Timothy Swager, Ph.D.
Massachusetts Institute of Technology
NIEHS grantees recently developed a sensitive, inexpensive sensor that uses carbon nanotubes to measure airborne N-nitrosamines in real time. N-nitrosamines are toxic by-products formed during manufacturing and food processing and have been found in air, water, and food. Before the development of this tool, detecting N-nitrosamines was a long, expensive, and technically challenging process.
The researchers developed the sensor, evaluated its performance, and explored different parameters to optimize the device for detecting relevant levels of N-nitrosamines, including N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), and N-nitrosodibutylamine (NDBA).
The final product consisted of functionalized cobalt (III) tetraphenylporphyrin molecules deposited onto single-walled carbon nanotubes. The carbon nanotubes were stretched between gold electrodes, which conducted current through the nanotubes. The cobalt (III) tetraphenylporphyrin molecules selectively bound to N-nitrosamine compounds in air, which resulted in a change in electrical resistance across the electrodes. Researchers can measure the change to determine the concentration of N-nitrosamines.
The researchers demonstrated that the small, portable sensors could detect concentrations of NDMA, NDEA, and NDBA as low as 1 part per billion without background interference. They also showed that the sensor could be integrated with a commercial sensing chip device so results can be monitored remotely using a computer or smartphone.
Citation: He M, Croy RG, Essigmann JM, Swager TM. 2019. Chemiresistive carbon nanotube sensors for N-nitrosodialkylamines. ACS Sens 4(10):2819–2824.