title: Investigation of sensing mechanism and signal amplification in carbon nanotube based microfluidic liquid-gated transistors via pulsating gate bias.
abstract: The advent of a carbon nanotube liquid-gated transistor (LGFET) for biosensing applications allows the possibility of real-time and label-free detection of biomolecular interactions. The use of an aqueous solution as dielectric, however, has traditionally restricted the operating gate bias (VG) within |VG| < 1 V, due to the electrolysis of water. Here, we propose pulsed-gating as a facile method to extend the operation window of LGFETs to |VG| > 1 V. A comparison between simulation and experimental results reveals that at voltages in excess of 1 V, the LGFET sensing mechanism has a contribution from two factors: electrostatic gating as well as capacitance modulation. Furthermore, the large IDS drop observed in the |VG| > 1 V region indicates that pulsed-gating may be readily employed as a simple method to amplify the signal in the LGFET and pushes the detection limit down to attomolar concentration levels, an order of magnitude improvement over conventionally employed DC VG biasing.
authors.affiliation: School of Material Science & Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
authors.forename: I Putu Mahendra
authors.initials: IP
authors.lastname: Wijaya
authors.forename: Tey Ju
authors.initials: TJ
authors.lastname: Nie
authors.forename: Isabel
authors.initials: I
authors.lastname: Rodriguez
authors.forename: Subodh G
authors.initials: SG
authors.lastname: Mhaisalkar
mesh_terms: D000669:Amplifiers, Electronic; D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D011107:Polylysine / Q000032:analysis*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014173:Transistors, Electronic
chemical_list: D037742:Nanotubes, Carbon; D011107:Polylysine