Atomic force microscope microcantilevers used as sensors for monitoring humidity

• Develop a microcantilever sensor functionalized with PANI by spin-coating technique.
• The functionalization with sensitive layer and your use as humidity sensor.
• Change in surface tension resulting in a reversible nanomechanical bending.
• High possibility of using the device developed as a humidity microcantilever sensor.
• The hysteresis of microcantilever the sensor was lower than 2% at 10 and 20 °C.

A microcantilever sensor is presented. Functionalization of the cantilever with a polyaniline (PANI) sensitive layer and its use as a humidity sensor were investigated. Polyaniline was produced by interfacial synthesis and the sensitive layer was deposited on the microcantilever surface by the spin-coating method. The microcantilever deflection at various levels of relative humidity (RH) was read by means of the optical lever of an atomic force microscope (AFM Veeco Dimension V). A range of RH from 20% to 70% was introduced into the AFM chamber by mixing streams of dry and wet nitrogen. The sensitivity and reversibility of the sensors were assessed at various RH and temperatures (10, 20 and 30 °C). A large deflection was observed in the coated microcantilever sensors, with faster response time at 10 °C and better sensitivity and reversibility at 30 °C. These results demonstrate that the spin-coated microcantilever can be used as a sensor to detect relative humidity at various different temperatures.

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