could help preservation of wild animals or heal inside of the human body. When edible robots can be metabolized, they also function as energy storage providing an advantage in terms of increased payload with respect to non-edible robots that must be loaded with a food payload. This would be effective in rescue scenarios where the metabolizable robots can reach survivors in isolated places like inside a crevice or up on mountain. Last, but not least, since edible materials can generate electric energy, one could envisage autophagy (self-eating) function, like that of octopus, to extend their lifetime.