Gradient Conductivity Boosts Flexible Tactile Sensors to Record Sensitivity and Linear Range
The intrinsic trade-off between sensitivity and linear range in piezoresistive tactile sensors has constrained their adoption in high-fidelity flexible electronics. This study introduces a layer-by-layer gradient conductivity (LGC) architecture that decouples these competing metrics. Through sequential deposition of conductive layers with decreasing filler content, the LGC resistive layer establishes a monotonic resistance–pressure relationship. The optimized LGC0.4@3 sensor achieves a record sensitivity of 0.4 kPa⁻¹ and a linear range extending to 300 kPa, as evidenced by relative electrical response measurements (Figure 1d). Dynamic monitoring of ground slope changes and convexity/concavity features (Figure 1e,f) confirms real-time operational stability. The gradient design mitigates percolation saturation, enabling linear output across three orders of magnitude. This advance addresses a critical bottleneck in tactile sensing, offering a scalable pathway for robotic proprioception and wearable health monitors. The fabrication protocol is compatible with roll-to-roll processing, with potential for cost parity against commercial capacitive sensors. Industrial translation requires further validation under cyclic loading and environmental aging, but the demonstrated metrics position LGC sensors as a viable alternative for applications demanding both high sensitivity and broad dynamic range.