Gas-induced variation in the dielectric properties of carbon nanotube bundles for selective sensing

Abstract

There is an increasing demand for robust, miniaturized sensors with ppm or parts per 10 9 ͑ppb͒ sensing capability, and high selectivity to different chemical or biological species. Here we show that trace amounts ͑ppb͒ of gases or organic solvent vapors can be detected with high selectivity and sensitivity using single-walled carbon nanotube bundles in a resonator configuration. The enhanced sensing properties result from a change in the effective dielectric properties of the resonator when exposed to different gas environments. A theoretical model is described which computes resonant frequency shifts that are in remarkable agreement with corresponding experimental shifts exhibited by the resonator when exposed to different gas molecules. This work demonstrates a gas-sensing platform with superior sensitivity and selectivity for gas detection, and presents advantages in terms of portability and recovery time. In particular, the sensing platform does not require functionalized carbon nanotubes to enhance specificity, or wire connection to the nanotubes making it attractive for remote sensor technology.

n-Type gas sensing characteristics of chemically modified multi-walled carbon nanotubes and PMMA composite

“…Carbon nanotubes (CNTs) have a high surface area for the adsorption of gases, and more importantly, their conductivity and capacitance are greatly changed by the adsorbates, which make them an attractive candidate for construction of microsensors. In recent years, there have been a number of reports on CNTbased gas sensors with the advantages of high sensitivity, fast response and room temperature detection [2,[4][5][6][7][8][9][10][11][12][13]. Depending on their semiconducting properties, CNT sensors could exhibit p-or n-type response to gases, which is featured with increased or decreased resistivity in reducing gases such as ammonia and methanol [2,[5][6][7][8][9]12,13].…”

Carbon Nanotube-Based Sensors

“…Carbon Nanotube-Based Sensors [114], [115], [117], CO [137], [147], [119], [136], [137], [174], [175] [143], [152], [153] [114], [139], [150], Glucose [112], [135], [152], [163], [165], [140], [142], [176] [146], [149], [168] [160] Other chemical [116], [118], pesticides vapors [129], [130], [131], [137], [155], [157], [173] such as sensors, biosensors, and biological fuel cells and reactors. Several types of carbon nanotube sensors were reviewed in this section.…”

Multiwalled carbon nanotubes for dielectric sensing of biological systems: An effective treatment of polarization

“…The frequency shifts (Eq. (2)) have been calculated [23] for a SWNT exposed to very small amounts of molecules such as N 2 , CO, O 2 , NH 3 and CH 3 Br described as single polarizable centers, i.e. by limiting a $ m to the point molecule polarizability tensor in Eq.…”