A highly stretchable humidity sensor based on spandex covered yarns and nanostructured polyaniline.

Ya-Nan Guo,Shi-Ying Yan,Yun-Ze Long,Xu Yan,Xiao-Xiong Wang,Li Sun,Wen-Peng Han,Zhi-Yuan Gao

doi:10.1039/c7ra10474j

Abstract

Stretchable sensors, as the important components of flexible electronic devices, have achieved progress in a variety of applications for monitoring physical or environmental conditions, such as sound, temperature, vibration, and pressure. However, it still remains a challenge to fabricate high performance stretchable humidity sensors. Herein, we present a novel stretchable humidity sensor, which was fabricated based on an ultrastretchable polyaniline composite fiber. Because of the composite fiber with a “twining spring” configuration (cotton fibers twining spirally around a polyurethane fiber) it maintains a stable electrical conductivity up to a strain of 200%. In addition, the conductivity of the composite fiber remains perfectly stable after 5000 cyclic stretching events of 200% strain. Incorporating the humidity sensitive properties of nanostructured polyaniline, the stretchable humidity sensor based on the composite fiber effectively maintains its humidity sensitivity at different elongations.

Highlights

In recent years, stretchable electronics as an emerging and interesting research scope has motivated intensive efforts from materials scientists and engineers
The high-elastic polyurethane mono lament served as the core ber and was tightly wrapped by a cotton yarn, which consists of a large amount of cotton bers, such as a compressed spring (Fig. 1a). This type of spandex covered yarns (SCYs) is carefully selected for the reason that it combines perfectly the superb elasticity provided by the core ber and increased speci c surface area by the cotton yarn, which is key to the efficient polymerization of PANI
This demonstrates that the SCY–PANI bers have a potential application in wearable devices

Summary

Introduction

Stretchable electronics as an emerging and interesting research scope has motivated intensive efforts from materials scientists and engineers. This new class of electronics has opened up a wide variety of extraordinary application elds, including stretchable displays,[1,2] wearable devices,[3] electronic eye cameras,[4] stretchable energy-storage devices,[5,6] and implantable devices for human health monitoring.[7] As an important component of integrated electrical devices, sensors perform the role of signal-input for responding various external stimulations. Many sensors based on PANI material have been fabricated successfully for application in different elds, such as chemical sensor,[8,9] gas sensor,[10,11] bio-sensor,[12,13] and strain/pressure sensor,[14] Recently the importance of humidity sensing has been well understood and a great deal of research has focused on the development of humidity sensitive materials because humidity sensors have gained increasing applications in industrial processing and 1078 | RSC Adv., 2018, 8, 1078–1082

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Conclusion