Single-Walled Carbon Nanotube Thin-Film Sensor for Ultrasensitive Gas Detection

Abstract

We demonstrated a gas sensor fabricated by growing a single-walled carbon nanotube (SWNT) thin film directly on a conventional sensor substrate. NO2 and Cl2 were detected down to the ppb level under room-temperature operation with a fast response. Using an electrical breakdown technique, gas response sensitivity was improved by an order of magnitude. The relationship between gas concentration and sensor response was derived based on the Langmuir adsorption isotherm, predicting a detection limit of 8 ppb for NO2. The SWNT thin-film gas sensor exhibits merits over other types of sensors by virtue of its simplicity in fabrication and feasible application.

Cobalt Nano Particle Size Dependence of Noise Modulations in Relation to Nonlinearity

“…Many applications have been proposed such as nano-size transistors, bio sensors, and interconnections in large-scale circuits. Several technologies can be utilized in these applications, such as high-sensitive gas sensors [3], label-free detection for bio molecules [4,5], and n-type field effect transistor (FET) fabrication [6,7]. The room temperature operation of single electron transistors, which can usually work only at low temperature, can be archived through the use of nanotechnology [8,9].…”

Theoretical Studies of Substitutionally Doped Single-Walled Nanotubes

“…Over the past 20 years, research efforts have aimed to improve both efficiency and selectivity of nanotube synthesis, as well as understand their chemical reactivity and extraordinary electronic and thermal properties [3][4][5]. Carbon nanotubes have significant potential for application in molecular electronics [6][7][8][9][10][11][12][13][14][15], nanomechanics [16][17][18][19][20], optics [21][22][23][24], sensors [6,[25][26][27][28][29][30][31], and even catalysis [32].…”

Adsorption-Based Model for Single-Wall Carbon Nanotube Response to NO2 Gas

“…The values of the correlation coefficient R 2 confirm the validity of the Freundlich isotherm at all tested temperatures. Wongwiriyapan et al (2005) presented a model that predicts the static response of the SWNT sensor. However, the latter model is valid only at low NO 2 concentrations up to 100 ppb.…”

“…There is experimental evidence that the steady-state response depends strongly on the adsorption of gas molecules onto the active sites distributed in the sensing material. Previous work suggests that the latter gas adsorption could follow a simple, reversible Freundlich isotherm (Clifford and Tuma 1983a;Llobet 2001) or Langmuir isotherm (Wongwiriyapan et al 2005). In our model, the static response was best described by the Freundlich adsorption isotherm either when the gas concentration or the operating temperature was varied.…”