| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 738907 | Sensors and Actuators A: Physical | 2015 | 7 Pages |
•We showed that the lithium salt LiClO4 dissolved in propylene carbonate, a low vapor pressure organic solvent, gives an ionic solution that can be used. The non-aqueous ionic solution has the advantages of a low vapor pressure and high dielectric permittivity, which can allow better IPMC activation in air.•The lifetime of the parylene-coated Ag-IPMC with non-aqueous solution is 15 times the length of that for the uncoated Ag-IPMC with aqueous solution.•The non-aqueous ionic solution IPMCs show promising potential in dry air operation compared to IPMCs with aqueous solution. The Ag-IPMC has advantages in terms of durability and the low driving voltage (∼10% less). It can thus be further developed to eventually replace the Pt-IPMC.•We have presented several aspects that are related to IPMC performance in dry air. The electrolysis and evaporation problems have been minimized in this work. We showed that enhancement of electrodes can further improve the reliability of IPMCs in dry air.
Electroactive polymers (EAPs) are capable of exhibiting large shape changes in response to electrical stimulation. EAPs can produce a large deformation with a low applied voltage for actuation applications. The IPMC (Ionic Polymer Metal Composite) is a well-known type of ionic EAP. It has numerous attractive advantages, such as low electrical energy consumption and being lightweight. The underlying mechanism of an IPMC actuator is the ionic diffusion when a voltage gradient is applied. As such, the characteristics of the ionic solution have a large impact on the physical properties of the IPMC. In this paper, reliability tests of IPMCs with a non-aqueous ionic solution are demonstrated. The Pt-IPMC with LiOH aqueous solution exhibits the best maximum displacement, but the water in the LiOH solution is electrolyzed easily because of the low electrolysis voltage (1.23 V) of water. To ameliorate the electrolysis problems and improve the operation time, more appropriate solvents with a high electrolysis voltage and low vapor pressure should be chosen. Parylene-coating can also protect the IPMC from solvent loss. The reliability tests focus on the durability of IPMCs in dry air. Improvements in IPMC fabrication, such as Ag-IPMC, are discussed in this paper. Through the use of parylene protection and an ionic solution with a high electrolysis voltage, the lifetime of the Ag-IPMC in dry air is up to 15 times greater than that of the uncoated Ag-IPMC with aqueous solution. We have addressed potential issues regarding the dry air actuation of IPMCs, and found that the cracking of electrodes has a major impact on the reliability of the IPMCs in this study.
