Cantilever Sensors: Nanomechanical Tools for Diagnostics

Abstract

Cantilever sensors have attracted considerable attention over the last decade because of their potential as a highly sensitive sensor platform for high throughput and multiplexed detection of proteins and nucleic acids. A micromachined cantilever platform integrates nanoscale science and microfabrication technology for the label-free detection of biological molecules, allowing miniaturization. Molecular adsorption, when restricted to a single side of a deformable cantilever beam, results in measurable bending of the cantilever. This nanoscale deflection is caused by a variation in the cantilever surface stress due to biomolecular interactions and can be measured by optical or electrical means, thereby reporting on the presence of biomolecules. Biological specificity in detection is typically achieved by immobilizing selective receptors or probe molecules on one side of the cantilever using surface functionalization processes. When target molecules are injected into the fluid bathing the cantilever, the cantilever bends as a function of the number of molecules bound to the probe molecules on its surface. Mass-produced, miniature silicon and silicon nitride microcantilever arrays offer a clear path to the development of miniature sensors with unprecedented sensitivity for biodetection applications, such as toxin detection, DNA hybridization, and selective detection of pathogens through immunological techniques. This article discusses applications of cantilever sensors in cancer diagnosis.

Nanomechanical resonators and their applications in biological/chemical detection: Nanomechanics principles

“…Unlike molecular recognition, which uses labeling, MEMS/NEMS devices have enabled the fast, reliable, label-free detection of specific molecules related to specific diseases, which implies their tremendous potential in performing early diagnosis of specific diseases such as cancer [37,38,42,[127][128][129][130][131][132][133]. The detection principle is the direct transduction of molecular binding on the device surface into a change of the device's physical properties such as its electrical signal [130][131][132], mechanical bending deflection and/or mechanical resonance [37,38,127]. For instance, molecular detection using microcantilever is attributed to the measurement of bending deflection change induced by surface stress that originates from molecular binding on the cantilever surface [64,134,135].…”

“…So far, many research works on the label-free detection of marker proteins using the bending deflection of cantilevers have been thoroughly reviewed in the literature [38,127,162,163]. The detection scheme based upon bending deflection change has the significant drawback such that it does not enable sensing the marker proteins in very low concentration < ~1 ng/ml.…”

Unconventional uses of microcantilevers as chemical sensors in gas and liquid media

“…In recent years, interest in microcantilever-based chemical and bio-chemical sensing systems has risen due to their projected high sensitivity [1], [2], [3], [4] and [5]. The large ratio of surface area to accessed by following the link in the citation at the bottom of the page.…”

A 16-microcantilever array sensing system for the rapid and simultaneous detection of analyte

“…As a result, microcantilever sensors have been successfully applied in many proof-ofpurpose applications including cancer detection [3], detecting the human immunodeficiency virus (HIV) [4,5], drug development [6], monitoring changes in pH [7], detecting gases from explosives [8], DNA hybridization [9], and studying antigen-antibody interactions [10].…”