Friday, January 25, 2013

A new tool for prototyping flexible photonics

Thanks to efforts by researchers at North Carolina State University, creating and developing prototype flexible photonics devices will become much easier.1 The NC State crew has created an extremely flexible and stretchable electrical wire that can be cut with a pair of scissors and then electrically and mechanically reattached simply by holding the ends together. Even more exciting, the wire ends can be cut at angles and pressed together in different combinations to form 2D and 3D networks for stretchable sensing arrays (medical and otherwise), wearable displays, and so on (limited only by your imagination, as they say).

(Image courtesy of NC State)

The wires consist of liquid metal within microchannels made of a self-healing polymer (see video for demo). The gallium-based conductive alloy at the wire's center is liquid at room temperature and, unlike mercury, is nontoxic. The wires should provide a simple way of 1) wiring up prototypes, 2) realizing you want these wires to go here, not there, and 3) spending a few seconds rewiring. And, considering that the NC State group has created wires of this type that can stretch eight times their original length, the resulting prototype can be very stretchable indeed.2

When cut, the gallium alloy forms an oxide surface at the wire's end that contains the gallium until wires are reattached. Another advantage of these wires; they can be made more conductive (by increasing the microchannel's inner diameter) without reducing their stretchiness, unlike other stretchable wires that have a solid conductor.

“Because we’re using liquid metal, these wires have excellent conductive properties,” says Michael Dickey, an assistant professor of chemical and biomolecular engineering at NC State. “And because the wires are also elastic and self-healing, they have a lot of potential for use in technologies that could be exposed to high-stress environments.”


1. Etienne Palleau et al., Advanced Materials, published online Jan. 18, 2013; DOI: 10.1002/adma.201203921

2. Shu Zhu et al., Advanced Functional Materials, published online: Dec. 13, 2012; DOI: 10.1002/adfm.201202405

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