New suction-cup system spins water to stick to rough surfaces

anon463637 | 167 points

My understanding of it after a quick read of the paper: you want to make a suction cup. The usual way is with a solid cup (think plastic) with a softer rubber-like ring around it. Near the ring, you will have atmospheric pressure (high) outside, and vacuum pressure (low) inside, so if the ring doesn't make perfect contact with the surface, some air is going to come in and ruin you vacuum. What they are doing is that they are rotating a bit of water in the suction cup, which because of centrifugal force will come close to the suction cup frontier in a ring-like shape. This water ring will -- thanks to fluid mechanics black magic -- have a different pressure at its exterior and its interior. Its interior pressure will necessarily be the same as the vacuum, and you can make it so that the pressure outside is the same as the atmospheric pressure, hence, according to this paper, if the rubber ring fails to make hermetic contact, air won't come in because at the frontier of the cup, the pressure is the same both outside (atmosphere) and inside (exterior of the water ring).

NougatRillettes | 4 years ago

Pretty cool. Reminded me of what this guy is doing, he calls it "orthosonic lift": https://youtu.be/kG6vXGidQbo

Some more info: http://sciencechatforum.com/viewtopic.php?nomobile=1&f=77&t=...

I believe he has a couple of patents on the technology, but not sure he'll ever get around to making something practical with it.

ta1234567890 | 4 years ago

Kind of similar to the reason you'd wet a suction cup before using it: the water helps plug any small air gaps. But in this version, a fan spins the water and air inside the cup, with the heavier water being forced to the edge, and any water leakage being replaced from a reservoir.

flashman | 4 years ago

Is this the same mechanism as the immersion blender trick? (https://youtu.be/TrZyuCh9df0?t=424)

catalogia | 4 years ago

What about ferromagnetic fluid? You can still spin it if you are aiming to push it 'centrifugally' into the features of the vacuum boundary, but you shouldn't lose a lot during the detachment.

(Plus it looks much more sci-fi.)

AliAdams | 4 years ago

No idea if this is actually a new idea but it's definitely new to me and I love seeing it. What a cool concept, likely to be a few applications in industry beyond spiderbots.

jcims | 4 years ago

> The resulting inertial force generates a steep pressure gradient, allowing a high vacuum to be maintained at the center of the cup's vacuum zone

Sounds like a "momentum transfer" vacuum pump, shaped so that the output side bleeds out along the rim.

https://en.wikipedia.org/wiki/Vacuum_pump#Momentum_transfer_...

Terr_ | 4 years ago

I can't say I am super looking forward to hexapod wall climbing robots.

jakedata | 4 years ago

China is where all the cool stuff is happening. Whereas americunts are busy worrying about which toilet should be used by whom and whether illegal aliens deserve free health care or not and how to kill some guy half way around the world because he said bad things

rusttoxic | 4 years ago