Static electricity is so common that it may seem simple. Rub a balloon against your head and the transfer of charges will make your hair stand up. Shuffle your feet on a carpet, and the load imbalance you produce may shock an innocent bystander.
So it might come as a surprise that static electricity – which results from what researchers in the field call the triboelectric effect – has left scientists scratching their heads for centuries. Some basics are clear. Materials transfer charges when they are rubbed or come into contact with each other: one becomes more positively charged and the other more negatively charged. Opposite charges attract while like charges repel, and voila, you have an elementary school science experiment.
But almost everything else in this area remains confusing. Is it the electrons, the ions or the pieces of matter that transfer the charge? Why do some materials charge positively and others negatively? What happens when two samples of the same material come into contact? For example, when you “rub a balloon on a balloon,” explains experimental physicist Scott Waitukaitis of the Austrian Institute of Science and Technology in Klosterneuburg. A big part of the problem is that experiments tend to misbehave, with the same procedures producing different results.
On supporting science journalism
If you enjoy this article, please consider supporting our award-winning journalism by subscribe. By purchasing a subscription, you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Today, researchers are solving some of the puzzles that have long plagued the field. Using sophisticated laboratory facilities that carefully control compounding factors, Waitukaitis and his team have discovered that the charge of certain materials has a strange tendency to depend on their past interactions. This week in NatureWaitukaitis and colleagues report that carbon-bearing surface molecules may play a role in guiding how charge is exchanged.
The findings “are the best work done in a very long time” in this field, says Daniel Lacks, a chemical engineer who studied triboelectricity at Case Western Reserve University in Cleveland, Ohio. Other teams are studying how surface area and velocity upon impact might govern charge transfer, and how the breakdown of chemical bonds contributes.
The influx of research appears to be driven by a desire to examine the fundamental physics at play, says Laurence Marks, a materials scientist at Northwestern University in Evanston, Illinois. A better understanding of the science of static electricity could lead to improved devices that use it to power remote sensors or battery-free wearable technologiesFor example. It could also help prevent electrical discharges that could cause industrial explosions.
According to the researchers, it is becoming increasingly clear that static electricity is far from a simple phenomenon that follows a clear set of rules. Instead, each fee exchange could be shaped by several factors that vary depending on the circumstances. Some of these factors are now known and others still await discovery.
Ancient observations
The history of static electricity dates back at least to the ancient Greek period. Triboelectric includes the Greek words for “rubbing” and “amber,” because once amber is rubbed against fur, it attracts light objects such as feathers. At the end of the 16th century, the English physicist William Gilbert identified other materials with the same attractive power, including glass, diamonds and sapphires, and distinguished this type of electrical attraction from that of magnetism. Over the centuries that followed, scientists learned that lightning was an electrostatic dischargea supersized version of the benign zap obtained by dragging your feet on a carpet, and invented the first electrostatic generators – precursors to the Van de Graaff generators that amaze students at science museums.
By the mid-18th century, researchers had also begun to document which materials became negatively charged and which positively, producing lists called triboelectric series. These rank materials from most likely to charge positively to most likely to charge negatively, with rabbit fur at the top and silicon at the bottom, for example.
There was a lull in efforts to understand the phenomenon for part of the 20th century before interest re-emerged at the turn of the 21st century. Marks attributes this renewed interest, at least in part, to the invention of the triboelectric nanogenerator. This device relies on the triboelectric effect to convert mechanical energy into electricity. It has attracted researchers interested in new ways to power small technologies. “Over the last ten years, this field has literally exploded,” says Giulio Fatti, a mechanical engineer at Imperial College London.
However, even with the increased attention, the fundamentals of triboelectricity have remained elusive. There are some generally accepted ideas, says Marks. A material has a specific potential for leakage of a charged particle which depends on the surface area and composition of the material. This potential is called the work function of the material, and so far it applies best to metallic materials, Waitukaitis explains. A sample must also be able to trap charged particles, so that they are held in place when the materials separate after exchange. But physicists are still trying to elucidate the exact mechanisms at the origin of these phenomena.
Other contact details also appear to matter. But what matters most, under what circumstances and for what materials, remains unclear. According to Marks, whether triboelectricity can be explained by existing physics or whether it requires its own model remains an open question.
Looking to the past
Waitukaitis and his team were studying how samples of the same material can exchange charge when they encountered inconsistent results that have long frustrated researchers in the field. Triboelectric series are difficult to reproduce. The teams have had varying results on which materials become more positively or negatively charged, and even different results with the same samples.
