Why your protein shake clumps, and how Melbourne science could one day fix it

RMIT researchers have shown that static charge can be turned up, flipped or switched off with an electric field. Food powders are the next test.

Most people who drink protein shakes have chipped a stubborn lump out of the bottom of a shaker, or chased a floating clump around a mug of chocolate milk. According to researchers at RMIT University, static electricity is one of the likely reasons, and they have found a way to control it.

Scientists from RMIT and Riga Technical University in Latvia have shown that the static charge left on a surface can be controlled. RMIT says the discovery could help manufacturers avoid unwanted static when making everyday household goods, and might one day stop powders such as protein, chocolate malt and coffee from clumping.

A costly little zap

Static electricity is usually treated as a hazard. Industry often reduces it by adding expensive conductive additives, a one-size-fits-all fix. According to RMIT, static discharge costs the electronics industry alone about US$5 billion.

The new findings point to a different approach: surfaces whose static charge could be programmed to suit the job.

What the researchers found

The study was co-led by Dr Peter Sherrell from RMIT’s School of Science, in collaboration with Riga Technical University. It showed that applying an electric field while two surfaces touch and pull apart controls how much static charge is left behind. The field can also decide whether that charge is positive or negative, or remove it altogether.

The first author and co-corresponding author is Dr Andris Šutka of Riga Technical University. Professor Amanda Ellis from the University of Melbourne is a co-author, and PhD student Dumindu Dassanayaka and Dr Qiang Sun from RMIT were also key contributors.

Dr Sherrell gave the example of a conveyor belt sorting seeds, where the static charge changes with the size or species of seed. Adjusting the electric field for each species would mean “no risk of a seed getting a static shock”, he said.

Other possible uses include anti-static surfaces for manufacturing and electronics, controlling where charged particles or plastics stick and how they assemble, smarter sensors, and smart air and gas filters.

A smoother shake?

As powders rub and tumble during manufacturing, packing and pouring, the grains can pick up static charge and cling to each other.

“In principle, we could apply a small electric field across powders as they move,” Dr Sherrell said. That would stop the grains charging up, so they don’t get electrostatically “stuck” to each other.

The team tested plastics, not food. RMIT says the results are a good indicator of how the approach could work for food powders, and the next step is to find out how strong the field needs to be, how long to apply it for each powder, and where in the process it works best.

The researchers also plan to test real powders and to study programmable surfaces at much smaller scales, so different parts of one surface could be programmed differently. A current grant application with industry partners focuses on removing anti-static additives from fuels by tuning the surfaces the fuels touch, which could make fuel more energy efficient.

Solving a long-standing puzzle

The research also adds evidence to a question scientists have debated for years: what makes electric charge separate when two materials touch and pull apart?

Computer simulations showed that the fields the team applied were similar in strength to those created naturally when rough plastic surfaces press together. According to RMIT, this supports the idea that tiny built-in electric fields help drive everyday static electricity.

How the research was done

The team pressed polystyrene films together and pulled them apart 500 times while applying external electric fields. Stronger fields left more charge, and reversing the field from positive to negative reversed the charge. The same thing happened in every plastic tested. The results were then compared with computer models to understand what was happening.

The limits

The experiments were done in a lab on plastic films, mostly polystyrene. Protein, malt drink and coffee powders were not tested. The charge was set by applying a field during contact and measured afterwards, so switching the charge live, as in the conveyor belt example, has not yet been shown. The simulations used a simplified model, and the approach has not been tried on industrial equipment.

“The science would enable this to happen based on the discovery,” Dr Sherrell said.

Why it matters to you

For now, your shaker still needs a good shake. But if the approach works on real powders, the lumps in protein, malt and coffee could one day be a thing of the past.

The study, “Electric fields control static charge during contact-friction-separation”, is published in Nature Communications. It was supported by the Latvian Central Finance and Contracting Agency (ERC project TriboCharge) and an RMIT Vice-Chancellor’s Research Fellowship.

Sources: RMIT University, media release, 21 October 2026; Šutka, Sherrell et al., “Electric fields control static charge during contact-friction-separation”, Nature Communications, 15 October 2026 (DOI: 10.1038/s41467-026-77733-4).