Soft actuators based on electroactive polymers (EAPs) are the core constituents of future soft robots owing to their fascinating properties such as lightweight, easy fabrication into various forms, and low cost. Ionic EAP actuators are particularly attractive owing to the low driving voltages (＜ 3 V) as compared to that of electronic EAP actuators (usually kilovolts). Key challenges in the advancement of ionic EAP actuator technologies include fast response time and durability. Although several researchers have tackled these challenges over the last few decades, no breakthrough is made until recently. In this talk, I will describe a new platform for the development of soft actuators that moves a few millimeters under 1 V in air, with an unprecedented fast response time of tens of milliseconds. An essential component of this actuator is the single ion-conducting polymers that contain well-defined ionic domains; this achieved an exceptionally high dielectric constant of 78.