Ionic EAP Actuators with Electrodes Based on Carbon Nanomaterials

Abstract

Flexible polymer-based actuators, often also called artificial muscles, are an essential part of biomimetic systems that mimic the movement principles of animal world creatures. The most used electrode material to force the actuator move is an ensemble of noble metal nanoparticles in the electroactive polymer surface. Noble metal electrodes have enough electrical conductivity and elasticity and are not subjected to oxidation. However, high cost of such electrodes and their tendency to cracking dictate the need for searching other materials, primarily carbon ones. The review considers several options for this search. For example, carbon nanotubes and graphene have excellent properties at the level of a single individually taken nanotube or graphene sheet. However, conservation of these properties in structurally imperfect film electrodes requires a separate study. In addition, there are problems of compatibility of such electrodes with the polymers that requires cumbersome technologies, e.g., hot pressing, which complicates the production of the actuator as a whole. The review concerns the technology options of manufacturing actuators and the results obtained on their basis, both including hot pressing and avoiding this procedure. In particular, the required level of the graphene oxide reduction in hydrazine provides sufficient adhesion at rather high electrical conductivity of the graphene film. The ability to simultaneous achieving these properties is a nontrivial result, providing the same level of actuation as with expensive noble metal electrodes. Actuators that additionally require greater lifetime resource should be obtained in other ways. Among them are using the graphdiyne electrodes and laser processing of the graphene electrodes.

High-frequency and rapid response tungsten sulfide nano onion-based electrochemical actuators

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Only a little data are available for ionomeric polymer-metal composite (IPMC)-like actuators operating above 1 Hz in air. [21][22][23][24][25][26][27] While the air-working IPMCs have a limited displacement retainability compared with their actuations at relatively low frequencies, there is still a great challenge to retain half and a tenth of the actuation displacement at 0.1 Hz when their working frequency reaches 1 Hz and 10 Hz, respectively. Moreover, they can hardly actuate in liquids due to a huge viscous resistance, let alone at 1 Hz and beyond, arresting their development in underwater devices.…”

Enhancement in Capacitance of Ionic Type of EAP-Based Strain Sensors

“…EAPs are typically made from organic polymers, such as plastics or rubbers, chemically modified to allow for electrical conductivity. The conductivity can be achieved through the incorporation of conductive particles, such as carbon or metals, into the polymer matrix [45][46][47][48]. Incorporating conductive particles into the polymer matrix is a fundamental method to enhance electrical conductivity in EAPs.…”