Monitoring Life, One Breath at a Time
Respiratory sensor may provide new tool for emergency responders
Arlington, Va.—Researchers have created a tiny device that can monitor a victim's breathing in emergency situations by effectively shrinking an operating room machine into a small, disposable tool that can be carried to a disaster site.
NSF-supported researchers at Nanomix, Inc., in Emeryville, Calif., have created a transistor that fuses carbon nanotubes, polymers and silicon into a capnography sensor -- a human breathing monitor.
Alexander Star and his colleagues at Nanomix and the University of California, Los Angeles, describe the new sensor in the cover article of the November 15 issue of the journal Advanced Materials. Their study shows that carbon nanotube transistors fused with carbon dioxide-detecting polymers can determine carbon dioxide (CO2) concentrations in both ambient and exhaled air.
Capnography sensors detect subtle changes in the concentration of carbon dioxide gas in a person's breath, revealing respiratory diseases in children and adults, and allowing anesthesiologists to monitor a patient's breathing during surgery.
In the field, emergency responders may be able to use the new sensor to verify proper breathing tube placement, monitor the patient's respiratory patterns and assess the effect of life support measures.
While the Nanomix device is already capable of monitoring human breathing in laboratory settings, the researchers are collaborating with anesthesiologists and other specialists at the University of California, San Francisco, to design and test a field-ready medical device.
The Nanomix researchers developed their nanotube transistor as part of NSF's Small Business Innovation Research program, and they are also applying the new technology to optoelectronic memory applications.
The same electronic interactions between polymers and carbon nanotubes that sense CO2 can also yield photo-sensitive devices that record the binary "on" and "off" patterns of digital memory. The memory is written optically, but read and erased electronically.
When researchers shine light on the polymer-coated nanotube transistors, electric signals are stored as charges in the nanotubes. Because different polymers absorb light differently, engineers can tune the device to work under specific light waves. By changing the voltage in the device, one can control the read and erase functions.
These research results, which were published in the September issue of Nano Letters, differ from other memory and optical applications of nanotube transistors.
Comments from the researchers:
"We are using two-layer nanodevice assembly, which allows us to control each component to change the operation of the devices. While the nanotube layer defines the density and complexity of nanodevice arrays on the chip, we can independently fine-tune the devices by using different polymers." -- Alexander Star
Comments from UCSF:
Comments from NSF:
"This is a high-risk, high-return technology. On a larger scale, the finalized product would lower the cost of respiratory tract monitoring, becoming an essential tool for intensive care units and during anesthesia." -- Winslow Sargeant
For more information on this research, see: http://www.nano.com/nr-article-081704.html.
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