Every breath you take

Researchers at Nanomix in Emeryville, California have created a transistor that fuses carbon nanotubes, polymers and silicon into a human breathing monitor dubbed the capnography sensor.

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.

US National Science Foundation (NSF) supported researchers at Nanomix in Emeryville, California, have created a transistor that fuses carbon nanotubes, polymers and silicon into a human breathing monitor called a capnography sensor.

Alexander Star and his colleagues at Nanomix and the University of California, Los Angeles, describe the new sensor in 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 anaesthesiologists 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 anaesthesiologists 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 photosensitive 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.

“This is a high-risk, high-return technology,” commented Winslow Sargeant, NSF Small Business Innovation Research Program officer. “On a larger scale, the finalised product would lower the cost of respiratory track monitoring, becoming an essential tool for intensive care units and during anaesthesia.”