Elastic circuit connectors designed for rubber-band-like circuits

July 10, 2007 By Lisa Zyga feature
Elastic circuit connectors designed for rubber-band-like circuits
This stretchable thermometer can wrap around a patient’s forehead like a headband thanks to the horseshoe-shaped metal wires, which can stretch up to twice their normal lengths. Credit: Jan Vanfleteren, et al. (TFCG Microsystems Lab-Ghent University).

Researchers from Belgium have devised a plan for making headway into the area of flexible, washable electronics. These integrated electronics, which could be incorporated into clothing and biomedical applications, require all connections between components to stretch like rubber bands while maintaining their conductivity.

The researchers, Dominique Brosteaux, Fabrice Axisa, Eva De Leersnyder, Frederick Bossuyt, Mario Gonzalez, and Jan Vanfleteren, of the Interuniversity Microelectronics Centre and Ghent University in Belgium, have recently designed and fabricated elastic interconnections that can stretch to more than twice their original lengths (a 100% stretchability). Their results are published in a recent issue of IEEE Electron Device Letters.

Elastic circuit connectors designed for rubber-band-like circuits
A goal of the SWEET project is to design electronics that are not only elastic, but also washable, as demonstrated by this water-resistant, stretchable LED circuit. Credit: Jan Vanfleteren, et al. (TFCG Microsystems Lab-Ghent University).

“For biomedical and textile applications, the comfort of the user will be enhanced if the electronic circuits are not only flexible, but also elastic,” the researchers explained in their study. “Biomedical applications include implantable devices and electronics on skin.”

In the paper, the scientists describe how they constructed 3-cm-long elastic connectors by embedding 4-micrometer-thick gold wires in a highly elastic silicone film. The wires were coated with a 2-micrometer-thick nickel layer for soldering wires to the ends.

“Besides this construction, our team has also been developing alternative versions of this technology based on the same molded interconnect device (MID) technology,” Vanfleteren told PhysOrg.com. MID can combine electrical and mechanical functions on a single unit, replacing the conventional circuit board.

The group patterned the gold wires onto a substrate in a “horseshoe”-shaped form, which significantly reduced the stress compared with an elliptical shape, while maintaining the initial electric resistance. The horseshoe shapes were then connected to create a wave-like pattern. To further increase the elasticity, the researchers found that splitting the wire conductor track into four thinner (15-micrometer-wide) tracks greatly minimized the induced stress.

The researchers then tested a variety of different shaped connectors by stretching them to the point of electrical failure, which is caused by a rupture in the metallic track. The best connector stretched from 3 to 6 centimeters without losing conductance. However, all interconnections—even those that experienced electrical failure—recovered their conductance when they returned to their normal length.

Currently the group is developing technology toward the incorporation of the elastic interconnections into full electronic circuits. This goal is being pursued by three projects: BioFlex (Biocompatible Flexible Electronic Circuits) with funding by the Institute for the Promotion of Innovation by Science and Technology in Flanders; STELLA (Stretchable Electronics for Large Area Applications) with funding by the European Commission; and SWEET (Stretchable and Washable Electronics for Embedding in Textiles) with funding by the Belgian Science Policy.

“At the moment we’re focusing on the following applications: implantable electronics, smart textiles (with integrated stretchable circuits), and smart band aids (e.g. measuring physiological parameters that should follow skin deformations),” Vanfleteren said, adding that further details remain confidential at this time.

The latest developments of the group on stretchable circuits can be found on their Web page:

Citation: Brosteaux, Dominique, Axisa, Fabrice, Gonzalez, Mario, Vanfleteren, Jan. “Design and Fabrication of Elastic Interconnections for Stretchable Electronic Circuits.” IEEE Electron Device Letters, Vol. 28, No. 7, July 2007.

Copyright 2007 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

Explore further: Barnacle busting: Research targets ship biofouling

Related Stories

Barnacle busting: Research targets ship biofouling

October 13, 2016

Individually, tiny barnacles pose little threat to hulking U.S. Navy ships. But when clustered in thick clumps on a vessel's hull—a natural occurrence called biofouling—these sticky crustaceans can slow the ship and increase ...

UA engineers twist physics laws to boost sonic science

August 17, 2016

For decades, advances in electronics and optics have driven progress in information technology, energy and biomedicine. Now researchers at the University of Arizona are pioneering a new field—phononics, the science of sound—with ...

Checkerboard surface put to flexible electronics test

December 13, 2012

(Phys.org)—Interest mounts in stretchable electronics, seen as the future direction in mobile electronics. How long before manufacturing giants load retail shelves with devices that have stretchable electronics is anyone's ...

Recommended for you

Microsoft aims at Apple with high-end PCs, 3D software

October 26, 2016

Microsoft launched a new consumer offensive Wednesday, unveiling a high-end computer that challenges the Apple iMac along with an updated Windows operating system that showcases three-dimensional content and "mixed reality."

Making it easier to collaborate on code

October 26, 2016

Git is an open-source system with a polarizing reputation among programmers. It's a powerful tool to help developers track changes to code, but many view it as prohibitively difficult to use.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.