Highly Selective Environmental Nanosensors Based on Anomalous Response of Carbon Nanotube Conductance to Mercury Ions

We have developed a selective, sensitive, and fast single-walled carbon nanotube (swCNT) field effect transistor (FET) sensor for Hg 2+ ion detection. This sensor is based on the anomalous response of swCNT conductance to the exposure of Hg 2+, which provides the selectivity toward Hg 2+ over various other metal ions through a strong redox reaction between swCNTs and Hg 2+ . Our sensor system exhibited a detection limit of 10 nM for Hg 2+ in water, which is comparable with the maximum allowable limit of mercury ions in drinking water set by most government environmental protection agencies. It also has a wide measurable detection range from 10 nM to 1 mM and a sensitive quantifying range with a steep slope for Hg 2+ detection.