Pushing the Limits for Microactuators Based on Electroactive Polymers

We have previously reported on the fabrication and displacement output of electroactive polymer (EAP) microactuators less than 1 mm in length. The main limiting factor hindering their further miniaturization and their displacement output was the thickness of the commercially available polyvinylidene fluoride (PVDF) membrane used
$(\sim 110\ \mu\hbox{m})$
. In this study, we have reduced the thickness of the PVDF layer using a spin-coating technique and then electrochemically deposited polypyrrole layers on both sides of this thin film to make ultrathin-film EAP substrates with a thickness of 48
$\mu\hbox{m}$
. We then employed a laser ablation technique to fabricate microsized EAP actuators as small as 200
$\mu\hbox{m}$
in length and 50
$\mu\hbox{m}$
in width that can operate in both dry and aqueous media. This is the minimum-size EAP microactuator to be reported in the literature. Based on the operation principle of these actuators, we model them as a microcantilever beam under a uniformly distributed load. We then establish bending displacement and blocking force models to perform the following: 1) to estimate the actuation force, actuation moment, tip deflection, flexural rigidity, and strain energies per unit volume and mass for a set of microactuators as big as
$850\ \mu\hbox{m} \times 250\ \mu\hbox{m} \times 126\ \mu\hbox{m}$
and as small as
$200\ \mu\hbox{m} \times 50\ \mu\hbox{m} \times 48\ \mu\hbox{m}$
and 2) to evaluate their performance metrics.
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[2011-0250]