Use of Microcantilevers for the Monitoring of Molecular Binding to Self-Assembled Monolayers

Abstract

We measured the adsorption of water vapor and trinitrotoluene (TNT) on a silicon cantilever that was coated with a self-assembled monolayer (SAM) of 4-mercaptobenzoic acid on one surface. Even though hydrogen bonding is responsible for adsorption in both cases, the adsorption characteristics were quite different for the two species. In the case of water vapor, the mass loading and bending both increased with relative humidity in a linear fashion. For TNT in the dry nitrogen carrier, the mass loading and bending initially increased rapidly and then leveled off around one monolayer of coverage irrespective of the TNT concentration. This study shows that microcantilevers provide a convenient and versatile platform for the monitoring of molecular binding to SAMs. LA034969N

Approaches to Increasing Surface Stress for Improving Signal-to-Noise Ratio of Microcantilever Sensors

“…29,30,31 Other examples include the interaction of Ca 2+ with OH - and NH 2 species on the Si 3 N 4 surface (0.46 N/m of surface stress), 32 the conversion of SiOH to SiO - or SiOH + ,33 an interaction of the surface charges with Na + ions in a salt solution,34 hydrogen bonding between water vapor and 4-mercaptobenzoic acid (3.2 N/m of surface stress),35 the interaction of the same coating with trinitrobenzene (0.76 N/m of surface stress), and the of HS(CH 2 ) 2 COOH with protons or OH - (3.0 N/m of surface stress) 36…”

Swelling signals of polymer films measured by a combination of micromechanical cantilever sensor and surface plasmon resonance spectroscopy

“…The swelling of a thin polymer film results in a static bending of the MCS (static mode), which can be measured by various optical techniques [11,12] or microelectronic principles [9,13,14]. The bending depends on the concentration of the solvent in which the MCS is situated [15]. Even molecular monolayers can be used as functional MCS coatings [16].…”

Mass Metrology

“…The tapping mode has been successfully demonstrated in both air and liquid environments [97]. These are so-called contact techniques, where the probe tip was dragged over the surface, hence producing the micro-cantilever detection.…”