CNT-FET gas sensor using a functionalized ionic liquid as gate

We propose a gas sensor using combination of carbon nanotubes (CNTs) and ionic liquid (IL). In our research, we used IL, 1-ethyl-3-methyl imidazolium tetrafluoroborate ([EMIM][BF
₄
]) which specially absorbs CO
₂
/NH
₃
, and polymer, polyethyleneimine (PEI) which absorbs CO
₂
. This IL or the mixture of IL and PEI dropped on the CNT-FET were applied as a CNT-FET IL-gate and a surface modification material of CNTs. When the IL absorbs specific gases, the ion types and concentrations change. We measured the change of CNT I-V property by applying a voltage to the IL-gate to attract the ions onto the CNT surface.