Aug 29, 2007
Nanotube Asthma Sensors
Single-walled carbon nanotubes (SWNTs) have been hailed for their role in molecular electronic devices. All of the atoms of these 1D structures are located on the surface. This exposes their electronic structure, which is sensitive to variations in the local charge environment. By measuring the conductance of a network of SWNTs in a field-effect transistor device, it is possible to monitor electronic variations due to the presence of a biomarker for asthma – nitric oxide.
This sensor, developed at the University of Pittsburgh, is based on the oxidation of an exhaled breath component, nitric oxide (NO), and the transduction that takes place between the gas analyte and the carbon nanotube device. By functionalizing the device with poly(ethylene imine) the researchers were able to improve sensitivity to NO to parts per billion concentrations. Furthermore, this group was able to detect this analyte gas in the presence of interfering components, such as O2 and CO2. The addition of an acidic gas scrubber before the NO oxidizer has made it possible to capture interfering components and thus detect minute concentrations of NO in simulated breath conditions.
Current techniques to monitor NO in asthmatic patients involve bulky, expensive equipment and a trip to the hospital for the outpatient procedure. With this sensor technology, it is possible to have an inexpensive, portable, reusable device that responds in real-time. This opens up the possibilities for home diagnostics in asthma treatment and monitoring, much the same as for glucose detection in diabetics.
About the author
Alexander Star is an assistant professor in the department of chemistry at the University of Pittsburgh, US. He is currently conducting research on the synthesis and characterization of nanomaterials with applications in energy and life sciences.