A Flexible Impact Sensor of Interpenetrating‐Phase Composite Architecture with High Mechanical Stability and Energy‐Absorbing Capability

Abstract Flexible electromechanical sensors frequently suffer from unexpected impact loadings caused by slipping, collisions and falling objects, to name a few. Without sufficient protection, these undesired impacts would lead to critical mechanical instability even damage to flexible sensors, resulting in restricted measurement range and imprecise sensing. Thus, it is of significance, but still is a fresh challenge to enhance the mechanical stability and energy‐absorption capacity of flexible sensors under impacts. Here, a multi‐design strategy is proposed to construct an interpenetrating‐phase cellulose‐acetate composite (IPC²) architecture for flexible sensors in impact‐intensive sensing applications. The external structure mimics bellows‐morphology of beverage‐straws that deform in programmed loading direction to enhance the mechanical stability, while the internal conductive core has a co‐continuous interpenetrating‐phase architecture that can efficiently absorb impact energy. Systematic numerical analysis and experimental tests demonstrate that IPC² architecture presents excellent structural stability, cyclic performance and a unique combination of exceptional specific energy absorption (SEA = 2.66±1.2 kJ kg⁻¹), low density (ρ = 720±10 kg m⁻³), electromechanical properties (GF≈39.6). Remarkably, the recovery behaviors in terms of shape and electrical signals show good repeatability and reliability. This study offers a new composite framework to exploit the potentialities of flexible sensors with protective functions and commercial values.