Abstract
While increasing power output is the most straight-forward solution for faster and stronger motion in technology, sports, or elsewhere, efficiency is what separates the best from the rest. In nature, where the possibilities of power increase are limited, efficiency of motion is particularly important; the same principle can be applied to the emerging biomimetic and bio-interacting technologies. In this work, by applying hints from nature, we consider possible approaches of increasing the efficiency of motion through liquid medium of bilayer ionic electroactive polymer actuations, focusing on the reduction of friction by means of surface tension and hydrophobicity. Conducting polyethylene terephthalate (PET) bilayers were chosen as the model actuator system. The actuation medium consisted of aqueous solutions containing tetramethylammonium chloride and sodium dodecylbenzenesulfonate in different ratios. The roles of ion concentrations and the surface tension are discussed. Hydrophobicity of the PET support layer was further tuned by adding a spin-coated silicone layer to it. As expected, both approaches increased the displacement—the best results having been obtained by combining both, nearly doubling the bending displacement. The simple approaches for greatly increasing actuation motion efficiency can be used in any actuator system operating in a liquid medium.
Highlights
Soft, compliant ionic electroactive polymer actuators are expected to find applications in many fields, from micro machining [1] for valves and pumps [2,3], simultaneous sensors and actuators [4], lab on chip devices [5], smart textiles [6], and soft robotics [7] to biomedical devices [8]
Nature has introduced a large variety of techniques for ensuring optimal surface interactions; hydrophobic surfaces are made use of by representatives of both fauna and flora [16]; the Nepenthes pitcher plants are a well-known example of applying lubrication to already slippery surfaces to effectively catch insects [17]
We describe approaches to increasing the efficiency of soft ionic electroactive polymer actuators in aqueous electrolyte solutions using a simple polyethylene terephthalate (PET) –polypyrrole (PPy) bending double layer as the model system
Summary
Compliant ionic electroactive polymer actuators are expected to find applications in many fields, from micro machining [1] for valves and pumps [2,3], simultaneous sensors and actuators [4], lab on chip devices [5], smart textiles [6], and soft robotics [7] to biomedical devices [8]. It is perhaps somewhat surprising that the growing understanding of friction, in particular, that of water-based and charged systems [19], has not been applied in the context of soft actuator motion in electrolyte solutions; as with miniaturization, the efficiency and surface interactions become critical. We describe approaches to increasing the efficiency of soft ionic electroactive polymer actuators in aqueous electrolyte solutions using a simple polyethylene terephthalate (PET) –polypyrrole (PPy) bending double layer as the model system. As a PET-PPy/DBS bilayer bends in an aqueous electrolyte, it has to apply force against the water resistance, consuming energy, which results in suppressed displacement of the bilayer. Our goal in this work was to see if it is possible to minimize the liquid media resistance to bending of the actuator by increasing the actuator hydrophobicity via applying a backside coating of polydimethylsiloxane (PDMS). Hydrophobic PDMS surfaces have been applied in microchannels [34] to increase the flow in microfluidics [35] devices, as the Milli-Q water-PDMS interface has a rather low contact angle, in the range of 100–110 degrees [36]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
