Tri-layer polymer actuators with variable dimensions

The ability of conducting polymer actuators to convert electrical energy into mechanical energy is influenced by many

factors ranging from the actuators physical dimensions to the chemical structure of the conducting polymer. In order to

utilise these actuators to their full potential, it is necessary to explore and quantify the effect of such factors on the

overall actuator performance. The aim of this study is to investigate the effect of various geometrical characteristics such

as the actuator width and thickness on the performance of tri-layer polypyrrole (PPy) actuators operating in air, as

opposed to their predecessors operating in an appropriate electrolyte. For a constant actuator length, the influence of the

actuator width is examined for a uniform thickness geometry. Following this study, the influence of a varied thickness

geometry is examined for the optimised actuator width. The performance of the actuators is quantified by examination of

the force output, tip displacement, efficiency as a function of electrical power and mechanical power, and time constant

for each actuator geometry. It was found that a width of 4mm gave the greatest overall performance without curling

along the actuator length (which occurred with widths above 4mm). This curling phenomenon increased the rigidity of

the actuator, significantly lowering the displacement for low loads. Furthermore, it was discovered that by focussing a

higher thickness of PPy material in certain regions of the actuators length, greater performances in various domains

could be achieved. The experimental results obtained set the foundation for us to synthesize PPy actuators with an

optimised geometry, allowing their performance to reach full potential for many cutting applications.