Nav: Home

New adhesive device could let humans walk on walls

February 01, 2010

Could humans one day walk on walls, like Spider-Man? A palm-sized device invented at Cornell that uses water surface tension as an adhesive bond just might make it possible.

The rapid adhesion mechanism could lead to such applications as shoes or gloves that stick and unstick to walls, or Post-it-like notes that can bear loads, according to Paul Steen, professor of chemical and biomolecular engineering, who invented the device with Michael Vogel, a former postdoctoral associate.

The device is the result of inspiration drawn from a beetle native to Florida, which can adhere to a leaf with a force 100 times its own weight, yet also instantly unstick itself. Research behind the device is published online Feb. 1 in Proceedings of the National Academy of Sciences.

The device consists of a flat plate patterned with holes, each on the order of microns (one-millionth of a meter). A bottom plate holds a liquid reservoir, and in the middle is another porous layer. An electric field applied by a common 9-volt battery pumps water through the device and causes droplets to squeeze through the top layer. The surface tension of the exposed droplets makes the device grip another surface - much the way two wet glass slides stick together.

"In our everyday experience, these forces are relatively weak," Steen said. "But if you make a lot of them and can control them, like the beetle does, you can get strong adhesion forces."

For example, one of the researchers' prototypes was made with about 1,000 300-micron-sized holes, and it can hold about 30 grams - more than 70 paper clips. They found that as they scaled down the holes and packed more of them onto the device, the adhesion got stronger. They estimate, then, that a one-square-inch device with millions of 1-micron-sized holes could hold more than 15 pounds.

To turn the adhesion off, the electric field is simply reversed, and the water is pulled back through the pores, breaking the tiny "bridges" created between the device and the other surface by the individual droplets.

The research builds on previously published work that demonstrated the efficacy of what's called electro-osmotic pumping between surface tension-held interfaces, first by using just two larger water droplets.

One of the biggest challenges in making these devices work, Steen said, was keeping the droplets from coalescing, as water droplets tend to do when they get close together. To solve this, they designed their pump to resist water flow while it's turned off.

Steen envisions future prototypes on a grander scale, once the pump mechanism is perfected, and the adhesive bond can be made even stronger. He also imagines covering the droplets with thin membranes - thin enough to be controlled by the pump but thick enough to eliminate wetting. The encapsulated liquid could exert simultaneous forces, like tiny punches.

"You can think about making a credit card-sized device that you can put in a rock fissure or a door, and break it open with very little voltage," Steen said. "It's a fun thing to think about."
-end-
The research was funded primarily by the Defense Advanced Research Projects Agency and also by the National Science Foundation.

Cornell University

Related Surface Tension Articles:

A novel salvinia-like slippery surface
Inspired by the hydrophobic leaves of Salvinia molesta and the slippery Nepenthes pitcher plants, a Salvinia-like slippery surface (SSS) consisting of protrusions with slippery heads was designed.
Surface tension, not gravity, drives viscous bubble collapse
By demonstrating that surface tension -- not gravity -- drives the collapse of surface bubbles in viscous liquids, a new study flips the previous understanding of how viscous bubbles pop on its head.
Illuminating cell surface receptors
Human cells sense and communicate via cell surface receptors on their surface.
Tadpoles break the tension with bubble-sucking
When it comes to the smallest of creatures, the hydrogen bonds that hold water molecules together to form 'surface tension' lend enough strength to support their mass: think of insects that skip across the surface of water.
Finding connections at the surface
How and where receptors touch at the surface of a cell may influence the strength of neuronal connections and contribute to identifying better medical interventions for pain, cancer other diseases.
Scratching the surface of perovskites
Professor Yabing Qi and his team in the Energy Materials and Surface Sciences Unit at OIST, in collaboration with researchers at the University of Pittsburgh, USA, have, for the first time, characterized the structural defects that prompt the movement of ions, destabilizing the perovskite materials.
What makes the Earth's surface move?
Do tectonic plates move because of motion in the Earth's mantle, or is the mantle driven by the plates' movement?
Tension around autonomy increases family conflict at end of life
Conflict within families can be stressful and confusing, and it can lead to feelings of sadness.
How newly found tension sensor plays integral role in aligned chromosome partitioning
A Waseda University-led research found that oncogene SET/TAF1, which was found to be a proto-oncogene of acute myeloid leukemia (AML), contributes to proper chromosome partitioning as a tension sensor.
Our social judgments reveal a tension between morals and statistics
People make statistically-informed judgments about who is more likely to hold particular professions even though they criticize others for the same behavior, according to findings published in Psychological Science, a journal of the Association for Psychological Science.
More Surface Tension News and Surface Tension Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.