Ultra-Sensitive Piezo-Resistive Sensors Constructed with Reduced Graphene Oxide/Polyolefin Elastomer (RGO/POE) Nanofiber Aerogels.

Mufang Li,Xincheng Ding,Dong Wang,Yuanli Chen,Liyan Yang,Ashish Yadav,Haiqing Jiang,Gang Sun,Weibing Zhong

doi:10.3390/polym11111883

Mufang Li, Xincheng Ding + Show 7 more

Open Access

https://doi.org/10.3390/polym11111883

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Abstract

Flexible wearable pressure sensors have received extensive attention in recent years because of the promising application potentials in health management, humanoid robots, and human machine interfaces. Among the many sensory performances, the high sensitivity is an essential requirement for the practical use of flexible sensors. Therefore, numerous research studies are devoted to improving the sensitivity of the flexible pressure sensors. The fiber assemblies are recognized as an ideal substrate for a highly sensitive piezoresistive sensor because its three-dimensional porous structure can be easily compressed and can provide high interconnection possibilities of the conductive component. Moreover, it is expected to achieve high sensitivity by raising the porosity of the fiber assemblies. In this paper, the three-dimensional reduced graphene oxide/polyolefin elastomer (RGO/POE) nanofiber composite aerogels were prepared by chemical reducing the graphene oxide (GO)/POE nanofiber composite aerogels, which were obtained by freeze drying the mixture of the GO aqueous solution and the POE nanofiber suspension. It was found that the volumetric shrinkage of thermoplastic POE nanofibers during the reduction process enhanced the compression mechanical strength of the composite aerogel, while decreasing its sensitivity. Therefore, the composite aerogels with varying POE nanofiber usage were prepared to balance the sensitivity and working pressure range. The results indicated that the composite aerogel with POE nanofiber/RGO proportion of 3:3 was the optimal sample, which exhibits high sensitivity (ca. 223 kPa−1) and working pressure ranging from 0 to 17.7 kPa. In addition, the composite aerogel showed strong stability when it is either compressed with different frequencies or reversibly compressed and released 5000 times.

Highlights

Flexible wearable pressure sensors have received extensive attention in recent years because of their benefits such as integratability, their lightweight nature, and their portability [1–7]
The results indicate that the composite aerogel with Polyolefin elastomer (POE) nanofiber/RGO proportion of 3:3 was the optimal sample, which exhibits high sensitivity, wide working pressure range (0–17.7 kPa), and strong stability either compressed with different frequencies or reversibly compressed and released for 5000 times
The lowest shape retention rate at only 14.91% appeared on the aerogel with a POE nanofiber/graphene oxide (GO) proportion of 5:1

Summary

Introduction

Flexible wearable pressure sensors have received extensive attention in recent years because of their benefits such as integratability, their lightweight nature, and their portability [1–7]. Many structures were designed and constructed to improve the device performance including sensitivity and the working pressure range. Fiber assemblies were considered as ideal substrates that can help improve the sensitivities due to their remarkable deformation ability [15–21]. When the external pressure was loaded, the porous structures constructed by the stacking fibers present larger deformation when compared to solid materials, which resulted in greater growth of the contacting areas of the conductive components. The increasing interconnection of the conductive components formed more effective conductive networks, which improves the sensitivity of the piezoresistive sensors. Research indicates that a higher porosity of the porous substrates will further strengthen the sensitivity of the piezoresistive sensors [13,22]

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