Spin Polarized Chemiresistive CNT Sensors for Selective Detection of Explosive Molecules

Carbon nanotube (CNT) heterostructures have been developed to address a variety of electrical and electrochemical applications, including gas sensing. Examples include the CNT encapsulation of halogen or alkali metal dopants and the surface decoration of CNTs with ferromagnetic materials. Spin polarized chemiresistive sensing, recently proposed for graphene nanoribbon (GNR) based devices, offers a new opportunity for CNT heterostructures in gas sensing applications, one which exploits fundamental quantum physics. Ab initio computational research suggests that iron-filled CNT sensors subjected to a bias voltage and a transverse electric field offer both high sensitivity and excellent selectivity in the trace detection of explosive molecules. As compared to GNR sensors employing the same sensing mechanism, CNT heterostructures show an order of magnitude increase in sensitivity to trinitrotoluene (TNT) and the ability to discriminate between background gases, nitroaromatic explosives, and chemically similar nitramine explosives at a current threshold level a factor of 2 less stringent than that demanded by graphene sensors.