How a soft octopus robot grips what metal arms can't

HostI was watching this clip of a robot trying to pick up a single strawberry the other day. It was painful to watch. The metal claw just kept overshooting, and when it finally got a grip, it just turned the berry into a pile of red mush. It feels like we're great at building robots that can weld a car door, but we're still failing at the basic stuff a toddler can do. How do we even begin to build a machine that can be gentle?

GuestWe have to stop thinking about bones. If you look at an octopus, it's basically a bag of water and muscle. It has no hard parts except for a tiny beak, yet it can unscrew a jar lid or catch a slippery fish without crushing it. In the lab, we call this soft robotics. Instead of using hard metal joints and stiff motors, we make arms out of stretchy rubber and silicone. It's a total shift in how we think about power. Usually, a metal arm has to be told exactly where to go, down to the hair. But a soft arm? It just bumps into things and wraps around them. It has what we call give. The softness is actually the secret to its strength because it doesn't have to be perfect to work.

HostBut if it's all just rubber and jelly, how does it actually hold on? If I'm trying to lift something with a heavy weight, a wet noodle of an arm doesn't seem like it would help much.

GuestThat's where the air comes in. These soft arms aren't just solid rubber. They have hollow chambers inside, kind of like a series of tiny balloons. When you pump air into those chambers, the arm curls. By changing how those balloons are shaped, you can make the arm twist, bend, or lengthen. It's called a pneunet. When you want to grab something, you pump in the air, and the arm wraps around the object. The air gives it enough pressure to hold on tight, but because the skin of the arm is soft, it spreads that pressure out. A metal claw puts all its force on two tiny points, which is why the strawberry breaks. The soft arm hugs the whole fruit at once.

HostThat sounds like a math problem that would break a computer. Trying to track where a floppy piece of rubber is in space? I would think you would need a million sensors just to know if the arm is straight or curled.

GuestYou would think so, but it's actually the opposite. This is the part that really trips people up. With a metal robot, the computer has to do all the work. It has to calculate every angle and every joint. With a soft robot, the material does the thinking for you. We call it body smarts. When a soft arm hits a table, it just deforms. It moves out of the way because it's squishy. It doesn't need a sensor to tell it there's a table there; the physics of the rubber handles the collision. The arm shapes itself to whatever it touches. This means the computer code can be much simpler because the arm is naturally safe and flexible. It's a bit like how you don't have to think about the shape of your hand when you grab a bag of chips. Your fingers just mold to the bag.

HostOkay, but an octopus has those hundreds of little suckers too. Is that just for show, or do they actually do something that a normal gripper cannot?

GuestThe suckers are the real game changer for handling weird textures. On a robot, we can make these out of soft silicone. When the arm wraps around a wet rock or a piece of coral, those tiny cups create a seal. But there's a twist. Some of these new robots use something called active suction. We can use a tiny vacuum line to pull the air out of each cup individually. This lets the robot pick up things that are totally flat, like a pane of glass, or things that are very rough, like a brick. A metal gripper would just slide right off a wet, slimy rock. But the soft cups can reach into the tiny cracks and holes on the surface and lock on. It's a mix of friction and suction that gives it a massive amount of grip without needing a lot of brute force.

HostIt still feels a bit like a toy, though. Can something this squishy really do a real job?

GuestThink about a surgeon. If you're trying to move a delicate organ out of the way during a light-based surgery, you don't want a cold metal rod poking around in there. You want a soft, flexible tool that can snake through the body and gently nudge things aside without causing a tear. Or think about the bottom of the ocean. Most of the creatures down there are made of jelly. If you send a big, heavy metal sub down there with a giant claw, you're going to destroy the very things you're trying to study. Soft robots can reach out and grab a jellyfish without leaving a mark. We're even looking at using them in space to catch old satellites that might be spinning or breaking apart. A hard robot would just smash the satellite into more pieces, but a soft one can absorb the hit.

HostSo the real goal isn't making a stronger hand, but making one that knows how to fail and bend.

GuestWe're finding that the most useful robots might be the ones that are the least like machines and more like the things we find in a tide pool.

HostThat strawberry from the start might finally be safe if the hand picking it's just as soft as the fruit itself.