Roll‐to‐Roll Gravure‐Printed Carbon Nanotube‐based Transistor Arrays for a Digital Column Chromatograph

Roll-to-roll (R2R)-printed thin-film transistor-based devices have apparent advantages over their silicon-based counterparts to explore a new device concept where form factor and cost are critical. Here, the R2R gravure-printed single-walled carbon nanotube (SWCNT)-based thin-film transistor (TFT) arrays are demonstrated to show advantages in developing inexpensive digital column chromatography (DiCC). The DiCC can be easily constructed by cutting and pasting the fluoropolymer, CYTOP, coated R2R gravure-printed SWCNT-TFT arrays on the inside wall of the column. The coated CYTOP acts as an electret and induces charges depending on dipole moments of the molecules in nonpolar eluents. Since the induced charges act as an n-type dopant to the printed p-type SWCNT-TFT, the off-currents of SWCNT-TFT arrays are raised when analyte molecules with a dipole moment move to the CYTOP-coated SWCNT-TFT. By monitoring the off-current variations of the CYTOP-coated SWCNT-TFT, the flow of molecules can be digitally monitored, and even the structural isomers of molecules can be digitally differentiated in real time.