Tubular graphene sensors formed within planar and helical microfluidic channels

We report a helical shaped graphene strain sensor formed using a simple in situ microfluidic casting method. Fabrication of the sensor involves embedding of a helical thin metal wire into a precursor solution of elastomeric polymer, formation of a helical channel by removing the embedded metal wire from cured elastomer, and in situ casting of a thin graphene coating on the inner surface of the helical channel by filling the channel with aqueous graphene dispersion. The helical shape of the graphene sensor enables a wide detection range for both compressive and tensile strains.