Ion-electron cooperative modulation for wide-range linear and high-sensitivity strain sensing in human motion monitoring and prosthetic assistance.

Flexible and stretchable strain sensors are critical components for motion-related sensing systems. However, achieving high sensitivity together with a wide linear detection range remains a persistent challenge due to the intrinsic trade-off between these two performance metrics. Here, we propose an ion-electron cooperative strain sensor based on a core-shell fiber architecture, in which an ionically conductive elastomeric core is integrated with an electronically conductive graphene shell. By constructing dual charge-transport pathways within a single device, the sensor exploits electronic transport dominated by microcrack propagation in the small-strain regime, while gradually transitioning to ion-dominated transport under large deformation to maintain continuous conduction over an ultrawide strain range. Importantly, the formation of an ion-electron interphase at the core-shell interface enables smooth redistribution of conduction weights through cooperative modulation, resulting in high linearity across the entire strain range. The sensor achieves ultrahigh gauge factor (34,748.3) together with excellent linearity (0.99899) over a broad strain range of 12.5%∼250%. This work is expected to propose a general multi-carrier cooperative modulation principle that offers new mechanistic insight into overcoming intrinsic performance limitations in flexible strain sensors.