Cellulose films could provide flapping wings and cheap artificial muscles for robots.
Researchers at Inha University in South Korea have demonstrated that cellulose, the main ingredient in paper, can bend in response to electricity. The treated cellulose is lightweight, inexpensive, and has low power requirements, compared with similar electrically active materials.
This thin film of gold-coated cellulose flaps like dragonfly wings in response to an electrical current. The material, called electroactive paper, may serve as wings for small flying robots. (Courtesy of Zoubeida Ounaies, Texas A&M University.)
The Korean researchers are now working with NASA to develop insect-sized, wirelessly powered flying vehicles with flapping paper wings. Such vehicles could fly into areas unsafe for humans and test for hazardous gases -- or survey the surface of Mars from the air.
[Click here for images of this movable paper.]
The researchers, led by Jaehwan Kim, associate professor at the university, made the electrically active cellulose by dissolving paper pulp, forming it into sheets, and coating it with a layer of gold as an electrode. Some areas of the cellulose film are highly ordered, while in other areas, the cellulose strands are tangled like spaghetti. The movement of ions through the paper -- and the movement of cellulose strands themselves, which have negative and positively charged ends -- causes the paper to bend in response to an electrical current. The bending is driven by the ordered regions, but free space in disordered regions allows ions to flow more freely and adds to the paper's ability to deform.
Materials that move in response to electrical current are called piezoelectrics. Kim's cellulose is one of a new class of these materials, called electroactive polymers, that have generated excitement in the scientific community for their potential uses in many areas: artificial muscles, chemical sensors, visual displays, the moving parts of robots, and batteries.
"The value of electrically active paper is that it's lightweight and has a high deflection [movement] at low voltage" compared to traditional electroactive polymers, says Sang Choi, senior research scientist at the NASA Langley Research Center. When a small voltage is applied to Kim's paper, it can move a relatively large distance; for instance, in experiments, the tip of a 30-millimeter-long strip of electroactive paper was displaced 4.2 millimeters. Indeed, the strength of the electric field required to move the tip of the paper to its maximum displacement is one to two orders of magnitude less than is required by other electroactive polymers. And the paper can change shape quickly, moving back and forth as fast as once every 0.06 seconds.
NASA's Choi is interested in Kim's material because, compared with conventional piezoelectrics and other electroactive polymers, it is very lightweight and requires very little power. Together, Choi and Kim are designing a small flying vehicle with cellulose wings powered by ambient microwaves. Choi says NASA expects such robots to play an important role in its long-term exploratory missions. For example, small robots with moving parts made of paper or other materials might fly low over the Martian surface to monitor its topology. Still, it's not clear that cellulose can withstand the extreme conditions in outer space.
Researchers are testing whether robotic dragonflies could be agile and elusive fliers.
The latest product from Redmond: a Windows program for creating robot software.
Guest (tom)
i doubt it is going to be able to be made cheaply as it contains gold but maybe this is the technology every country needs to finnally start to use up there gold or we could just continue to sit on it foreva
Guest (Martin G. Smith)
Each day, when I walk into the shop I am met with what is new coming down the Highway of Light. So here it goes – We have all these developments, all this technology and the E-Commerce’rs of the world trying to make a fast buck out of it, hoping for it to be the next BIG THING.
Well how is this for a reality check, we are a 14000 Sq Ft facility rapidly filling up with latest of all that is best, sort the good tantalizing bit from the spew that too often represents itself as ‘New and Improved’. And when I read this latest from a field we are already making a foray into, solving another problem that we will no longer have to think about, I am grateful to all those folks who have done the work.
As far as being the next big thing, we don’t have to worry about it because we think we are the Only next thing that makes any sense and that we copied out of the MIT Fab Lab, Thanks Dr Gershenfeld
Guest (Ima Pseudonym)
WTF was THAT? Free association? English a second language for you, or are you just insane?
Guest (Martin G. Smith)
Look Further if you can identify yourself
Ask Nicely and I will give you enough inklings to get to a clue.
