Researchers Make Wearable Electronics as Simple as Ironing on a Patch

Researchers from Virginia Tech have developed iron-on circuits that, they say, could lead to easier-to-produce wearable electronics — and even the ability to functionalize existing garments quickly and easily.

"E-textiles and wearable electronics can enable diverse applications from health care and environmental monitoring to robotics and human-machine interfaces," says corresponding author Michael Bartlett of the team's development. "Our work advances this exciting area by creating iron-on soft electronics that can be rapidly and robustly integrated into a wide range of fabrics."

The idea of integrating electronics into fabrics isn't new, and it's not even beyond the reach of hobbyists: conductive thread allows you to use standard sewing skills, and even machine sewing, to add circuits to clothing. The patch-based approach developed by the Virginia Tech team, though, is even easier: just iron the circuit onto fabric, like a repair patch or decoration.

The patches are made from a mixture of polyurethane and a gallium-indium alloy, poured into sheets and allowed to air-dry over the course of a day — after which it forms a soft and electrically-conductive sheet. These sheets can then be ironed onto a range of fabrics, with woven polyester, cotton twill, knit spandex, and mesh jersey materials tested successfully, to form a strong bond once cooled.

To demonstrate example use-cases, the team built two proofs of concept. The first was a light-up version of the university logo featuring five LEDs, which remained lit even when the material was put through repeated folding, twisting, and stretching; the second was a stretchable wire microphone fitted inside a shirt, with an ironed circuit delivering power to the mic and audio signals to an external recorder. Future work, the researchers add, could include integrating the technology into more complex soft circuits and even robotic systems.

The team's work has been published in the journal ACS Applied Materials & Interfaces under open-access terms.