Study of microcapillary pipette-assisted method to prepare polyethylene glycol-coated microcantilever sensors

Microcantilever sensors were prepared by direct deposition of polyethylene glycol (PEG) onto the microcantilever surfaces using a microcapillary pipette. The physical properties of the PEG coatings: mass, surface area, volume and thickness were studied. The sensors were tested by exposing them to trace ethanol vapor and the physical properties of the micropipette-deposited PEG coatings were correlated with sensor response. Most of the PEG-coated microcantilevers demonstrated reproducible bending signals upon repeated exposure to ethanol (EtOH) vapor. Evident in the study is that uniformity in the gross morphology and surface structure of the PEG coating was not required for good sensor response. However, the location of the PEG on the microcantilever, PEG film thickness and surface area contributed to optimum response to exposure to EtOH vapor. The results demonstrate the utility of direct application of coatings onto microcantilevers by the micropipette technique. This method of coating microcantilevers is particularly appealing when quick, repeated tests of coated microcantilever sensors are desired as an alternative to more complex and time-consuming coating techniques.