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Nanotextiles

Juan Hinestroza is an assistant professor of fiber science and directs the Textiles Nanotechnology Laboratory at the College of Human Ecology at Cornell University.

Juan Hinestroza is an assistant professor of fiber science and directs the Textiles Nanotechnology Laboratory at the College of Human Ecology at Cornell University. His field of research falls at the cross section of fiber and polymer science and nanotechnology. This makes Professor Hinestroza one of the world’s top authorities on nanotextiles. Below, he tells us how a regular ole pair of pants may one day be able to prevent disease, tell you how much longer you should be on the treadmill, and automatically wipe your ass. Just kidding about that last one (we hope).

With any luck, in the not-so-distant future our clothes will be engineered on the nanoscale. This will allow us to integrate textiles with unprecedented properties. Scientists can already produce tiny swatches of nanofabric by manipulating a material’s surface and adding nanoparticles, nanorods, and nanotubes, but wearable garments may soon be a reality.

Using nanotechnology, manufacturers will someday be able to develop textiles that repel water, kill bacteria, and conduct electricity. They will also be able to make clothing that detects the wearer’s heart rate, pulse, and blood pressure, as well as electrically active clothing that can change temperature. Nano-engineered bedsheets could monitor your vital signs while you’re asleep or unconscious without the tubes and other cumbersome equipment medical professionals use today. Another example is athletic wear embedded with sensors that can give the wearer all sorts of feedback about his or her workout.

It is currently impossible to manufacture these types of garments because there is still so much to understand about the science of nanoparticles. Scientists at Cornell, however, are developing the technology that may one day serve as the basis of large scale nanotextile manufacturing. By coating small amounts of cotton fiber with nanoparticles, and making this natural polymer electrically conductive, these scientists can graft the nanoparticles to the cotton. The graft is performed layer by tiny layer, particle by particle, all while maintaining tight control over the distance between individual particles. First a negative group is created on the surface of the nanoparticles, and then a positive charge is injected into the polymer. Finally, the positive charge itself assembles with its negative counterpart at the molecular level. In other words, it’s assembled one molecule at a time. Eventually, this technique creates a layer of about 200 nanometers on top of the cotton fiber, allowing the swatch to conduct electricity. Of course, something this small cannot be seen, touched, or sensed.

Working at such a tiny scale presents challenges when it comes to actually probing the surface of a material at the nanoscale. Using a new technique called Acoustic Force Atomic Microscopy, the Cornell team is able to understand nanoscale topography. AFAM involves sending a sound wave through a given sample and measuring the speed of the wave on the other side. It can be used to determine which part of a fiber is stronger than the other, down to plus or minus 15 nanometers, while other techniques are in the order of microns or millimeters.

One way to create individual atom deposits on the surface of a textile is a process called Atomic Layer Deposition. It’s the same technique used to create the electric circuits in your computer or cell phone. Using ALD, scientists can create metals and metal oxides that are only a few angstroms thick. These materials are extremely clean, and because the process takes place in a vacuum it’s possible to coat very intricate shapes and place a single atom on a particular fiber. For instance, scientists at Cornell developed a fabric that effectively fights many kinds of harmful bacteria by tightly and precisely arranging the particles of a nanotextile. On exposure to the fabric, only a fraction of the bacteria survives.

There is also massive potential for nanotextiles as a medical tool. An example is a type of fabric that detects specific allergens or toxic material, which could protect people from unhealthy environments. Another is a garment that could tell patients exactly when to take their medicine—or even provide the medication through the textiles.

Then there are myriad applications to the world of fashion. Imagine clothing that creates color by manipulating light—using no dye whatsoever. It could change from blue to red to yellow just by controlling the space between particles. If you get sick of a particular black shirt—abracadabra—your shirt turns white. The implications for fashion are limitless.

To learn more about nanotextiles go to nanotextiles.human.cornell.edu.