I know that many sentient robots in sci fi stuff eat food even if it is just for pleasure, energy or make them appear more like real humans and animals.

Well I was thinking how would such digestive system could work. I believe that in a far future robotics could be advanced enough to emulate a digestive system using 100% inorganic materials and maybe nanobots or a kind of artifitial endocryne system could emulate the enzymes that break down food. the trick is make the android produce chemicals continuously like humans do like salive and the stomach acid.

what kinds of technologies could make it possible?

If androids eat food along with having taste sense they could eat how much they wanted without worrying about health problems assossiated with overeating. this could make them superior to humans in more ways.


2 Answers 2



Biology is pretty good at getting the full efficiency you need. Energy can be extracted from food and stored. With technology we can emulate such things and sometimes improve on it. Enzymes are very efficient and we make many artificial ones already.

A robot can leverage this. Humans need a wide range of energy during their lives. A robot most likely needs only needs one kind for it's power. Most likely electricity will be used for both locomotion and thinking. Food can then be processed focusing only on the nutrients that can be used for power generation.

Besides making enzymes an efficient method is required to reduce the food to manageable bits. Both chewing, acids and slow movements of the stomach, in combination with enzymes, can break it down. Each of these can be generated and simulated.

All this is already possible. There exist full simulations to create such things. What is still missing is making it exact to reduce it to the right medium that can then be stored, as well as used as fuel at a later time.

Teeth/grinder, artificial stomach with acid and some enzymes for reducing it to mush. Then more enzymes to store it. Then more to make it usable/burn it for the energy.


We need to start with one truth: Both humans and robots can eat less-than-useful things

My suggestion will make more sense if you remember that humans can eat negative-calorie foods.

Food provides your body with a variety of nutrients, including three main categories that dole out energy in the form of calories: carbs, fats and proteins. Your body has to expend energy in order to digest and process any food you eat. The amount of energy required varies based on the food. The term negative-calorie food typically refers to a food which supposedly takes more calories to eat, digest and process than it naturally contains and gives to your body. (Source)

Now, that article goes on the explain that there may be no such thing as foods that take more calories to consume than they provide the body as energy. Let's ignore that for a moment. Distilled water has no calories. It takes more energy to drink it and process it away (aka, urine) than it will ever give to my body. This is an important point.

But that article makes another important point. It says, "Food provides your body with a variety of nutrients, including three main categories that dole out energy in the form of calories: carbs, fats and proteins." In other words, this whole issue is about more than just energy. It's about all the things your robots need to survive.

What might a robot need other than energy? Lubricants. And if they're self-replicating, a whole bunch of stuff.

But what the robot needs, we don't, and vice versa

Humans can eat sand. It doesn't do us any good (more negative calorie food!), but we can eat it. On the other hand, your robots might need the silica! So it makes sense that your robots would want to eat sand even while humans don't - but they both could. Just as they could both eat rutabaga, but your robots probably won't get much out of rutabaga.

But how would the digestion work?

The human digestion system, which works with a combination of enzymes, acids, and various squishy stuff that serves to transport and filter the goods, could be called nothing more than a material processing system. Once you realize that, you realize that a gasoline refinery is just another form of digestive system. Crude oil goes in, magic happens, a useful energy-providing substance comes out, and gets delivered by pipes, trucks, and pumps until used to make your car go. A macro digestive system compared to humanity's micro digestive system.

What you'll be doing is miniturizing what we today know as macro digestive systems. You're creating a chemical processing plant the size of the human gullet the relieves the incoming mass of any useful energy-providing or other substances to be moved along to where they're needed to keep the robot going.

The result is a robot that could enjoy a meal with a human! The robot may not actually get much out of the meal... but when it comes time for the robot to cook, the human won't get much out of that meal, so they're even. And since they can both eat things that don't provide a lot of value, they'll both need sewage collection, transport, and processing systems. Just to make a point. You're robots will need toilets.

I'll leave it as an exercise for the OP to figure out what elements the robots specifically need, look up how those elements are gathered and processed by humans, and then write the story to indicate that/those processes had been miniturized.


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