Calculation of fluctuations in boundary layers of nanowire field-effect biosensors

Clemens Heitzinger, Yang Liu, Norbert J. Mauser, Christian Ringhofer, Robert W. Dutton

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Fluctuations in the biofunctionalized boundary layers of nanowire field-effect biosensors are investigated by using the stochastic linearized Poisson-Boltzmann equation. The noise and fluctuations considered here are due to the Brownian motion of the biomolecules in the boundary layer, i.e., the various orientations of the molecules with respect to the surface are associated with their probabilities. The probabilities of the orientations are calculated using their free energy. The fluctuations in the charge distribution give rise to fluctuations in the electrostatic potential and hence in the current through the semiconductor transducer of the sensor, both of which are calculated. A homogenization result for the variance and covariance of the electrostatic potential is presented. In the numerical simulations, a cross section of a silicon nanowire on a flat surface including electrode and back-gate contacts is considered. The biofunctionalized boundary layer contains single-stranded or double-stranded DNA oligomers, and varying values of the surface charge, of the oligomer length, and of the electrolyte ionic strength are investigated.

Original languageEnglish (US)
Pages (from-to)2574-2580
Number of pages7
JournalJournal of Computational and Theoretical Nanoscience
Issue number12
StatePublished - Dec 2010


  • Field-effect biosensor
  • Fluctuation
  • Homogenization
  • Multiscale problem
  • Nanowire
  • Noise
  • Stochastic Poisson-Boltzmann equation

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Computational Mathematics
  • Electrical and Electronic Engineering


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