A preliminary study of conducting polymers as microvalve seals

We report here on the first investigation into the behaviour of conducting polymers as seals for microvalves. Poly(pyrrole) is known to be reasonably stable in air and is also one of the easiest conducting polymers to synthesise either by chemical or electrochemical polymerisation. It is known to offer interesting tribological properties and so is chosen as the exemplar material here. Poly(pyrrole) with three dopants, namely 1-decanesulfonate (DSA), methylphosphonate (MPA) and 1-butanesulfonate (BSA) films were deposited electrochemically with a thickness between 0.5 and 1.5 μm, on gold electrodes patterned on Si-wafer (4×4 mm). Test results show that the leakage rate for the PPY films can be down to 0.5 cm3 min−1. The PPY films doped with MPA have the best performance. The effects of the choice of the electrochemical deposition conditions and resulting morphology, the film thickness and the choice of counter-ions on the leakage rate are also discussed.