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# SMART CLOTHES

THE TERM “dressing smart” used to mean a man’s natty decorative handkerchief in a blazer breast pocket or a woman’s fine pearls and simple black dress. The technology of smart fabrics broadens this meaning. The February 2018 issue of Tech Briefs features two innovative materials, one with mathematical patterns that harvest body energy, the other devised with security coding or other smart functions. Here are tidbits gleaned from these articles.

Thermoelectric clothing. Dr. Shannon Yee, a researcher at Georgia Institute of Technology, says, “My group has recently been looking at polymer-based thermoelectric (TE) materials to serve as the semiconductor elements for wearable TEs.” A key for this technology is found in the mathematics of Hilbert curves.

David Hilbert, 1862–1943, German mathematician, considered one of the most influential mathematicians of the 19th and early 20th centuries.

A Hilbert curve is a continuous fractal curve that fills space. Hilbert and Italian mathematician Giuseppe Peano discovered space-filling properties in 1890–1891. The idea of a fractal, an object exhibiting self-similarity at increasingly small scales, came much later in the 1960s when Benoit Mandelbrot formalized this idea of self-similarity.

Above, this Koch Snowflake isn’t space-filling, but exhibits fractal self-similarity. Below, this Hilbert curve is both space-filling and fractal. Hilbert curve image from scienceblogs.com.

Researcher Yee notes that a big challenge with heat-to-electricity TE materials is interconnecting their different elements. With Hilbert curves, it’s possible to create what he calls, “fractal-like geometries where sub-modules are repeated geometrically throughout the main module.”

These patterns can be printed over large areas of fabric. Then, notes Yee, “… you could literally come with a pair of scissors and cut the module to create the current and voltage you need for your application.” His group is also looking at classic knitting patterns to see how TE yarn could knit these modules directly into clothing.

A thermoelectric material converts body heat into only a meagre amount of electricity. Forget charging your cell phone. But think about a TE shirt’s embedded heart monitor or other biometric device being powered by nothing more than body heat.

Yee also suggests, “What I think is more exciting than generating electricity is the ability to run these in reverse and achieve cooling.” Battery-powered clothing could produce a personal cooling sensation, enough to lessen the loads of conventional room air conditioning.

Now that’s a cool way to dress.

Data-Stored Fabric. Researchers at the University of Washington, Seattle, have worked with a conductive embroidery thread that can carry magnetic properties.

Notes Tech Briefs, “Conventional sewing machines were used to embroider fabric with off-the-shelf conductive thread whose magnetic poles start out in random order. By rubbing a magnet against the fabric, the researchers were able to physically align the poles in either a positive or negative direction that can correspond to the 1s and 0s in digital data.”

The fabric can be washed, dried, or ironed without altering the stored data. “Like hotel card keys” Tech Briefs notes, “the strength of the magnetic signal weakens to about 30 percent over the course of a week, though the fabric can be re-magnetized and re-programmed multiple times.”

Shirt cuffs, for example, could be fabricated with these smart fabrics and, with periodic refreshing, would eliminate conventional security cards on lanyards.

Image by Dennis Wise/University of Washington, from Tech Briefs, February 2018.

The researchers are applying this technology to gloves with data-storage fingertips. Hand gestures yield different magnetic signals that can be perceived by electronic devices, cell phones, for instance, as left flick, right flick, click or back click, or upward or downward swipe.

And enjoy those magnetic fingers. ds

### 7 comments on “SMART CLOTHES”

1. Henry Nelson
February 10, 2018

“Yee also suggests, “What I think is more exciting than generating electricity is the ability to run these in reverse and achieve cooling.” Battery-powered clothing could produce a personal cooling sensation, enough to lessen the loads of conventional room air conditioning.”
Really?
All the cooling BTUs will be dumped into the room making the room hotter.

• simanaitissays
February 10, 2018

I admit I don’t know enough about TE clothing to comment. However, the Yee interview suggests a net benefit.

• jlalbrecht64
February 11, 2018

I agree completely. It would be like venting a portable air conditioner into the same room. It ends up actually hotter than before.

It would have external applications for hotter climates, particularly for non-contact sports. A golf shirt or shorts that cool would be awesome. A t-shirt to mow the lawn in Houston would sell well.

• simanaitissays
February 11, 2018

Again, I admit I don’t know enough about the TE mechanism to comment. However, consider that Yee is a professor at Georgia Tech.

• jlalbrecht64
February 11, 2018

I didn’t mean to imply I’m an expert in TE clothing, and I have no problem admitting I’m ignorant and happy to be corrected!

2. jlalbrecht64
February 10, 2018

Does Tech Briefs have an article about tech briefs?

• simanaitissays
February 10, 2018

Ha. Perhaps a “short(s)” article.

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