Microcantilever

A microcantilever is a small, beam-shaped cantilever used in microelectromechanical systems (MEMS) and nanoscale sensing. It consists of a single, flexible lever anchored at one end and free at the other, enabling it to deflect under applied forces. Typical dimensions are in the tens to hundreds of micrometers in length, a few to several tens of micrometers in width, and sub-micron to a few-micrometer thickness. Fabrication is usually achieved with MEMS processes, including surface micromachining and bulk micromachining, often using silicon, silicon nitride, or other compatible materials.

Materials and coatings are chosen to tailor stiffness, durability, and surface chemistry. Silicon and silicon nitride are common due to high Young’s moduli and well-developed fabrication, while coatings can provide chemical functionalization for sensing or protective layers.

Operation modes include static and dynamic. In static mode, external forces such as adhesion, capillary, electrostatic, magnetic, or chemical interactions cause bending of the cantilever, which can be measured by optical, electrical, or piezoresistive readout. In dynamic mode, the cantilever is driven near its resonant frequency; changes in resonance frequency or oscillation amplitude reflect mass loading, stiffness changes, or surface interactions.

Key performance metrics are stiffness (spring constant), resonance frequency, quality factor, and noise. The force sensitivity scales with k and the readout method, while the resonance frequency depends on k and the effective mass. Applications range from atomic force microscopy for surface imaging to chemical and biological sensing, mass sensing, and various MEMS sensors. Challenges include stiction, drift, and environmental damping, especially in liquids.