Extreme-temperature-tolerant flexible stress sensors: Material strategies, performance challenges, and future directions

Flexible stress sensors are attracting increasing attention in wearable electronics, smart healthcare, and soft robotics due to their excellent mechanical compliance, durability, and stability. However, under extreme temperatures (typically above 100°C or below −20°C), conventional flexible materials often suffer from conductivity decay, mechanical degradation, and structural failure, severely limiting their reliability and lifespan. To address these challenges, the development of flexible stress sensors that simultaneously offer mechanical flexibility and thermal stability has emerged as a critical area of research. This review highlights recent advances in flexible stress sensors with extreme temperature tolerance, with a particular focus on material platforms including polyimide, aramid nanofibers, hydrogels, ionogels, ceramics, and block copolymers. For each system, we discuss strategies in structural design, performance enhancement, and functional integration, while also outlining current limitations and future directions for advancing next-generation flexible sensing technologies and application under harsh thermal conditions.