Fundamental Mechanisms in Microcantilever Sensors

Thomas G. Thundat

Oak Ridge National Laboratory, Oak Ridge TN 37831-6123

The advent of inexpensive, mass-produced microcantilevers promises to bring about a revolution in the field of miniature chemical, physical, and biological sensor array development. Molecular adsorption results in variation in resonance frequency due to mass loading and cantilever bending due to variation in surface free energy. Depending on the nature of analyte-substrate interaction, the adsorption the stress can be bulk stress or surface stress resulting in varied responses. When surface stress is involved, cantilever materials, and physical structure determine cantilever sensitivity while surface effects and energy loss mechanisms determine sensor selectivity. Therefore, understanding the chemical and physical properties of cantilever surfaces and the fundamental process involved in energy transfer process is important optimizing the sensor sensitivity and selectivity. Examples of various surface effects will be discussed along with latest experimental results.