03.02.2026

MRI relies on radio waves and strong magnetic fields, conditions in which conventional copper cables can heat up and distort images. This becomes critical when MRI is combined with EEG, ECG or temporal interference stimulation, where electrodes must be connected by cable inside the scanner. Empa reports polymer-based electrode cables with precisely defined conductivity and thin metal coatings.

Image: The photo shows two white braided cables with black connector; Copyright: Empa

Polymer-based electrode cables with thin metal-coated fibers are designed to transmit signals in MRI setups while reducing heating and image interference.

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Magnetic resonance imaging (MRI) produces high-resolution images of tissues and organs, helping clinicians identify small injuries, inflammation and early-stage tumors. Because the method uses radio waves and extremely strong magnetic fields, metal components can be problematic. Unless specifically designed, metallic objects, including implants, may heat up and cause burns, even if they are not strongly attracted by the magnetic field.

This challenge also affects multimodal setups where MRI is combined with:

ECG (electrocardiogram) for cardiac monitoring
EEG (electroencephalogram) for brain activity measurements
TI stimulation (temporal interference stimulation) targeting deep brain structures

In such cases, patients wear electrodes on the chest or head while in the scanner. The electrodes must be connected to measurement or stimulation devices, typically using copper cables, which can heat up and introduce artifacts into MRI imaging.

Polymer electrode cables with defined conductivity

Researchers at Empa’s Advanced Fibers laboratory in St. Gallen, together with industrial partner TI Solutions AG, developed electrode cables that are largely made of polymer fibers rather than copper. Instead of metal wires, bundles of polymer fibers are coated with an ultra-thin metallic layer to achieve a controlled, low conductivity.

“Our goal was to develop a cable with a very low but precisely defined metallic conductivity,” says Hegemann. “The conductivity must be high enough for the signal to be transmitted, but not as high as to interact with radio waves.”

TI Solutions develops electrodes for stimulating and measuring brain activity and specializes in TI and EEG, providing a direct use case for the collaboration within an Innosuisse project.

“With ‘MRIComplead’, the MRI-compatible cables developed in the Empa lab, our medical research partners now have the opportunity for the first time to visualize the effect of TI in the brain using MRI safely and without interference,” says Sven Kühn, Head of Research and Development at TI Solutions.

Durability, corrosion resistance and scalable manufacturing

Defined conductivity was only one requirement. For medical and research use, the cables also needed long-term durability and resistance to corrosion and mechanical stress, such as repeated plugging and unplugging.

The team tested around a dozen coatings and selected a thin film made of silver and titanium.

“Silver has very good electrical conductivity,” explains Hegemann. “Titanium reduces the conductivity somewhat so that we can achieve our specified range.”

The first coated polymer cables were tested over a year, with conductivity showing minimal change. The coating, less than half a micrometer thick, is applied via magnetron sputtering, a process compatible with industrial roll-to-roll manufacturing.

COMPAMED-tradefair.com; Source: Empa

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