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Actualizing fast conducting polymer actuators : design optimization, fabrication, and encapsulation Ebrahimi Takalloo, Saeedeh

Abstract

Conducting polymer actuators offer large strain (> 1%) and high work density, operate at low voltages and can resonate at tens to hundreds of Hertz. Unfortunately, they dry out in air if a solvent-based electrolyte is used, and exchange ions in wet environments, both of which cause their performance to change over time. They also lack a scalable fabrication process through which devices with reproducible performance (especially with fast actuation) are achieved. In this work, we show that a 100 µm poly(styrene-b-isobutylene-b-styrene) encapsulation helps these devices to retain 80% of their stored solvent more than 1000 times longer compared to when there is no encapsulation. The shelf life of the encapsulated device, which is around 4 days when there is no encapsulation, is expected to improve by 600 times with encapsulation. We also developed a new, easily reproducible, and scalable fabrication process through which conducting polymer films as thin as 400 nm can be obtained. High electronic and ionic conductivities of 4 × 10^4 S/m and 4 × 10^-3 S/m, volumetric capacitance of 2.4 × 10^7 F/m3, and strain difference of ~0.65 %, were obtained from thin sprayed films of poly(2,3-dihydro-thieno-1,4-dioxin)-poly(styrene-sulfonate) on porous polyvinylidene fluoride membranes with thicknesses of ~3.5 µm. Using this technique, we showed that 10 mm long, 2 mm wide and 0.125 mm thick trilayers with a steady state peak to peak displacement of ~4.5 mm, and cut off frequency of ~2 Hz, produce a ~0.5 mm displacement up to 50 Hz. In this work, we also modified the already developed 2D transmission line model of trilayer conducting polymer actuators to take into account the effect of contact electrodes and the non-uniform charge-induced strain throughout the volume of the conducting polymer layers. Based on this model, we created a web-based graphical user-interface tool, named ActuaTool, to facilitate the design and modeling of trilayer conducting polymer actuators. This work is paving the way to employ fast conducting polymer actuators in real applications through developing a new fabrication process, their encapsulation and creating a design optimization tool.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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