Effect of thickness of carbon nanotube films on enhancement of sensor response

Molecular adsorption on carbon nanotube (CNT) films follows the Langmuir adsorption isotherm even for polar molecules at low gas pressures. Therefore, this film can be applied to gas sensors. In order to clarify the effect of thickness on sensor response, we fabricated CNT films of different thicknesses and observed their behavior. Because the adsorption is expected to occur near the surface, we determined the effective penetration thickness for the gas molecules and identified an approximate thickness of 7 mu m.