Multifunctional flexible thermoelectric devices for next-generation wearable and integrated systems

Flexible thermoelectrics (f-TEs) are being developed rapidly due to their unique advantages, such as direct conversion between electricity and thermal energy, compatibility with curved heat sources, and ease of integration. Over the past decade, significant progress has been made in enhancing the overall performance of f-TE materials and devices, particularly in terms of output power, mechanical flexibility, and durability. Recent research efforts are increasingly focused on translating these advancements into practical applications across diverse fields. For example, f-TE-based multimodal sensors are capable of simultaneously detecting temperature, pressure and strain. In biomedicine, f-TE generators are being explored for wound healing, antibacterial therapy, and neural modulation. Furthermore, f-TE devices show promise in personalized thermal management and hybrid energy harvesting systems. This review moves beyond material preparation and device optimization to focus on the expanding multifunctional applications of f-TEs. We provide a broad perspective by comprehensively exploring the latest progress of f-TEs in intelligent sensing, biomedicine, personalized thermal management, and multifunctional hybrid systems. Key challenges are also discussed, including the development of high-performance flexible devices, robust bio-interfaces, ensuring long-term stability, and achieving intelligent integration with data-driven algorithms and multimodal platforms. Finally, we offer insights into future directions for f-TEs, pointing toward next-generation intelligent and bio-integrated flexible electronics.