AVS 49th International Symposium
    Applied Surface Science Tuesday Sessions
       Session AS-TuM

Paper AS-TuM9
A Novel Micromechanical Platform to Measure the Surface Stress Produced by Electroactive Polymers

Tuesday, November 5, 2002, 11:00 am, Room C-106

Session: Polymer Characterization
Presenter: V. Tabard-Cossa, McGill University, Canada
Authors: V. Tabard-Cossa, McGill University, Canada
M. Godin, McGill University, Canada
O. Laroche, McGill University, Canada
B. Seivewright, McGill University, Canada
A. Badia, Universite de Montreal, Canada
B. Lennox, McGill University, Canada
P. Grutter, McGill University, Canada
Correspondent: Click to Email
A novel platform to measure the surface stress produced by ionic electroactive polymer (EAP) materials is presented. In order for these materials to be used as conventional microactuators, it is important to accurately characterize them and, in particular, quantify the surface stress associated with the applied potential, so that their mechanical limitations and advantages can be determined. Micromechanical cantilever-based sensors, with their high sensitivity and fast response, are ideal tools for the characterization of these molecular scale electromechanical actuators. A standard, three-probe, electrochemical system is used, with an Ag/AgCl reference electrode and a Pt counter electrode, in a combined apparatus with a surface stress AFM cantilever-based sensor, where the cantilever simultaneously serves as the working electrode to obtain surface stress data in parallel with cyclic voltammetry (CV). The instrument, capable of integrating the electrochemical setup with the surface stress sensor requirements, will be described. The experimental setup, with the optimal cell geometry, necessary electronics and required software and hardware components will be shown. Dodecyl benzenesulfonate-doped polypyrrole (PPy(DBS)) in an aqueous solution of Na(DBS) is the EAP studied. Potentiostatic growth results of polypyrrole films on gold coated AFM cantilevers and their characterization by cyclic voltammetry and AFM/SEM will be presented. In addition, bending of the PPy/Au coated cantilever bilayer structure is measured as a function of applied potential. The equation used to calculate the surface stress induced during cyclic voltammograms circumvents the need to know the cantilever's Young's modulus by using readily measurable cantilever properties.@footnote 1@ Finally, surface stress as a function of applied potential will be shown and its correlation with oxidation and reduction peaks addressed. @FootnoteText@ @footnote 1@M. Godin et al., Appl. Phys. Lett. 79, 4 (2001).