Theory of microstructured polymer–electrolyte artificial muscles

Abstract

Ionic electroactuator beams are promising systems for artificial muscles in micro/nanorobotics. Here a theory is developed to investigate one promising class of such systems, which employs flexible volume-filling electrodes impregnated with polymer electrolyte. The theory provides analytical formulae for the equilibrium beam curvature as a function of voltage and structure-related operational parameters. It predicts a possible enhancement of beam curvature by orders of magnitude over that of flat electrodes. Volume-filling electrodes thus constitute one of the 'strongest' architectures for voltage-induced movement. Approximate expressions for the dynamics of tandem pore charging and beam deflection are developed to determine the maximum pore length that still warrants a sufficiently fast response time (up to 1 s). Upper bounds on applied voltage and response time constrain the maximal device thickness and curvature, and therefore, the resulting work such device can perform.

Electrochemical metamaterials

“…One class of such materials which is particularly smart are polymer electrolyte electroactuators for robotics [7], reverse actuators such as harvesters of electricity from walking or any other mechanical motion (see e.g. references on piezo [8,9], capacitive [10][11][12] and nanotribological [13,14] devices, and the literature cited there).…”

Electrotunable friction with ionic liquid lubricants

“…Switching the field can modify the composition and/or arrangement of these ions and therefore the overall friction characteristics of the filmsee Box 1. Voltage-control through rearrangement of ions between chargeable surfaces has been widely used in polymer-electrolyte based electroactuators 46 or electrowetting 47 . In EF, we deal with 'electroactuation' on the molecular level using 'electroactive lubricants', where depending on how one polarizes the electrodes, both the nanofilm thickness, the distribution of ions (including the ratio of anions and cations), or even the phase behavior and relaxation timescale of the film can be changed.…”