A microcantilever-based alcohol vapor sensor-application and response model

Abstract

A recently developed microcantilever probe with integrated piezoresistive readout has been applied as a gas sensor. Resistors, sensitive to stress changes, are integrated on the flexible cantilevers. This makes it possible to monitor the cantilever deflection electrically and with an integrated reference cantilever background noise is subtracted directly in the measurement. A polymer coated cantilever has been exposed to vapors of various alcohols and the resulting cantilever response has been interpreted using a simple evaporation model. The model indicates that the cantilever response is a direct measure of the molecular concentration of alcohol vapor. On the basis of the model the detection limit of this cantilever-based sensor is determined to be below 10 ppm for alcohol vapor measurements. Furthermore, the time response of the cantilever can be used to distinguish between different alcohols due to a difference in the evaporation rates.

Special cantilever geometry for the access of higher oscillation modes in atomic force microscopy

“…The most widespread application is likely the cantilever as a supporting structure for the tip of an atomic force microscope ͑AFM͒, as first presented in 1986. 1 Other applications are in mass sensors, 2 as a sensor for gases and biomolecules, 3 or as the recently developed artificial nose 4 and millipede. 5 Many of the molecular detection devices are based on static cantilever bending due to the development of a surface stress as a result of the interaction between the molecules of interest.…”

Integrated MEMS/NEMS Resonant Cantilevers for Ultrasensitive Biological Detection

“…For example, piezoresistive read out based on measuring the bending stress of the cantilever is a suitable approach [17][18][19]. Using the piezoresistive cantilevers, chemical vapors have been detected with high sensitivity [20][21][22]. It is worth to point out that these previously developed piezoresistive microcantilevers, more often than not, comprised polysilicon piezoresistors in silicon nitride cantilever or doped singlecrystalline silicon piezoresistors in silicon cantilever.…”

Piezoresistive effect in top-down fabricated silicon nanowires

“…This increase in the piezoresistive effect is of great importance in the field of highly sensitive devices, e.g. cantilever based sensing for biomedical applications [2].…”