Skin-inspired graded Micro-Conformal tunneling interface for piezoresistive sensors with Broad-Range Ultra-Sensitivity

Flexible pressure sensors have evolved to provide high sensitivity and broad range, yet maintaining high sensitivity at elevated pressures remains challenging. Traditional approaches, which typically rely on a single strategy such as altering the contact area or the tunneling effect, often struggle to sustain high sensitivity under high pressures. Inspired by the human skin’s mechanism of opening ion channels under significant pressure, this study introduces the Graded Micro-conformal Tunneling Interface (GMTI) sensor, in which both microstructures deformation and the gradient tunneling and are brought into play. At low pressures (0–10 kPa), the sensor’s output is predominantly influenced by contact area changes, yielding sensitivity up to 6667.21 kPa⁻¹. As pressure increases, the sensor mimics skin by progressively engaging its gradient tunneling layers and expanding electronic channels, thus maintaining high sensitivity (915.08 kPa⁻¹) even at elevated pressures (10–100 kPa). Benefiting from that, the GMTI sensor can detect fluctuations as small as 200 g under car weighing 1300 kg with a resolution of 0.15 ‰. Additionally, GMTI-based insoles have been developed to measure dynamic ground reaction forces up to 2000 N during running, achieving a predictive accuracy of up to 99 %. The innovative approach offers a new strategy for pressure sensors, enabling high sensitivity even under high pressure and enhancing their applicability in measurements across an ultra-large dynamic range.