Anomalous resonance in a nanomechanical biosensor

Amit K. Gupta, Pradeep R. Nair, Demir Akin, Michael R. Ladisch, Steve Broyles, Muhammad A. Alam, Rashid Bashir

Research output: Contribution to journalArticlepeer-review


The decrease in resonant frequency (-Δωr) of a classical cantilever provides a sensitive measure of the mass of entities attached on its surface. This elementary phenomenon has been the basis of a new class of bio-nanomechanical devices as sensing components of integrated microsystems that can perform rapid, sensitive, and selective detection of biological and biochemical entities. Based on classical analysis, there is a widespread perception that smaller sensors are more sensitive (sensitivity ≈ -0.5ωr/mC where mC is the mass of the cantilever), and this notion has motivated scaling of biosensors to nanoscale dimensions. In this work, we show that the response of a nanomechanical biosensor is far more complex than previously anticipated. Indeed, in contrast to classical microscale sensors, the resonant frequencies of the nanosensor may actually decrease or increase after attachment of protein molecules. We demonstrate theoretically and experimentally that the direction of the frequency change arises from a size-specific modification of diffusion and attachment kinetics of biomolecules on the cantilevers. This work may have broad impact on microscale and nanoscale biosensor design, especially when predicting the characteristics of bio-nanoelectromechanical sensors functionalized with biological capture molecules.

Original languageEnglish (US)
Pages (from-to)13362-13367
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number36
StatePublished - Sep 5 2006
Externally publishedYes


  • Nanocantilevers
  • Nanotechnology
  • Protein adsorption
  • Virus detection

ASJC Scopus subject areas

  • Genetics
  • General

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