A novel composite material for flexible wearable devices based on eutectic gallium indium (EGaIn), multi-walled carbon nanotubes (MWCNTs) and polydimethylsiloxane (PDMS)

Despite the great potentials of bringing changes and convenience to modern life, drawbacks of current flexible sensors including low sensitivity, poor conductivity and extensibility have significantly impeded their commercialization. Herein, we propose a novel flexible film with improved performance, combining eutectic gallium indium (EGaIn), multi-walled carbon nanotubes (MWCNTs) and polydimethylsiloxane (PDMS). According to the changing ratio of resistance under different pressures, bending angles and temperature, the hybrid material appears to possess the optimal electrical conductivity at an optimal hybrid ratio of 10:1:10 (wt %) between EGaIn, MWCNTs and PDMS. In the meantime, the largest contact angle (133°), the smallest elasticity modulus (1.2 MPa), high conductivity (1.315 × 10-2 S ∙cm-1) and high resolution are achieved. Moreover, the composite material is successfully applied on PDMS substrates using brushing plastic films mask printing (BPFMP) technique to monitor the gestures of the human neck. These results prove that the new material and technologies possesses superior conductivity, flexibility, high sensitivity and low cost, easy fabrication. Therefore, it is expected to provide a supplement for flexible sensors, wearable devices and super capacitance in relation to human health monitoring and electronic tattoo.