Ice does not usually show up in conversations about electricity. A new study reports that ordinary frozen water generates electric charge when it bends, and the measured response is on the same order as benchmark electroceramics such as titanium dioxide and strontium titanate.

The research also links this behavior to how storms build up charge, offering a fresh way to think about why lightning starts inside clouds. It adds a surface twist at extremely low temperatures that could matter in special environments.

Ice and flexo-electricity

Scientists call this effect flexo-electricity, the coupling between electric polarization and strain gradients in an insulator. A comprehensive review explains why any solid can show some flexoelectric response when it is bent unevenly or shaped with strong curvature.

This is not the same as being piezoelectric, which requires a crystal structure that lacks inversion symmetry and creates charge directly under uniform compression or tension. Flexo-electricity does not need that symmetry break, so it can appear in materials that fail the piezoelectric test.

Dr. Xin Wen of the Catalan Institute of Nanoscience and Nanotechnology (ICN2), located on the Universitat Autonoma de Barcelona campus, helped lead the experiments and modeling. The team combined precise bending tests with theory to tie the electrical signal to the mechanical shape of the ice.

Testing a slab of ice

The researchers shaped an ice slab, placed it between metal plates, then bent it in a controlled way while monitoring the voltage that appeared. The signal tracked how strongly the slab curved, which is exactly what flexo-electricity predicts.

“We discovered that ice generates electric charge in response to mechanical stress at all temperatures,” said Dr. Wen.

The tests showed that ice keeps producing a strong electrical signal across the whole range of temperatures where it stays solid, right up until it melts. That puts frozen water in the same league as some engineered materials, like certain oxides, that are commonly used in electronic sensors and capacitors.

At extremely low temperatures, the researchers also noticed a very thin surface layer of ice that could flip its electrical orientation when an outside electric field was applied. This layer acts like a ferroelectric, but only on the surface and not throughout the entire block of ice.

Ice interacting with its environment

Surface structure can dramatically change how ice interacts with its surroundings. In thunderclouds, tiny ice crystals crash into soft hailstones known as graupel, and those collisions shift electric charge from one particle to another.

Studies in the lab and in real storms have shown that these encounters separate charge in ways that depend on temperature, building up the electric fields that allow lightning to form.

Flexo-electricity offers an additional microphysical pathway for those particles to charge up during bouncy, irregular impacts that bend and twist their surfaces. The new measurements match the scale of charge transfers inferred for real collisions, which helps knit lab physics to storm electrification without requiring piezoelectricity.

A clear overview from NOAA outlines how separate charge regions form in a storm, build an electric field, and finally trigger a lightning discharge. The present work slides a mechanical bending effect into that picture, adding a way for collisions to do electrical work when particles deform unevenly.

This matters most in the mixed phase region of a storm where supercooled droplets coat graupel and ice crystals ricochet through updrafts. Nonuniform stresses there are normal, so a bending driven mechanism is a natural candidate.

Ice powers new electricity tech

Ice is cheap to make, it molds into shapes easily, and it is abundant in cold places. Flexoelectric transduction could let engineers build simple sensors or pressure to voltage converters in situ, using water and metal contacts without high temperature processing or rare elements.

Devices would not be limited to extreme cold, since the flexoelectric response persists up to the melting point. Designs would focus on geometry, because stronger curvature and sharper gradients usually drive larger signals in flexoelectric systems.

The ferroelectric surface layer at about -171°F raises interesting options for switching behavior in deep cold. It could enable memory-like responses in polar regions or high altitude labs, where a modest electric field flips the surface polarization while the interior remains nonpolar.

Electricity lessons from ice

Flexo-electricity turns uneven bending into electrical charge, even in a material long treated as electromechanically quiet under uniform pressure.

Ice now joins the small set of everyday materials proven to convert mechanical shape changes into measurable voltage. In storm physics, it emerges as a credible new factor working alongside well-known non-inductive charging processes.

Charge generated by bending fits naturally with the chaotic collisions of particles, linking lab findings to the electric dynamics of real clouds.

The study is published in the journal Nature Physics.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–