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Subscribe to RSSNorthwestern University's Bartosz Grzybowski explains the mechanism behind contact electrification.
For millennia, scientists have puzzled over the reason why rubbing two insulators together can produce static cling — and you may be shocked to hear that the standard explanation is wrong.
Static electricity, also known as contact electrification, is "one of the oldest areas of scientific study," researchers from Northwestern University observe in their paper on the subject, published online today by the journal Science. Questions about the phenomenon's cause date back to around 600 B.C., when Thales of Miletus conducted experiments with amber charging against wool.
The traditional view was that electrons were transferred from the surface of one material to another — for example, from a plastic balloon to the strands of hair on a child's head. That would cause one material to carry a slight positive charge while the other material carried a slight negative charge. Because opposites attract, the hair would be drawn toward the balloon, resulting in that cute "bad hair day" look.
To test that explanation, the Northwestern team took an ultra-close look at the static-charged surfaces of plastic material as well as silicon and aluminum, using Kelvin force microscopy. What they found was different from what they expected. The surfaces were actually "mosaics" of electrically charged nanoscale regions, alternating between positive and negative charges. When the surfaces were rubbed together, tiny patches were transferred from one surface to the other.
"It's not just transfer of electrons when two pieces of material come together," principal study author Bartosz Grzybowski, a chemistry professor at Northwestern, told Science in a video clip. "It's about transfer of material that then mediates the buildup of charge."
When those nano-bits of material are torn away from the surfaces as a result of the rubbing, that breaks chemical bonds and leads to changes in the net electric charge of each material. So when you rub a plastic balloon on a child's head, tiny flecks of that balloon are actually being rubbed onto the little one's locks of hair.
"A picture that emerges is that contact electrification is a complex process involving a combination of, at least, bond cleavage, chemical changes and material transfer occurring within distinct patches of nanoscopic dimensions," the researchers write. "The exact relationship between these effects — and possibly also those due to the presence of surface water and local electric fields — remains unclear but prompts several intriguing questions for future research."
Grzybowski and his colleagues point out that contact electrification isn't just a parlor trick: Through the ages, the phenomenon has sparked technologies ranging from photocopying and laser printing to do-it-yourself biodiesel and spray painting. Grzybowski said his research group was already trying to apply what they've learned to come up with better ways to apply coatings to surfaces. So it's nice to know that even after 2,600 years of study, our view of contact electrification isn't ... heh, heh ... static.
More about electricity:
- Power beamed through the air
- Static buildup may explain Martian mystery
- Avoid getting burned at the pump — literally!
In addition to Grzybowski, the authors of "The Mosaic of Surface Charge in Contact Electrification" include H.T. Baytekin, A.Z. Patashinski, M. Branicki, B. Baytekin and S. Soh. For more about the research, check out this report from the Nobel Intent blog.
You can connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. Also, give a look to "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.
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This article is clear as mud. I guess that Jon Stewart is right when he says journalists are lazy. This article does little explaining and ends with a wise crack. It is a shame that true journalism doesn't exist anymore.
All the pertinent information is right there. The author assumed we would have a basic understanding of the concepts at play there.
The article discusses what is NEW in static cling study. What has been known in the past about rubbing the balloon on your head is assumed as common knowledge.
But how does this help me as I frantically pull clothes out of the drier in the morning as socks cling to the back of my shirt? (which is far better than my ladies panties clinging to my shirt)
They apparently leave some sort of pantie debris on you Tony. LOL
I used to be friends with two very senior television journalists ... I recall having long conversations with them ... dating back more than two decades ... lamenting the death of serious journalism. The cause is well know, though. News was once a subsidized trophy of television networks ... in a time when this bought them prestige ... when excellence was prized and they were far above the norm. In the 1980's, television news (other media followed) became profit centers at the same time that intellectual integrity and learning became passé ... watch the first ten minutes of the movie Idiocracy ... (warning more than 10 minutes will cause brain damage) ... it pretty well explains our future, I fear ...
I see no one is old enough to remember static cling and clothes dryer commercials.
Not only do I remember static cling in commercials ... I still find it in the dryer in cold weather :c) (as I recall fighting it was the original primary purpose of fabric softeners?)
I think I understand what he was saying. He is suggesting that it is the material exchange during the rubbing process that makes the for the charge transfer. I think that if you walk across a carpet, the material exchange would happen at your feet, yet the charge would happen on the door handle you would touch with your finger without the material exchange happening there.
