DNA-Functionalized Carbon Nanotube Chemical Sensors
We have developed chemical sensors consisting of a single-walled
carbon nanotube field effect transistor (swCN-FET) with a nanoscale
layer of single stranded DNA (ssDNA) adsorbed to the tube's
outerwall. The current through the swCN-FET shows a characteristic
response to gaseous analytes. This response varies depending on the
base sequence of the adsorbed ssDNA.These sensors have been able to
detect methanol, trimethylamine, propionic acid, dimethyl
methylphosphonate (a simulant of sarin), and dinitrotoluene (a
derivative of TNT) at the ppm level. The response and recovery of
this biosensor is on the order of seconds.

Figure 1: DNA-Functionalized Carbon Nanotube Chemical Sensor
Polymer and Metal Oxide Nanowire Chemical
Sensors
The Johnson Group is also studying neural network nanogas sensor
arrays in cooperation with
Dr. Mallouk's group at Penn State. The arrays may consist of
various nanowires , e.g. PEDOT/PSS polymer nanowires, SnO2 nanowires,
etc., which are sensitive to different gases. A neural network of
these arrays can identify gases with much higher realiability. This
topic is interesting because it's a big step in realizing Artificial
Electronic NanoNoses. We electroplate on the filter membranes to
prepare the nanowires and use dielectrophoresis to assemble the
nanowires onto specific loations on the IC chip. Currently only
Yaping is working on this project in our group.

Figure 2: A single nanowire
assembled onto a 6um gap and its I-V curve

Figure 3: A single nanowire exposed
to different chemicals at different concentrations |