title: Debye screening in single-molecule carbon nanotube field-effect sensors.
abstract: Point-functionalized carbon nanotube field-effect transistors can serve as highly sensitive detectors for biomolecules. With a probe molecule covalently bound to a defect in the nanotube sidewall, two-level random telegraph noise (RTN) in the conductance of the device is observed as a result of a charged target biomolecule binding and unbinding at the defect site. Charge in proximity to the defect modulates the potential (and transmission) of the conductance-limiting barrier created by the defect. In this Letter, we study how these single-molecule electronic sensors are affected by ionic screening. Both charge in proximity to the defect site and buffer concentration are found to affect RTN amplitude in a manner that follows from simple Debye length considerations. RTN amplitude is also dependent on the potential of the electrolyte gate as applied to the reference electrode; at high enough gate potentials, the target DNA is completely repelled and RTN is suppressed.
authors.affiliation: Department of Electrical Engineering, Columbia University, New York, New York 10027, United States. sfs2102@columbia.edu
authors.forename: Sebastian
authors.initials: S
authors.lastname: Sorgenfrei
authors.forename: Chien-Yang
authors.initials: CY
authors.lastname: Chiu
authors.forename: Matthew
authors.initials: M
authors.lastname: Johnston
authors.forename: Colin
authors.initials: C
authors.lastname: Nuckolls
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Shepard
mesh_terms: D015374:Biosensing Techniques; D002021:Buffers; D004247:DNA / Q000737:chemistry; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004553:Electric Conductivity; D007477:Ions; D044085:Microfluidics; D015233:Models, Statistical; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009841:Oligonucleotides / Q000737:chemistry; D055672:Static Electricity
chemical_list: D002021:Buffers; D004129:Dimethylpolysiloxanes; D007477:Ions; D037742:Nanotubes, Carbon; D009841:Oligonucleotides; C013830:baysilon; D004247:DNA