title: Dual-gate polysilicon nanoribbon biosensors enable high sensitivity detection of proteins.
abstract: We demonstrate the advantages of dual-gate polysilicon nanoribbon biosensors with a comprehensive evaluation of different measurement schemes for pH and protein sensing. In particular, we compare the detection of voltage and current changes when top- and bottom-gate bias is applied. Measurements of pH show that a large voltage shift of 491 mV pH(-1) is obtained in the subthreshold region when the top-gate is kept at a fixed potential and the bottom-gate is varied (voltage sweep). This is an improvement of 16 times over the 30 mV pH(-1) measured using a top-gate sweep with the bottom-gate at a fixed potential. A similar large voltage shift of 175 mV is obtained when the protein avidin is sensed using a bottom-gate sweep. This is an improvement of 20 times compared with the 8.8 mV achieved from a top-gate sweep. Current measurements using bottom-gate sweeps do not deliver the same signal amplification as when using bottom-gate sweeps to measure voltage shifts. Thus, for detecting a small signal change on protein binding, it is advantageous to employ a double-gate transistor and to measure a voltage shift using a bottom-gate sweep. For top-gate sweeps, the use of a dual-gate transistor enables the current sensitivity to be enhanced by applying a negative bias to the bottom-gate to reduce the carrier concentration in the nanoribbon. For pH measurements, the current sensitivity increases from 65% to 149% and for avidin sensing it increases from 1.4% to 2.5%.
authors.affiliation: Zepler Institute, Electronics & Computer Science, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: I
authors.initials: I
authors.lastname: Zeimpekis
authors.forename: K
authors.initials: K
authors.lastname: Sun
authors.forename: C
authors.initials: C
authors.lastname: Hu
authors.forename: N M J
authors.initials: NM
authors.lastname: Ditshego
authors.forename: O
authors.initials: O
authors.lastname: Thomas
authors.forename: M R R
authors.initials: MR
authors.lastname: de Planque
authors.forename: H M H
authors.initials: HM
authors.lastname: Chong
authors.forename: H
authors.initials: H
authors.lastname: Morgan
authors.forename: P
authors.initials: P
authors.lastname: Ashburn
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011485:Protein Binding; D011506:Proteins / Q000032:analysis*; D012825:Silicon / Q000737:chemistry*; D014173:Transistors, Electronic
chemical_list: D037742:Nanotubes, Carbon; D011506:Proteins; D012825:Silicon