Ecoflex-Passivated Graphene–Yarn Composite for a Highly Conductive and Stretchable Strain Sensor

) was 2.27 when a tensile strain of 50% was applied to the strain sensor. In addition, the fabricated sensor was coated with a protective layer of Ecoflex to minimize environmental effects. The passivated graphene-yarn composite sensor had a higher resistance than the unpassivated sensor because the Ecoflex film penetrated the conductive graphene nanoplates; however, the response to strains of up to 200% did not degrade after passivation. Furthermore, we demonstrated that our sensor can be used in wearable applications for monitoring individual finger movements and the wrist pulse.