Sophisticated cables are not just for RF: Page 2 of 2

March 21, 2016 // By Bill Schweber
Bill Schweber considers cables that must move and stretch and with two examples reflects that it's not "just some quality copper and insulation."

In very different part of the interconnect world, there's some fascinating work looking to leverage carbon nanotubes to build conducting fibers that can stretch by significant amounts. These may find use in applications ranging from exoskeletons to pacemaker leads (their most-common source of failure is their leads and attachment). Researchers at the University of Texas (Dallas) wrapped sheets of these tiny nanotubes as a sheath around a long rubber core, Figure 2, see "Scientists Stretch Electrically Conducting Fibers to New Lengths." Unlike conventional copper cables, where stretching the wire reduces the cross section and thus increases their resistance, there is little change in the resistance of these cables when stretched even by a factor of ten. (The 24 July 2015 citation and abstract of the academic paper in Science is " Stretch, wrap, and relax to smartness," but the full paper is behind their subscription wall.)

Figure 2: Researchers at the University of Texas have developed a very stretchable, electrically conducting fiber made of layers of carbon nanotubes and rubber that can bring performance benefits as a flexible, interconnect for pacemakers, and perhaps be the core of small-scale artificial muscles (University of Texas).

The applications go beyond the obvious. The researchers say these highly stretchable conducting fibers can be the basis (with added sheathing) for building strain sensors, as well as artificial muscles where the buckled nanotube shields act as electrodes, or even miniature torsional muscles if the fibers are twisted.

Of course, there's often a huge chasm to cross between a lab development and a practical product or technology for even niche, specialized applications. It's worth reminding ourselves that the apparently mundane role of a conducting cable actually plays a large part in successful, reliable designs. The advances of both researchers and manufacturing from DC to RF in materials, implementations, and configurations will have an impact that we may not appreciate, except in hindsight.

Have you ever had cables and interconnects be the gating item or your projects, or needed their technical innovation to complete the job?

Bill Schweber, is an engineer, author and editor and this article first appeared on EE Times' Planet Analog website.

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