Nanotubes keep tabs on breathing
Tiny technology could monitor patients' vital signs.
A nanotechnology device that can gauge the levels of carbon dioxide in a puff of air could help medical workers to check patients' breathing at the scene of an accident.
Changing levels of carbon dioxide in the breath show that a patient is running into respiratory trouble and may need emergency intervention. In hospitals, doctors have sophisticated machinery to measure this vital sign, but emergency workers need smaller, portable equipment to use on the spot.
To tackle this problem, Alexander Star of the technology company Nanomix in Emeryville, California, and his colleagues turned to carbon nanotubes. These are tiny, hollow tubes of carbon that conduct electricity and can be used as electronic circuit components called transistors.
The team fused carbon nanotubes with custom-made polymers that detect carbon dioxide. When the polymers react with carbon dioxide, their electrical charge is altered and this in turn creates a measurable voltage change in the attached nanotubes. This is detected with an electronic sensor.
According to the study, published in Advanced Materials1, a 10% rise in carbon dioxide levels altered the electrical conductance of the carbon nanotubes by a fifth. The scientists went on to show that the transistor's conductivity changed in parallel with the levels of the gas.
With promising results in the lab, the group now plans to work with doctors to develop a device that could be used in the field.
Nanotechnology is likely to lead to numerous medical applications in the future, predicts Ottilia Saxl at the Institute of Nanotechnology in Stirling, UK, such as ways to detect other molecules inside or outside the body. "When you've got one sensor using carbon nanotubes, you've just got to think of the endless possibilities."
- Star A., et al. Advanced Materials, published online at doi:10.1002/adma.200400322 (2004).