Northwestern scientists put tiny particles in liquid under an electric field; they began moving together without touching, and the liquid carried the signals

Imagine hundreds of strangers all clapping in time. Now imagine doing the same, but on the scale of a human hair, with particles smaller than a speck of dust, dropped into a glass of liquid. It may sound unbelievable, but that is exactly what a team of engineers from Northwestern University has observed in a 2026 study, “Self-oscillating synchronematic colloids,” published in the journal Nature Communications. Tiny plastic spheres suspended in a liquid were placed in a steady electric field and moved. While scientists knew that single particles would oscillate, they were surprised to find that groups of particles started to move in time with one another.

The study was co-led by Olvera de la Cruz and Kyle Bishop, a chemical engineering professor at Columbia University, with Northwestern postdoctoral researcher Sergi Leyva serving as first author alongside Columbia’s Zhengyan Zhang. The particles used in the experiments are known as Quincke colloids, spheres that begin spinning or rocking on their own once a strong enough electric field is applied. The team built a simulation approach called Stokesian Dynamics, paired with an electrostatic model, to test the behavior computationally alongside physical experiments. They also found that in tightly packed, crystal-like clusters, the particles’ collective oscillation frequency actually increased as more particles joined the group, a result they attribute to non-reciprocal coupling between neighbours. The work was funded by the U.S. Department of Energy.

No contact, no communication, no leader


These particles do not come into contact with one another. The liquid they are suspended in acts as a form of communication between them. Every time a particle oscillates, small ripples are created in the surrounding liquid. This causes neighbouring particles to move, setting off a chain reaction that brings whole groups of particles into sync.

Senior author Monica Olvera de la Cruz, professor of materials science at Northwestern, admitted that they struggled for years to understand why this was happening. The team originally thought it might be due to the electric field. However, running simulations let them switch off the electrostatics entirely, something they could not do in the physical experiment, and the synchronisation still appeared. It was actually due to the fluid.

Why this matters beyond the lab bench

While this may seem like a cool physics fact, the researchers say this could provide a physical model for how coordination can occur in living systems. Whether it is fireflies blinking, heart cells, or flocks and crowds, researchers have long used shared mathematical models to study self-synchronisation in colloids, swarms, and biological systems, an approach laid out in the widely cited 2017 paper “Oscillators that sync and swarm” by applied mathematicians Kevin O’Keeffe, Hyunsuk Hong, and Steven Strogatz, also published in Nature Communications.

This does not mean that heart cells or fireflies use the same fluid mechanics as this study. Biology is complicated and messy. However, Orit Peleg’s research into fireflies, as documented in a 2022 Quanta Magazine publication, found that even fireflies are constantly surprising scientists. As more data is collected in the field, assumptions made decades ago are being disproven. Nature does not often give up all of her secrets!

The takeaway

The study demonstrates that particles do not need to be in contact, constantly communicating, or following a leader to move in time with one another. Sometimes the shared environment itself is enough to bring everything into rhythm. The researchers now want to see if this synchronisation can be increased or decreased, which could be useful in the future for creating microscopic machines and materials that can self-organise. For now, it stands as a reminder that coordination does not always require a conductor, sometimes a shared medium is all it takes.