An integrated wearable strain, temperature and humidity sensor for multifunctional monitoring

Abstract

Explosive growth in demand for wearable devices has promoted the development of smart materials with multifunctional performances. Flexible flax fabric (FF) coated with CNT and nickel serving as multifunctional sensor are prepared through a cost-effective dip-coating and electroless deposition technology. Biocompatible dopamine film self-polymerized on CNT surface effectively enhances the interfacial bonding strength between CNT and nickel coating. The conductive composite function as a strain sensor exhibits distinctive negative gauge factor and commendable repeatability during cyclic loading and unloading process. As a temperature sensor, the conductive composite also shows a negative temperature coefficient dependence and prominent behaviors including admirable sensitivity (−2.96%/℃) and long-term stability. The electrical response of the conductive composite is linear correlation with relative humidity (RH) ranging from 11% RH to 94% RH, demonstrating a relatively high sensitivity (4.73). In addition, even after suffering from acid, neutral and alkaline atmosphere for a period, the humidity sensing response is still satisfying, which illustrates the outstanding anti-corrosion properties. Therefore, the as-prepared conductive composite integrated with strain, temperature and humidity capabilities endows immense potential in wearable electronics.