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Holy Hemihelix! Scientists Discover a Bizarre Twist

Researchers learn how to create a natural helix that looks like a tangled telephone cord — and that could lead to new kinds of nanocircuitry.
Image: Helix and hemihelices
This is an illustration of a helix (top), a hemihelix with one "perversion" marked by an arrow (middle), and a hemihelix with multiple perversions (bottom). The black scale bar indicates 5 centimeters (2 inches) for each image.Jiangshui Huang

Researchers have figured out how to create a natural helix that looks like the tangle in a telephone cord — and that discovery could lead to new kinds of nanocircuitry.

The new twist is called a "hemihelix," and it's not really that new. All you need to do to create a hemihelix is twist your phone cord the other way until you get an awkward kink. But can you create materials with natural built-in kinks?

Scientists at Harvard say yes, and they explain how they did it this week in the open-access journal PLOS ONE.

Image: Helix and hemihelices
This is an illustration of a helix (top), a hemihelix with one "perversion" marked by an arrow (middle), and a hemihelix with multiple perversions (bottom). The black scale bar indicates 5 centimeters (2 inches) for each image.Jiangshui Huang

The researchers stumbled upon the hemihelical shape while they were trying to fabricate rubber springs for an imaging project. They took rubber strips of various lengths and widths, stretched them out and glued them together to create elastic coils.

"We expected that these strips of material would just bend — maybe into a scroll," materials scientist David Clarke said in a Harvard news release.

Instead, they discovered that the results were more variable than they expected. When the strips were wide relative to their length, the coil naturally turned into a helix like a telephone cord. But at different width-to-height ratios, the coil transitioned into a hemihelix.

Kinky, right?

Actually, knowing how to make natural hemihelixes could come in handy, said Katia Bertoldi, a materials scientist and one of the study's co-authors.

"If you engineer materials correctly, then you can get a variety of shapes and predict how they will look," she told NBC News. "Devices with more complex shapes could be produced."

Such devices could propagate light in unorthodox ways, potentially suggesting new twists for nanoscale sensors, resonators and electromagnetic wave absorbers. Researchers are already interested in the effects produced by tiny gold wires shaped like a helix. Just wait until they latch on to the hemihelix.

Jia Lui and Jiangshui Huang are the lead authors of "Structural Transition from Helices to Hemihelices," published in PLOS ONE. Bertoldi, Clarke and Tianxiang Su are co-authors.