Fig. 2

Electromechanical performance of MWCNT/graphene hybrid sensor. a Strain sensing characteristic of the MWCNT-based sensor according to the mass of the coated MWCNTs (unit: mg). b Strain sensing characterization of MWCNT-, graphene-, and MWCNT/graphene hybrid-based sensors with different mass ratios. For both a and b, the partially enlarged views of the relative resistance change in the sensors at a strain range of 0–300% are depicted below them. Loading speed for all experiments is 2 mm/s. c GF of the MWCNT-, graphene-, and MWCNT/graphene hybrid-based sensors in a strain range of 0–700% for a 50% strain step. The strain sensor prepared by spray coating 0.36 mg graphene has the largest GF (~ 34,101.5), but the sensing range is limited to 330%. In contrast, the strain sensor composed of a hybrid of 1D MWCNT and 2D graphene with a mass ratio of 1:2 exhibits both a high GF of 12,144.7 (at a strain range of 650% ~ 700%) and a high sensing range of 710.5%