Wide-Range-Sensing Candle Soot/Elastomer Strain Sensors with High Sensitivity

Abstract

Nowadays, flexible resistive strain sensors attract growing attention owing to their various applications in the fields of electronic skin, human health detection, body motion, etc. Unfortunately, to date, the fabrication of a high-sensitivity soft sensor under a wide-range strain through a simple and cost-competitive approach is still a challenge. In this work, a facile polymer-surface-swelling-adhesion approach was developed to fabricate bilayer candle soot/poly (styrene-b-ethylene-butylene-b-styrene) elastic strain sensors, which obtained a high sensitivity performance at a wide range of strain. When the surface density of candle soot was 0.42 mg/cm2, the gauge factor (GF) values of the sensor were 113, 77, and 177 for various strain ranges of 0%–9%, 9%–60%, and 60%–100%, respectively. The sensor could detect tiny strains such as 0.1% and demonstrated a sensing time of 265 ms at 10% strain. Moreover, after 1000 cyclic loading-unloading at 30% strain, the relative resistance variations remain stable. The sensing mechanism was explained by the tunnel effect for low and medium strain ranges and contact resistance change for the high strain range. As a further step, respiration with a surgical mask, body motion, and road roughness were successfully monitored by using the sensor.