Guest (Arthur Collins)
What is your company's web page so we can talk about your's and some of my world changing products.
Guest (Martin G. Smith)
Guest (David Pearce)
Two points from this piece:
1. The material does not sound like a piezoelectric, which are all ferroelectric materials and do not respond to electric current (they are insulating dielectrics) but electric field. Maybe the writer has simply confused the terms.
2. Flying things such as insects do not have actively bending wings, but power rigid wings at the root. This bendable paper would not appear to offer anything in terms of making wings for flying. It could be useful for making active surfaces for wings, but that's another story.
Guest (Martin G Smith)
Might it be that the wings were simply intended as a Proof of Concept, showing the potential of the process rather than a practical application thereof.
Guest (Paul)
I was hoping I wasn't the only one wandering what he was talking about.
Guest (Arthur Collins)
Aluminum foil and a tinture of iodine also works. Why is this news? I developed a variety of "printable" electronic devices and simple circuits using conductive inks back in the mid-70s. Couldn't get anyone interested even though I was handing out business cards that were printed with these invisible circuits on a small offset press. These business cards functioned as short range FM recievers for a transmitter hidden in my briefcase. The cards used a piece of doped cellophane tape placed over a horseshoe shaped cut-out in the card which served as its speaker. At the time I was interested in licensing the technology to companies that might want to produce audio and visual effects on their packaging. Looks like I gave up on it too soon.
Guest (Arthur Collins)
It isn't a piezoelectic effect but rather an inductive force effect. the large Xanthane molecule reorients itself in the direction of electric current, much like the nodules within a Liquid Crystal Display. The only reason they used gold foil was due to the stiffness and material fatgue properties of other conducts. Superglue doped with a metal tincture also works. If you can find cellophane films anymore. You could probably build your own articulating devices. A cardboard spider was an interesting experiment. Just remember that these forces are weak, but only due to the fragle nature of the cellophane. Laminating it between layers of plastic wrap increased their force expotentially.
Really? I tried constructing actuators out of a strip of cellulose paper and electrodes out of conductive paint. It didn't work.
Guest (Keith)
why stop with adding stiffness
nanotubs could carry the electricity or even heat to or away from an area to cause expansion/contraction. that is an area that might be explored with other materials as well
Guest (r)
.06 recovery rate well suited to insect like wake captue flight... no?
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Guest (Brian Glassman)
There is more to this than robotics
Cellulose films and the new class of electro active polymers are going to be one of the key components to the impending micro robotic industry. However, technologists should not ignore the breath of current applications for this technology. For example, if active cellulose films can be produced cheaply, they can dramatically aid advertisements. Imaging being in a store and a sign in front of you catches your eye by interestingly contorts to highlight the items below on sale. A cheap means of adding even weak controllable motion has a much larger impact than just simple winged robotics. It will take a little time to do so, but if this can be produced cheaply there are a myriad of waiting applications waiting to be discovered.
Technology Brian Glassman
www.TechRD.com
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Guest (Karen)
my thoughts too
Brian:
I am not sure what "cheap" really means in terms of a mass market product. However I went to the same thought - that there are many more applications than robots for this type of product. I am wondering if conductive ink it possible to use vs. the gold layering?
Karen
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Guest (Brian Glassman)
"Alternative to Gold"
Thank you for the response Karen, I very much agree the word cheap is quite ambiguous, and the word cheap and gold does not go well together. I am going to take a guess why gold here. I am guessing it was chosen because it was easier to apply; it resists oxidation, highly conductive, and can be made very thin easily and bendable. Also as development continues on active cellulose films, it would only make sense (as you suggest) to search out new conductive substitutes for gold (like conductive inks and plastics).
The real meaning of the word cheap has to be put in the content of each application, for NASA cheap is space probe below $10Million, for an in store display cheap might be around $15 to $50 in parts and labor. As the price of this new active cellulose films reduces new applications will open up. Of course, a lower introduction cost will breed more applications for this neat technology, and why not try to make it low cost as possible.
Brian Glassman
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