Static electricity has long remained one of physics‘ most unpredictable mysteries. However, a new study from the Waitukaitis Group at the Institute of Science and Technology Austria (ISTA) may have finally brought order to the chaos.
The research reveals that materials’ electrical contact history determines how they exchange charge, offering a long-sought explanation for the randomness of static electric exchanges. Using identical materials, the team identified a previously unsuspected factor that controls charge transfer.
Static Electricity Mysteries
Static electricity affects everyday life in familiar ways—the shock from touching a doorknob, a balloon sticking to a child’s hair, or styrofoam clinging to a pet. Despite its ubiquity, scientists have long struggled to fully understand “contact electrification,” the process by which materials exchange charge upon contact.
“We colloquially refer to contact electrification as ‘static,’ but movement and contact are primary ingredients in the event,” explains Scott Waitukaitis, head of the Waitukaitis Group at ISTA.
“There is no escaping contact electrification; everyone experiences it. That’s why it might come off as a surprise to us that we don’t understand how exactly it happens,” he adds.
Waitukaitis led the research alongside ISTA PhD candidate Juan Carlos Sobarzo, who recalled the moment when the research team reached a turning point.
“We tested different parameters that might affect contact electrification, but none of them could soundly explain our results. That’s where we stopped to think: what if it’s contact itself that’s affecting the charging behavior? The word ‘contact’ is already in the name, yet it has been widely overlooked.”
The Strange Effects of Static Electricity
Physicists and chemists have puzzled over static electricity for centuries. While scientists understood how charge exchange worked in metals as early as the 1950s, the process remained unclear for insulators.
Over time, researchers proposed a “triboelectric series”—a ranking of materials based on their tendency to gain or lose electrons. However, inconsistencies plagued these studies. Different research teams produced conflicting orders, and even repeated experiments by the same scientist sometimes yielded different results.
“Understanding how insulating materials exchanged charge seemed like a total mess for a very long time: The experiments are wildly unpredictable and can sometimes seem completely random,” says Waitukaitis.
Further complicating matters, even identical materials exchanged charge unpredictably, leading scientists to question what determines the direction of charge transfer.
Minimizing Variables
To investigate, the team focused on identical-material contact electrification, which had proven to be the most unpredictable—and, therefore, the most revealing—form of charge exchange.
By eliminating as many variables as possible, they designed an experiment using polydimethylsiloxane (PDMS), a transparent silicone polymer. Their initial hypothesis suggested that random surface variations influenced charge exchange. However, early tests produced the same chaotic, inconsistent results as previous studies.
Determined to uncover the cause, the researchers tested whether individual PDMS samples would form a triboelectric series over time. That’s when Sobarzo made a surprising discovery.
“I took a set of samples I had at hand—back then I would reuse them for multiple experiments—and to my disbelief, I saw that they ordered in a series on the first try,” he recalls.
The Role of Contact History in Static Electricity
To confirm the finding, the team repeated the triboelectric series experiment with fresh, unused samples. The results? Randomness returned.
“At this point, we could’ve thrown in the towel,” says Sobarzo. “However, I decided to try again with this same set of samples the next day. The results looked better, so I kept trying until at the fifth try, the samples ordered into a perfect series.”
This breakthrough led the researchers to a critical realization: Repeated contact was altering the samples’ charge behavior over time. The reused samples had already undergone multiple charge exchanges, gradually shifting their electrical properties.
“As soon as we started keeping track of the samples’ contact history, the randomness and chaos actually made perfect sense,” says Waitukaitis.
Through further testing, the team found that after approximately 200 contact events, the samples began behaving predictably. Crucially, the sample with a longer contact history consistently charged negatively when paired with a newer sample.
Even more remarkably, their findings demonstrated that a triboelectric series could be intentionally designed simply by controlling the number and order of contacts between materials.
A Fresh Perspective on Static Electricity
The discovery of contact history as a determining factor in charge exchange is entirely new and helps explain why previous experiments produced such inconsistent results.
However, one question remains: What physically changes in the material during contact events?
The researchers examined several properties of their PDMS samples and found only one measurable change—microscopic alterations in surface roughness. Each contact subtly smoothed out tiny surface bumps, suggesting a potential link between mechanical wear and charge behavior.
Still, the exact mechanism remains unknown.
“We managed to reveal a big clue to an elusive mechanism that is so fundamental to our understanding of electricity and electrostatics and yet kept scientists puzzled for so long,” says Sobarzo. Waitukaitis concludes, barely able to hide his excitement, “We showed that the science of static electricity is not so hopeless anymore.”
The paper “Spontaneous Self-Organization of Identical Materials into a Triboelectric Series” appeared in Nature on February 19, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.