This article systematically reviews the mechanisms, material design, and cutting-edge applications of electropolymerized organic mixed ionic-electronic conductors (OMIECs) in bio-interfaces, sensing, and neuromorphic computing, emphasizing their unique advantages in enabling in situ device fabrication under low-voltage, aqueous conditions.
Literature Overview
The article, 'Electropolymerization of Organic Mixed Ionic-Electronic Conductors: Fundamentals and Applications in Bioelectronics,' published in the journal Chemical Reviews, reviews and summarizes the fundamental principles, experimental design strategies, and key applications of organic mixed ionic-electronic conductors (OMIECs) fabricated via electropolymerization in the field of bioelectronics. The article systematically elaborates on the functional mechanisms of OMIECs in bio-interfaces, biosensing, and neuromorphic synaptic devices, with a focus on analyzing the relationships between material properties, polymerization conditions, and device performance. Additionally, the authors discuss current challenges and future research directions, offering theoretical guidance and practical pathways for developing implantable, programmable, and biocompatible electronic devices. This review holds significant importance in advancing the integration of bioelectronics with flexible electronic technologies.Background Knowledge
Organic mixed ionic-electronic conductors (OMIECs) are a class of conducting polymers capable of simultaneously transporting electrons and ions. Due to their excellent electrochemical stability, good mechanical flexibility, and ion-transport capabilities compatible with biological systems, OMIECs have become core materials in bioelectronics. Traditional conducting polymers such as polypyrrole (PPy), polyaniline (PANI), and polythiophene (PEDOT) typically require electropolymerization in organic solvents, limiting their direct application in physiological environments. In recent years, the development of water-soluble monomers has enabled electropolymerization in aqueous phases, allowing in situ construction of electrodes or sensors within living tissues, greatly enhancing device biocompatibility and integration. In neural interfaces, OMIECs can reduce electrode impedance and improve signal-to-noise ratios, supporting high-precision neural recording and stimulation. In biosensing, their volumetric capacitance can amplify ionic signals, enabling highly sensitive detection of molecules such as pH, glucose, and DNA. In neuromorphic computing, electrochemical transistors based on OMIECs can simulate synaptic weight modulation, enabling low-power information processing. However, precise control over polymer morphology, optimization of ion/electron mobility, and long-term stability remain key challenges. This review systematically addresses the synthesis mechanisms and application progress of electropolymerized OMIECs, providing comprehensive guidance for the design of next-generation bio-integrated electronic devices.
Research Methods and Experiments
This article systematically analyzes the experimental design elements of electropolymerized OMIECs through a literature review, covering material selection, polymerization mechanisms, electrode configurations, and in situ characterization techniques. The authors discuss in detail how monomer structures affect oxidation potential, hydrophilicity, and film-forming properties, compare the electropolymerization behaviors of different thiophene derivatives (e.g., EDOT, ETE, EEE), and explain the regulatory roles of solvents, electrolytes, electrode materials, and surface pretreatment on the polymerization process. Additionally, the article introduces various electrochemical polymerization setups, including two-electrode, three-electrode, transistor configurations, bipolar arrangements, and novel strategies for electropolymerization at immiscible liquid–liquid interfaces. To monitor the polymerization process in real time, the authors summarize the application of in situ characterization techniques such as cyclic voltammetry, conductivity measurements, quartz crystal microbalance with dissipation (QCM-D), and spectroscopic methods.Key Conclusions and Perspectives
Research Significance and Prospects
This review provides researchers with a comprehensive knowledge framework for electropolymerized OMIECs, from molecular design to device integration, advancing the rational design of bioelectronic materials. Future research directions include developing OMIECs with higher stability, faster response, and biodegradability, exploring heterostructures of multiple materials, and achieving precise fabrication of complex three-dimensional microstructures.
Furthermore, integrating electropolymerization techniques with bioprinting and microfluidic systems holds promise for realizing fully integrated, programmable bioelectronic devices for real-time monitoring and modulation of biological processes. In neural interfaces, in situ electropolymerization could enable seamless integration of flexible electrode arrays with neural tissues, enhancing long-term recording stability. In disease diagnostics, OMIEC-based electrochemical sensors could enable label-free, real-time detection of biomarkers, showing strong potential for clinical translation.
Conclusion
This article comprehensively summarizes the scientific foundations and bioelectronic applications of electropolymerized organic mixed ionic-electronic conductors (OMIECs). OMIECs demonstrate significant potential in bio-interfaces, sensing, and neuromorphic computing due to their unique ion-electron cooperative conduction mechanisms. Electropolymerization technology is particularly suitable for constructing implantable and programmable bioelectronic devices, as it enables localized, controlled growth of conducting polymers under aqueous, low-voltage conditions. By rationally designing monomer structures and optimizing polymerization parameters, the electrical conductivity, ion permeability, mechanical properties, and biocompatibility of the materials can be precisely tuned. This review not only systematically compiles current research progress but also highlights challenges in material stability, long-term performance, and manufacturing precision. In the future, with the development of new water-soluble monomers and advances in in situ characterization techniques, electropolymerized OMIECs are expected to find broader applications in neural engineering, wearable sensing, and intelligent medical devices, driving bioelectronics toward higher integration, enhanced functionality, and better biological integration.
