The microcantilever beam (Figure 1) is one of the simplest MEMS components, derived from the atomic force microscopy (AFM) probe, which was originally used for the detection of small forces, and is now widely used in AFM, accelerometers, and biochemical sensors. In 1968, Wilfinger et al. [1] used a large-volume silicon-based cantilever beam (50mm *30mm *8mm) as a sensor to study the adsorption-induced microbeam bending and resonance frequency changes caused by different temperatures. In 1979, Petersen et al. [2] developed a microcantilever-type micromechanical film to study its switching properties. In 1983, Kolesar et al. [3] constructed an electronic detection system using microcantilever beams for the detection of nerve agents. In 1985, Binnig and Quate developed the first atomic force microscope based on the scanning tunneling microscope. Atomic force microscopy is not only capable of imaging the microscopic surface of molecules, but also for manipulating molecules or measuring forces between individual molecules [4]. The advent of atomic force microscopy laid the foundation for microcantilever sensing methods.
With the gradual maturity of the manufacturing process of atomic force microscopes, there are more and more reports of microcantilever beams as sensors. So far, micro-cantilever sensing technology, as an emerging sensing technology, is still one of the hot areas of research. Further improving the sensitivity of the detection system, expanding the detection channel, reducing the cost of micro-cantilever beams, enhancing the ease of operation of the system, and expanding the scope of its practical application are the main directions of future research.
Fig.1. SEM diagrams of micro-cantilever beams of different shapes and their arrays.
When there is molecular adsorption or molecular recognition on the surface of the microcantilever beam, it can cause the cantilever to bend deformation or resonance frequency shift. Combined with different signal readout methods (optical or electrical), the microcantilever sensor monitors the changes of these two physical quantities through two different operating modes, namely: static and dynamic.
References: 1] Wilfinger R J, Bardell P H, Chhabra D S, et al the resonistor: a frequency selective device utilizing the mechanical resonance of a silicon substrate[j]. ibm j res dev, 1968, 12:113-118.
2] petersen k e, micromechanical membrane switches on silicon[j]. ibm j res dev, 1979, 23:376-385.
3] kolesar e s, electronic nerve agent detector[p].1983,4,549,427, september 19.
4] binnig g, quate c f, gerber c, atomic force microscopy[j]. phys rev lett 1986, 56:930-933.
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