In nature, unidirectional fluid flows are often induced at micro-scales by cilia and related organelles. A controllable unidirectional flow is beneficial at these scales for a range of novel robotic and medical applications, whether the flow is used for propulsion (e.g. swimming robots) or mass transfer (e.g. prosthetic trachea). Ionic Polymer Metal Composites (IPMCs) are innovative smart materials that can be used directly as active propulsive surfaces rather than a traditional motor and propeller. IPMC actuators with two segmented electrodes that attempt to mimic the motion of cilia-like organelles have been realized. In this paper the optimization of these actuators towards producing unidirectional flows is described. A parametric study of the kinematic and hydrodynamic effect of modulating the drive signal has been conducted. As with eukaryotic cilia and flagella found in mammals, the segmented IPMC actuator can generate both flexural (asymmetric) and undulatory (symmetric) motions from the same physical structure. The motion is controlled by applying profiles of driving frequencies and phase differences. Kinematic analysis using a camera and laser displacement sensor has been used to measure and classify different motion types. The hydrodynamic forces produced by each motion type have been estimated using particle-tracking flow visualization. This allows drive signal profiles to be ranked in terms of fluid flow momentum transfer and directionality. Using the results of the parametric study, the IPMC motion is optimized towards producing unidirectional flow via repeatable cilia-inspired motion.

Date Published: 9 April 2010
PDF: 11 pages
Proc. SPIE 7642, Electroactive Polymer Actuators and Devices (EAPAD) 2010, 76421S (9 April 2010); doi: 10.1117/12.847552

Published in SPIE Proceedings Vol. 7642:
Electroactive Polymer Actuators and Devices (EAPAD) 2010
Yoseph Bar-Cohen, Editor(s)