Waitukaitis tasked Juan Carlos Sobarzo, then a doctoral student, with attempting to form a series using samples of the same silicone-based polymer. But Sobarzo failed to achieve consistent results. In one experiment, sample A would become negatively charged upon interaction with sample B. In the next, it would become positively charged.
“For the longest time, we thought we were doing something wrong,” Waitukaitis says. “We thought there was a variable we didn’t control.”
Even when the team carefully controlled humidity — because the researchers believed that water on a material’s surface could affect how it charges — the results remained puzzling.
Next, Sobarzo dug up a set of samples that had already been extensively experimented with and tested how they interacted with new ones. The researchers quickly noticed that samples that had undergone more contact tended to become negatively charged. In other experiments, they tracked the number of contacts each sample had already experienced.
“That’s when things started to make sense. The samples that had the most contact in their history were always negatively charged,” Waitukaitis says. “What looked like chaos was an indication of how the samples were evolving.”
The researchers suspect that this evolution is linked to the way the surface of the sample deforms with each contact.
In the current paper, Waitukaitis, together with Galien Grosjean, an applied physicist at the Autonomous University of Barcelona, Spain, and their colleagues, studied more deeply how charges are exchanged between two seemingly identical materials. This time, they worked with oxides – materials, like sand, made of atoms bonded to oxygen – and used several technologies, including a device that levitates samples to prevent their charge from changing. They also used a high-speed camera to precisely measure the charge of the samples.
Before the experiment, scientists thought that water on the surface of materials could affect charge exchange. But samples stored in a humid or dry environment don’t seem to be noticeably affected. Next, the researchers baked the materials and found that cooked samples tended to charge negatively after contact and uncooked ones, positively.
After exploring the materials’ interfaces, the researchers realized that the baking process changed the results by removing carbon-carrying molecules on the materials’ surfaces. These types of molecules, like methane, a carbon-rich greenhouse gas, are typically captured in the air. They “slowly but surely settle on all surfaces,” Grosjean explains. The results suggest that the material is more likely to become positively charged after contact if it contains a greater number of carbon molecules on its surface.
Waitukaitis says the team did a double-take after discovering it was the carbon-carrying molecules at play. “You rarely hear about these molecules in the field of static electricity,” he says.
These results constitute the first steps towards understanding the factors that most influence charge transfer. So far, the contact history results appear to only apply to polymeric materials such as plastics, while the latest results apply only to oxides.
Nonetheless, the work indicates that there is no single answer to how materials are priced. “The idea of permanent triboelectric order between different materials is a mirage,” says Waitukaitis.
That such small factors can have such an impact isn’t necessarily a new idea, Lacks says. “But what is completely new are these really systematic experiments aimed at proving that a particular contaminant plays a determining and controlling role,” he adds. The field “has moved away from hand waving and toward more scientific proof.”
Zapping forward
Other groups are doing their own sorting out. South Korean researchers, for example, reported that they could control charge transfer by manipulating a material’s internal electric field. “This was significant because triboelectricity has long been considered largely uncontrollable,” says study co-author Sang-Woo Kim, who studies triboelectric energy harvesting at Unive rsity Yonsei of Seoul. According to Marks, the results match existing electromagnetic principles, suggesting that triboelectrification does not need a new set of rules. And a German team found that as the impact speed between two colliding metals increases, the impact surface area also increases, which can affect charge transfer. The link between impact speed and load transfer had been the subject of debate.
Fatti and his collaborators studied triboelectricity and chemical bond breaking, finding that a metal can break chemical bonds on the surface of a polymer when the two materials interact. This instability creates the ideal chemical conditions for electrons to be exchanged to re-stabilize the bond. The results, reported last January, could help researchers create more efficient triboelectric nanogenerators, they say.
Further research could also help prevent electrical discharges that cause damage or trigger explosions, for example in industrial factories. Other applications include controlling the charge contained in materials through 3D printing to create a temporary electrical equivalent of a permanent magnet and assessing the damage that the Moon’s prolific dust could cause. future lunar base camps.
Marks says that since he started working in this field in 2018, he has noticed that more and more physicists and chemists are applying “deep analysis” to static electricity, making painstakingly careful measurements.
Waitukaitis agrees that more and more labs are “being cautious” in their experiments. “Then these labs share the techniques that helped them with other labs,” he says. It’s still a small, tight-knit group of scientists who hold one dedicated conference a year – even as they try to spread their enthusiasm for triboelectricity. ty during larger physics meetings.
Now that groups are beginning to identify the most important parameters for certain charge transfers, Waitukaitis hopes that physicists’ understanding of the phenomenon will be completed. “I’m not sure we’re simplifying things,” he adds. “But we’re doing what we need to do to make sense of it.”
This article is reproduced with permission and has been published for the first time March 18, 2026.