No, what happens is you obtain a charge during the rubbing due to breaking bonds and transferring the materials to your feet. Now as long as you are insulated your body has a net charge, but the insulated state prevents current flow (think of how a bird sits on a power line without being shocked). As soon as you touch something of a different electrical potential (e.g. a grounded piece of metal such as a door knob) the charged particles cause current flow to balance the potential and you feel that current flow as a shock.
Basic grounding. Electrons will travel through your body but if you don't provide a way out they will stay there. The moment you touch the door knob you release the charge.
The electric explanation is not knew, what is new is the transfer of material. Almost implies that any two masses can be warped together by friction. The electrical charge is just a side effect. Energy release I guess.
Sorry it's not clearer, but I think Kalrune comes close. The key points, as far as I can tell, are (1) when you build up static electricity, it's not a simple transfer of electrons en masse from one material to another. Both of the materials involved are actually "mosaics" of positively and negatively charged regions. (2) What is actually being transferred is bits of material, measuring on the nanoscale, that carry a charge with them. (3) There may be something about the chemistry involved in rubbing the two materials together, but I have to warn you that I'm not on firm ground here. It has to do with "heterolytic bond breaking." Maybe someone else here can explain that further. In fact, maybe someone else here can explain the whole process better. It's clear that the researchers believe there are some issues that still have to be sorted out.
Someone else mentioned the triboelectric effect, and for that person's benefit, I'll quote the last sentence of the paper: "Finally, in light of our findings, it becomes clear why previous attempts to construct the so-called triboelectric series based on the 'average' material properties often gave ambiguous results - in reality, it is the nanostructure of the material's surface and the fluctuations in this structure that determine the macroscopically observed charging trends."
Kelvin force microscopy is measures more than one effect simultaneously, so it may not be possible to determine exactly what is going on, yet. I would expect a flurry of publications over the next year which test out this effect using a variety tests on the nano scale.
such a wondrous world we enter when we delve into quantum physics .... and this is where we are now ....
Otherwise, Yay!!!!! Balloons!!
Monotonous.
Peace,
OldHippieDude
Hey, I'm just glad that there is SOME mainstream science coverage - even if it's less than perfect. There's THOUSANDS articles about Wiener's Wiener (which is pretty much a non-issue) and yet when we finally figure out what makes Static Electrification actually work - it'll get passed over by most mainstream media.
So, not perfect coverage, but better than nuthin'!
Is this not the triboelectric effect?
I tried some experiments with balloons in the past that made me realize the old explanations were inadequate. For example, anyone can do this one. The next time you have a party and have helium filled rubber balloons, either wait for the helium to disapate enough for the balloons to become static lifting, or just add some weight to the string. The static state is best for this experiment. Rub the balloon to charge it then while it is relatively motionless in the air, place your hand next to it. You will find that the balloon has a relatively small charged area that it rotates toward your hand. This proves that the balloon is not charged all over. Furthermore, the strength of the charge should indicate how much material is present on the balloon to create the observed applied force, which is considerable; more than just a few atoms worth, so I still believe the explanations are insufficient.
I'm so happy that this is finally being cleared up.
'So it's nice to know that even after 2,600 years of study, our view of contact electrification isn't ... heh, heh ... static.'
... oh no you did not say that! :P
These results are going to have to be replicated and verified at other labs before they are going to be widely accepted....
This is a BLOG not a formal news site. And yes, the author(s) on Cosmic Log do generally assume at least a minimum level of knowledge about various sciences, a fact that I appreciate since it means I do not have to wade through tons of boring basics to get the gist.
So, let me get this straight; the scientific community has discovered, after centuries of just knowing they were right, that after all, they've been wrong all this time? About something so prevalent, so simple, so observable as... static electricity?
And these guys expect me to believe their erudite tomes about an event that supposedly occurred 14 billion years ago, at a place no one knows and that cannot be observed? Big Bang? Black holes? Dark matter? Riiiiiight!
Okay, now that I've had that bit of FUN, I'd better state for the record, than I'm just kidding, not trying to dispute the theories of science. Just couldn't resist the irony of that one! :)
Actually, if you go to ultrawavetheory.com you will find that they truly don't know the basics yet.
Leon Stark
Not so sure I fully agree with the findings. For instance - What if the static charge actually jumps through the air before your finger actually touches something, like when a person reaches for one's pet cat. I can't tell you how many times my cat gives me "the look" after being shocked by me b4 I actually touch the cat.
Where are the nanoparticals jumping based on friction when their is no actual friction to cause the particals to rub off? I'm not fully understanding the explanation unless the static occurs during an actual contact of two different charged surfaces.