Researchers Develop a New System of Electrodes for Durable Smart Clothes

Researchers at the University of Oulu and VTT Research Center and Polar Electro have developed a new series of flexible electrodes that could be used to create durable smart clothing that could handle the rigors of everyday use, including being repeatedly laundered. The development of the electrodes coincides with tests to understand if different shapes and materials have a higher resistance to elongation (while wearing) and washing cycles.

“This work brings us one step closer to smart clothing ubiquity, where our apparel, in addition to monitoring our health and surrounding environment, will be changing its appearance and properties accordingly to our wishes,” explains professor Rafal Sliz, lead author on the newly released paper entitled “Reliability of R2R-Printed, Flexible Electrodes for e-Clothing Applications.” As the title states, the team employed R2R (roll-to-roll) printing techniques to produce flexible electrodes using conductive particles and elastomers, or other flexible materials.

The researchers produced several different electrode designs with varying shapes using different conductive pastes R2R printed on flexible substrates. The end goal of the electrode design is to use them for precise electrocardiography (ECG) and electroencephalography monitoring, which means they have to be in direct contact with the wearer’s skin. To that end, the team made a pair of products to undergo testing, including a device with the electrodes printed on a TPU substrate with a supportive carrier, and a flexible belt designed to take EEG readings.

Both the TPU device and belt underwent trials using a washing machine for reliability testing and elongation (stretching) to measure breaking points, after which, they were measured for performance and precision. The researchers found that pastes consisting of conductive particles of a size below ~8 µm produce reliable electrodes, but compromise their high conductivity and integrity after washing, while larger patterned electrodes offered better electrical properties. That said, they note there need to be further refinements and testing before they can be used in commercial markets.