Low-voltage operable conductive polymer actuators: Bioadaptive design strategies and emerging diversified applications

The persistent challenges of miniaturization, energy inefficiency, and mechanical rigidity in conventional actuators have driven a paradigm shift toward bio-inspired material systems. The conductive polymer actuators (CPAs) exhibit unprecedented advantages in bio-integrated systems, characterized by millivolt-level electrochemical responsiveness, dynamic biomimetic proprioception, and tissue-like deformability. These attributes not only transcend the limitations of traditional actuation mechanisms but also create synergistic material-structure-function relationships with biological environments. This review systematically summarizes the current progress and future trends of CPAs, with a focus on their fundamental characteristics, actuation mechanisms, design strategies, and application domains. The paper first elaborates on the fundamental characteristics of CPs, including low-voltage operation, high-efficiency response, superior flexibility/elasticity, self-sensing capabilities, cost-effectiveness/scalability, and environmental adaptability. Subsequently, it analyzes critical actuation mechanisms (redox-triggered shape morphing and ion migration-induced volumetric expansion), elucidating the underlying physicochemical principles. Furthermore, the review comprehensively discusses design strategies for CPAs, encompassing material modification, structural design, and system-level integration. Finally, representative applications are highlighted in cutting-edge fields such as biomedical and micromechanical systems, high-efficiency energy storage, smart wearable devices, bionics and robotics, along with perspectives on future research directions. This work not only provides theoretical foundations and technical guidelines for researchers but also fosters interdisciplinary collaborations, emphasizing the pivotal role of CPAs in advancing next-generation technologies. STATEMENT OF SIGNIFICANCE: This review provides a comprehensive overview of conductive polymer actuators (CPAs), highlighting their unique bioadaptive characteristics and versatile applications. By focusing on low-voltage operation, high flexibility, and self-sensing capabilities, this work underscores the potential of CPAs to revolutionize biomedical devices, smart wearables, and soft robotics. It bridges interdisciplinary fields, offering a unified framework for researchers to advance next-generation biomaterials. This review serves as a valuable guide for future research, emphasizing the transformative impact of CPAs on modern biomaterials and their critical role in addressing current technological challenges.