Medical Device Daily National Editor
"Wearable" monitoring halter-type rigs, vests or other types of clothing equipped with sensors to keep continuous track of physiological functions is a technology that overcomes the disadvantages of in-office monitoring, or any other type of repeated spot monitoring that only supplies occasional snapshots.
Traditional Holter monitors are worn by heart patients to track cardiovascular activity over long periods of time. Signalife (Greenville, South Carolina) is developing a cardiac "vest." And VivoMetrics (Ventura, California) has developed a similar vest-like wearable system called the LifeShirt for ongoing monitoring while the wearer is active.
Such systems offer the benefit of being non-invasive but may still provide occasional discomfort, if rubbing the skin, or may be a bit intrusive in other ways.
Now there is another potential entrant to the wearable monitoring sector though still at the very early-stage, basic science level out of the University of Michigan (UM; Ann Arbor).
Nicholas Kotov, a professor in UM's departments of Chemical Engineering, Materials Science and Engineering and Biomedical Science, has developed a "smart yarn," which can be formed into an "e-textile" that is lighter weight, less intrusive.
Kotov and doctoral student Bonsup Shim are two of the co-authors of a paper in a current online publication of Nano letters, describing the use of nanotechnology to treat basic fiber materials. The resultant "e-textile," they write, is able to conduct electricity, with the yarn capable of being woven into soft fabrics that detect blood and can be used in various ways to monitor physiological processes.
Kotov told Medical Device Daily that this electrically conductive material is a combination of several years of hard work and, once the basic engineering challenges were solved, ease of production.
He said that any type of yarn material can be used, and that carbon nanotube technology is becoming fairly common, with "a number of commercial suppliers" making these "almost a standard, off-the-shelf type of product." But he noted that the expertise in the use of carbon nanotubes particularly in the understanding and use of their conductivity has been 10 years in development.
The researchers created the e-textiles or 'e-fabrics" by dipping 1.5 mm-thick cotton yarn into a solution of carbon nanotubes in water and then into a solution of a special sticky polymer in ethanol. After being dipped just a few times into both solutions and dried, the yarn was able to conduct enough power from a battery to illuminate a light-emitting diode device.
Kotov said, "This turns out to be very easy to do. After just a few repetitions of the process, this normal cotton becomes a conductive material because carbon nanotubes are conductive."
He said that the simple method required to manufacture the material would ultimately translate to ease in scale-up for commercial applications.
In order to put this conductivity to use, the researchers added the antibody anti-albumin to the carbon nanotube solution. Anti-albumin reacts with albumin, a protein found in blood. When the researchers exposed the yarn infused with anti-albumin to albumin, they found that the conductivity significantly increased.
Kotov said that this new e-textile would have several advantages over the current types of smart textiles and their various drawbacks.
The traditional materials are "primarily of metallic or optical fibers," he said. "They're fragile. They're not comfortable. Metal fibers also corrode. There are problems with washing such electronic textiles.
"We have found a much simpler way, an elegant way, by combining two fibers, one natural and one created by nanotechnology."
He said the new nano/fiber combination material is more sensitive and selective as well as simpler and more durable than other electronic textiles.
"The concept of electrically sensitive clothing made of carbon nanotube-coated cotton is flexible in implementations and can be adapted for a variety of health monitoring tasks as well as high performance garments," he said.
"Of course, we are developing it in the direction of biological monitoring," Kotov told MDD. He said that he is currently working with a company on product commercialization, though he declined disclosing the company or the details of this collaboration.
But he did suggest a range of interesting possibilities for the new smart yarn and e-fabrics.
Such materials, he noted, might be medically useful by providing early warnings of injuries, for instance for those in high-risk professions and the military. In particular, the material's ability to sense blood could be used to alert emergency personnel concerning the distress of a downed firefighter, injured police officer or wounded soldier who is unconscious and unable to send a distress signal.
In addition to describing various possibilities for healthcare, Kotov proposed the development of a communication device, such as a mobile phone, that might transmit information from the clothing to a central command post. And he said it is "conceivable that clothes made out of this material could be designed to harvest energy or store it, providing power for small electronic devices."
He acknowledged that these applications are long-term possibilities putting the research halfway in development between initial proof-of principle and commercialization and would involve the development of other capabilities on the engineering side.
Commercialization, he said, "very much depends on the investment effort. If investment is high, we'll have the product on the market very fast."
The development of the fiber and resultant paper, titled, "Smart Electronic Yarns and Wearable Fabrics for Human Biomonitoring Made by Carbon Nanotube Coating with Polyelectrolytes," were developed in collaboration with Jiangnan University (Wuxi, Jiangsu Province, China).
This research was funded by the National Science Foundation (Arlington, Virginia), the Office of Naval Research, the Air Force Office of Scientific Research (Arlington) and the National Natural Science Foundation of China (Beijing).
The UM College of Engineering plays a leading role in the Michigan Memorial Phoenix Energy Institute and is home of the Lurie Nanofabrication Facility, providing facilities and equipment for research on silicon integrated circuits, MEMS, III-V compound devices, organic devices and nanoimprint technology.