Ultrasensitive mechanical crack-based sensor inspired by the spider sensory system

Abstract

Recently developed flexible mechanosensors based on inorganic silicon1–3, organic semiconductors4–6, carbon nanotubes7, graphene platelets8, pressure-sensitive rubber9 and self-powered devices10,11 are highly sensitive and can be applied to humanskin.However, the development of amultifunctional sensor satisfyingthe requirementsofultrahighmechanosensitivity, flexibility and durability remains a challenge. In nature, spiders sense extremely small variations inmechanical stress using crack-shaped slit organs near their leg joints12.Herewedemonstrate that sensors based on nanoscale crack junctions and inspired by the geometry of a spider’s slit organ can attain ultrahigh sensitivity and servemultiple purposes. The sensors are sensitive to strain (with agaugefactorofover 2,000inthe0–2percentstrainrange)andvibration (withthe ability todetectamplitudes of approximately 10 nanometres). The device is reversible, reproducible, durable andmechanically flexible, and can thus be easily mounted on human skin as an electronic multipixel array.Theultrahigh mechanosensitivity is attributed to the disconnection–reconnection process undergone by the zip-like nanoscale crack junctionsunder strain or vibration.Theproposedtheoretical model is consistent with experimental data that we report here. We also demonstrate that sensors based on nanoscale crack junctions are applicable to highly selective speech pattern recognition and the detection of physiological signals. The nanoscale crack junction-based sensory system could be useful in diverse applications requiring ultrahigh displacement sensitivity.