A facile and efficient method was developed to prepare highly stretchable and conductive graphene conductors with wrinkled structures by the mechanical stretching and shrinking of elastomeric substrates, in which graphene inks were printed on a prestretched elastomeric substrate. Stretchable and exfoliated graphene inks were prepared by mixing graphite and Ecoflex in a shear-assisted fluid dynamics reactor. The resultant graphene conductor exhibited excellent stretchability at 150% strain and high electrical conductivity of 64 ± 1.2 S m− 1. The resistance of the conductor did not change in bent, twisted, and stretched states. The resistance did not change during 10,000 cycles of stretching/releasing, with a maximum strain of 150%. Based on the graphene conductor, a stretchable conductometric sensor with a two-electrode configuration was fabricated to measure impedance changes at different concentrations of electrolyte ions. This sensor exhibited a good and linear sensitivity curve (298.61 Ω mM− 1, R2 = 0.999) in bent and stretched states.

    Abstract
    1 Introduction
    2 Experimental materials and methods
        2.1 Materials
        2.2 Preparation and characterization of GEco ink
        2.3 Fabrication and characterization of GEco conductor
        2.4 Characterization of the conductometric sensor based on w-GEco conductor
    3 Results and discussion
    4 Conclusion
    Acknowledgements 
    References

• Min Sik Kil(Department of Chemical Engineering, Kangwon National University)
• Hong Jun Park(Department of Chemical Engineering, Kangwon National University)
• Jo Hee Yoon(Department of Chemical Engineering, Kangwon National University)
• Jinwu Jang(Department of Chemical Engineering, Kangwon National University)
• Kyoung G. Lee(National Nanofab Center, Center for Nano Bio Development)
• Bong Gill Choi(Department of Chemical Engineering, Kangwon National University)