Stretchable optical circuits could find use in robot skin and more
By Ben Coxworth
February 19, 2014
If flexible electronic devices are ever going to become practical for real-world use, the circuitry incorporated into them will have to be tough and resilient. We're already seeing progress in that direction, including electrical wires that can still carry a current while being stretched. However, what if the application calls for the use of fiber optics? Well, scientists from Belgium may have that covered, too. They've created optical circuits utilizing what they believe are the world's first stretchable optical interconnections.
The idea is that devices such as wearable sensors or touch-enabled robot skin could utilize standard glass fiber optic cables for the most part, but could use the interconnections to bridge gaps between those cables, allowing the device to bend or lengthen at those locations.
Made from a clear rubbery substance known as PDMS (poly-dimethylsiloxane), the interconnections feature a transparent core through which the light travels, that's surrounded by an outer layer of the same material. Because light doesn't move as easily through that outer layer due to its lower refractive index, the design keeps the light signals contained within the core.
In lab tests, the interconnections were able to guide light signals when stretched by up to 30 percent, or when bent around an object with a diameter as small as that of a human finger. What's more, they maintained that functionality after being mechanically stretched by 10 percent a total of 80,000 times.
The interconnections were developed at the Centre for Microsystems Technology, which is a laboratory associated with Belgium's Ghent University and the imec micro-electronics research center. A paper on the research was recently published in the journal Optics Express.
Source: The Optical Society