A convenient approach to producing a sensitive MWCNT-based paper sensor

MWCNT/octadecylamine hybrids with interesting structures were prepared via a simple ultrasonication and drip-drying method. The morphologies of the hybrids vary from lamellae, balls, to rose-like nanoflowers, depending on the weight ratio of the two components, which could be attributed to the introduction of nanotubes into the long-chained amine with self-organization characteristics. The paper chip sensor based on MWCNT/octadecylamine hybrid shows rapid response, high sensitivity and excellent repeatability to some volatile organic compounds, especially chloroform gas. The proposed sensing mechanism of the hybrid is via the swelling of octadecylamine upon the adsorption of organic gas, thus enlarging the nanotube distance in the MWCNT/octadecylamine hybrid and leading to the conductivity decrease of the paper chip.