New research out of Washington State University shows the glittering, serpentine structures that power wearable electronics can be created with the same technology used to print concert t-shirts.
The work shows that electrodes can be made using just screen printing to create a stretchable, durable circuit pattern that can be transferred to fabric and worn directly on the skin.
“We wanted to make flexible, wearable electronics in a way that is much easier, more convenient, and lower cost,” said co-author Jong-Hoon Kim, Associate Professor at WSU. “That’s why we focused on screen printing: it’s easy to use. It has a simple setup, and it is suitable for mass production.”
Currently, the commercial manufacturing of wearable electronics requires expensive processes involving clean rooms. While some use screen printing for parts of the process, the new method relies strictly on screen printing.
The study, published in the ACS Applied Materials and Interfaces journal, details the electrode screen-printing process and demonstrates how the resulting electrodes can be used for electrocardiogram monitoring (ECG).
The team used a multi-step process to layer polymer and metal inks to create snake-like structures of the electrode. The resulting thin pattern appeared delicate, but the electrodes were not fragile: They could be stretched by 30 percent and bent to 180 degrees.
Multiple electrodes are printed onto a pre-treated glass slide — allowing them to be easily peeled and transferred onto other material. After printing the electrodes, the researchers transferred them onto an adhesive fabric that was then worn directly on-skin by volunteers. The wireless electrodes accurately recorded heart and respiratory rates, sending the data to a mobile phone.
The study focused on ECG monitoring, but the screen-printing process can be used to create electrodes for a range of uses, including those that serve similar functions to smart watches or fitness trackers.
The team is currently working on expanding the technology to print different electrodes as well as entire electronic chips — and potentially whole circuit boards.