Cantilever Sensors: Nanomechanical Tools for Diagnostics Citation

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. 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. very attractive. Biosensing technologies based on cantilever arrays have the potential of satisfying this need for multi-target detection with high sensitivity and selectivity using very small volumes of sample. Microcantilevers are micromechanical beams that are anchored at one end, such as diving spring boards, that can be readily fabricated on silicon wafers and other materials. Their typical dimensions are approximately 100 microns long, 20 microns wide, and 1 micron thick. The microcantilever sensors are physical sensors that respond to surface stress changes due to chemical or biological processes. 1 When fabricated with very small force constants, they can measure forces and stresses with extremely high sensitivity. The very small force constant (less than 0.1 N/m) of a cantilever allows detection of surface stress variation due to the adsorp-tion (or specific surface-receptor interaction) of molecules. Adsorption of molecules on one of the surfaces of the typically bimaterial cantilevers …