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Detection Technology Smarter Than the Average Fabric

    R&D DIGEST      

A light-emitting diode is powered through the strands of conductive thread from cotton. (Photos courtesy of BONG SUP SHIM)
Using a few simple steps, cotton threads are transformed into smart fabric that can detect proteins in blood. The finished result isn't a regular piece of thread but rather a carbon nanotube–coated yarn that conducts electricity. Researchers are hoping this could lead to smart garments used as a detection device in the field for high-risk professions such as military or law enforcement.
“There are no examples of conductive yarns made from cotton,” says Nicholas Kotov, PhD, professor of chemical and biomedical engineering and materials science at the University of Michigan (Ann Arbor). “There [are] also no examples of biosensors made from conductive fibers and no examples of blood-monitor[ing] cloths.”
Kotov worked on the project with researchers from the University of Michigan and Jiangnan University in China. A paper about the material they developed has been published in the November 2008 online version of Nano Letters.
Conductive cotton threads can be impregnated with carbon nanotubes, such as those shown here.
The research team made the conductive fabric by dipping cotton yarn, about 1.5 mm thick, several times into a carbon-nanotube-in-water solution, followed by a sticky polymer in ethanol. Once dry, the yarn conducts enough electricity from a battery to power a light-emitting diode. Using the carbon nanotubes transforms regular cotton into a conductive material.
“This turns out to be very easy to do,” says Kotov. “After just a few repetitions of the process, this normal cotton becomes a conductive material, because carbon nanotubes are conductive.” Using the combination fabric could tackle the problems inherent in other smart textiles, which include corrosion, fragility, and difficulty upon washing.
Kotov is working with fairly large pieces of fabric—enough to make a dress—and says there's no limit to its dimensions. It's possible that the fabric could be used either in the form of a small piece attached to a garment, or it could be woven into an entire piece of clothing. It is too early to determine at this point in the research.
This is a scanning electron microscopy image of conductive fabric.
Although its use in a hospital won't be ruled out, Kotov sees more value in using the technology in the field. For example, the smart material would somehow be connected to the radio used by soldiers, police, or others in a high-risk profession, and would send an automatic distress signal as soon as the fabric detects blood. It could also monitor heart rate or other functions related to electrical signals.
The capabilities of the fabric now need to be evaluated. Further developments include improving its conductivity and its ability to target certain proteins in response to specific conditions. Such targeting ultimately depends on its specific application. Because a sensor will be developed from the fabric, its wearability and longevity must be assessed as well. The researchers also need to examine any safety concerns surrounding carbon nanotubes and their interaction with humans.
The research was funded by the National Science Foundation, the Office of Naval Research, the Air Force Office of Scientific Research, and the National Natural Science Foundation of China.
Copyright ©2009 Medical Device & Diagnostic Industry
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