Integrative Graduate Education and Research Training (IGERT)

Our research group is interested in exploring the magnetic properties of these carbon nanotubes and their potential as magnetic biosensors.  Other papers have reported using carbon nanotubes in sensor applications, but not in biomagnetism. This paper will review several different research articles and scientific papers dealing with sensors and properties of carbon nanotubes.

Chopra et al. (2003) showed that carbon nanotubes can be used as selective gas sensors due to a change in the dielectric constant rather than electrical conductivity upon gas exposure.  These tubes exhibit noticeable shifts in their resonant frequency when exposed to gases such as NH₃, CO, He, Ar, N₂ and O₂.  Gas concentrations as low as 100 ppm can be detected with their sensor configuration.

Temperature nanothermometers have been constructed and tested using carbon nanotubes.  Researchers have filled the tubes with a liquid gallium column that exhibits a linear thermal expansion.  One can see how this can be a reliable nanothermometer.  Li et al. (2003) has improved upon this design by using a MgO nanotube to avoid the fact that carbon nanotubes are prone to fast degredation in air as the temperature reaches 600-700 ^oC.  This would not be a problem in biomedical thermometry when the human body temperature is near 37 ^oC.

The background research on this linear thermal expansion behavior was performed by Gao et al. (2002).  Their group investigated the melting and expansion behavior of indium confined in carbon nanotubes and found it to be quite different than at macroscopic sizes.  This analysis clarified the understanding of nanotube-based thermometry.

Several other papers have reported the properties of pore structure Cinke et al (2002), additional information dealing with gas adsorbtion in carbon nanotubes Sumanasekera et al. (2000), and thermoelectric properties of carbon nanotubes in gas detection Adu et al (2001).  A final investigation we report here looked at the hysteresis shift of Iron-filled carbon nanotubes Prados et al. (2002).  This paper discusses the interesting hysteresis loop shift indicating an interface of two different phases of Iron.  The unique magnetism found in this system may have many applications to biomagnetism and sensors.