Structure, principle and performance of flexible conductive polymer strain sensors: a review

This review delves into the sensing principles and structural innovations of conductive polymer strain sensors, and looks forward to their application potential in multiple fields and future research directions. Strain sensors that can convert physical deformation into electrical signals are of increasing importance amid the wider fever of the edge-cutting fields including soft robotics, human-machine interface, and wearable electronics. Yet, these more and more complex application scenarios call for a revolution of current strain sensing technologies. On top of their stretchability, more iodegradable and customizable, conductive polymer strain sensors enter the scene, showing promising prospects as next-generation strain sensors. Briefly, the sensing principles discussed include strain sensing controlled by tunneling effect, separation mechanism and crack propagation. Additionally, we explore three types of polymer strain sensor structures: filled (fiber-filled, carbon black-filled, nano-filled, and microporous-filled), sandwich (single-layer and multi-layer), and adsorption-type sensors. These sensors show great potential for applications in structural health monitoring, mechanical vibration detection, medical diagnosis, and environmental pollution monitoring. We also discuss the challenges faced by conductive polymer strain sensors and propose future research directions to address these issues. This review aims to provide a comprehensive understanding of conductive polymer strain sensors and inspire further development in this promising research area.