Surface stress of polyelectrolyte adsorption measured by micromechanical cantilever sensors

We studied the mechanical stress during the adsorption process of polyallylamine hydrochloride (PAH) and polystyrenesulfonate (PSS) polyelectrolytes using highly sensitive micromechancial cantilever sensors (MCS). Single side adsorption was achieved by functionalizing individual MCS with a 2-mercatoethylamine (2-MEA) self-assembled monolayers. Exposure of the MCS to PAH solution resulted in a constant surface stress change of 1.6±0.2 N/m between the 2-MEA functionalized and silicon sensors. We attribute the surface stress change to the formation of a stable PAH polyelectrolyte layer on top of the silicon surface. We found that a second layer consisting of PSS did not result in a negligible surface stress change.