Dependence of force produced by polypyrrole-based artificial muscles on ionic species involved

Careem, M.A.; Vidanapathirana, K. P.; Skaarup, Steen; West, Keld

doi:10.1016/j.ssi.2004.01.080

Cited by 25 publications

(10 citation statements)

References 5 publications

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“…It is positive upon ion and solvent influx, and its magnitude depends on the number of solvent molecules accompanying the ion in its solvation shell. In cation‐exchanging materials, lower atomic weight cations, which have a higher charge density and are thus surrounded by larger hydration shells, produce greater force, and displacement …”

Section: Introductionmentioning

confidence: 99%

Characterization of Conjugated Polymer Actuation under Cerebral Physiological Conditions

Daneshvar

Smela

2014

Adv Healthcare Materials

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Conjugated polymer actuators have potential use in implantable neural interface devices for modulating the position of electrode sites within brain tissue or guiding insertion of neural probes along curved trajectories. The actuation of polypyrrole (PPy) doped with dodecylbenzenesulfonate (DBS) was characterized to ascertain whether it could be employed in the cerebral environment. Microfabricated bilayer beams were electrochemically cycled at either 22 or 37 °C in aqueous NaDBS or in artificial cerebrospinal fluid (aCSF). Nearly all the ions in aCSF were exchanged into the PPy – the cations Na+, K+, Mg2+, Ca2+, as well as the anion PO43−; Cl− was not present. Nevertheless, deflections in aCSF were comparable to those in NaDBS and they were monotonic with oxidation level: strain increased upon reduction, with no reversal of motion despite the mixture of ionic charges and valences being exchanged. Actuation depended on temperature. Upon warming, the cyclic voltammograms showed additional peaks and an increase of 70% in the consumed charge. Bending was, however, much less affected: strain increased somewhat (6-13%) but remained monotonic, and deflections shifted (up to 20%). These results show how the actuation environment must be taken into account, and demonstrate proof of concept for actuated implantable neural interfaces.

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Section: Introductionmentioning

confidence: 99%

Characterization of Conjugated Polymer Actuation under Cerebral Physiological Conditions

Daneshvar

Smela

2014

Adv Healthcare Materials

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“…Polypyrrole doped with large dodecyl benzene sulfonate anions (PPy/DBS) has been proven well suited for actuator systems operating in aqueous electrolytes [7,8]. The mechanism of actuation in this type of actuators is the insertion/expulsion of counter ions as the polymer is redox cycled between the reduced and the oxidized states [9].…”

Section: Introductionmentioning

confidence: 99%

Speed and strain of polypyrrole actuators: dependence on cation hydration number

Jafeen

Careem

Skaarup

2009

Ionics

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Polypyrrole films have been characterized by simultaneous cyclic voltammetry driven force-displacement measurements. The aim was to clarify the role of cations in the electrolyte on the speed of response and on the strain of the film. The strain as a function of actuation frequency was studied in alkali metal chloride aqueous electrolytes. The intention was to test the hypothesis of the division of the inserted H 2 O molecules into categories: a smaller number strongly bound to the cation (corresponding to the inner solvation shell) and a larger number entering the film after the insertion of the cations because of forces related to osmotic pressure difference. The two processes have very different time constants: The solvated H 2 O molecules are associated directly with the cations, and are therefore inserted in a faster process, whereas the second type enters the film much more slowly. At higher frequencies, the strain depends almost exclusively on insertion of strongly solvated cations and therefore depends on the hydration number of the cations: Li + (hydration number~5.4) gives more strain than Na + (~4.4) and much more than Cs + (~0) as predicted by the model.

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“…It shall not remain unmentioned that at present interesting work is pursued also to realize mechanical action on an electrochemical stimulus ("artifical muscles"). 48 Unlike in the case of basic storage devices (cf. the charging process of a battery) which we do not wish to subsume under this term and which we consider in the following section, here we will refer to situations in which the compositional changes caused by electricity, are meant to achieve more specific goals such as Na CO is a disadvantage.…”

Section: Electrochemical (Composition) Actorsmentioning

confidence: 99%

Solid State Electrochemistry II: Devices and Techniques

Maier

2007

Modern Aspects of Electrochemistry

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Dependence of force produced by polypyrrole-based artificial muscles on ionic species involved

Cited by 25 publications

References 5 publications

Characterization of Conjugated Polymer Actuation under Cerebral Physiological Conditions

Characterization of Conjugated Polymer Actuation under Cerebral Physiological Conditions

Speed and strain of polypyrrole actuators: dependence on cation hydration number

Solid State Electrochemistry II: Devices and Techniques

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