Modeling Actuation of Ionomer Cilia in Salt Solution Under an External Electric Field

Boldini, Alain; Rosen, Maxwell; Cha, Youngsu; Porfiri, Maurizio

doi:10.1115/1.4046366

Cited by 3 publications

(3 citation statements)

References 18 publications

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“…The motion of the anions is accompanied by comigrating water molecules in their hydration shell. 17,18 Due to the resulting local changes in water and anion concentration, the membrane cathode swells while its anode shrinks. Macroscopically, this differential volume change elicits a macroscopic bending motion.…”

Section: Phenomenological Description Of Solvation-driven Actuationmentioning

confidence: 99%

Experimental characterization of actuation of anion-exchange membranes in salt solution

Ulbricht

Boldini

Bae

et al. 2023

Electroactive Polymer Actuators and Devices (EAPAD) XXV

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Besides their use in separation and filtration processes, ion-exchange membranes have been adopted as electroactive polymer actuators in soft robotics and biomedical engineering, due to their unique coupling between electrochemistry and mechanics. Actuation is generated by the asymmetry in cations and anions transport, as one of the two species is bonded to the membrane backbone, whereas the other can move throughout the membrane. Typically, electrodes are plated on the membrane to enable application of an external electric field. A new, promising contactless actuation configuration for underwater applications consists of immersing a bare membrane in an electrolyte solution, between external electrodes. When an electric field is imposed across the electrodes, a macroscopic bending deformation is observed. Despite major advances in understanding the actuation of cation-exchange membranes (with fixed anions), the actuation of anion-exchange membranes (with fixed cations) is an almost untapped field. In this work, we experimentally investigate the contactless actuation of anion-exchange membranes. In the experiments, we systematically vary the anions in the external solution and inside the membrane, to unravel their effects on membrane actuation. In all tested combinations, the membrane always bends in the opposite direction compared to cation-exchange membranes. Additionally, we find a prominent influence of the external anions on the actuation strength, consistent with previous theories that attribute actuation to solvation effects. Our results help shade light on the chemoelectromechanics of anion-exchange membranes, toward their increase adoption as soft actuators.

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Section: Phenomenological Description Of Solvation-driven Actuationmentioning

confidence: 99%

Experimental characterization of actuation of anion-exchange membranes in salt solution

Ulbricht

Boldini

Bae

et al. 2023

Electroactive Polymer Actuators and Devices (EAPAD) XXV

View full text Add to dashboard Cite

show abstract

“…In fact, the pile‐up and depletion of anions is limited to thin electrical double layers in the membrane, in proximity of the membrane‐solution interface. [ 35 ] At the membrane cathode, solution anions enter the membrane, pushing counterions initially inside of the membrane into the external solution. At the membrane anode, counterions leave the membrane due to the electric field.…”

Section: Introductionmentioning

confidence: 99%

“…[31] Building on the work of Kim et al, [22] we proposed a series of experimental and theoretical endeavors to elucidate the inner workings of cation-exchange membrane actuation. [33][34][35] We identified solvation as the key physical mechanism underlying the actuation of cation-exchange membranes in salt solution. Solvation describes the interactions between the solvent and the dissolved solute in a solution, and plays a remarkable role in a variety of chemical and biological processes, [36,37] such as the folding of proteins.…”

Section: Introductionmentioning

confidence: 99%