Measuring and monitoring through wearable technology parameters related to human movement, posture, and gesture are gaining momentum because of their wide range of potential applications in daily-life conditions. In previous studies, carbon elastomers (CEs) have been used as strain sensors. Recent developments of CE sensors mathematical modeling demonstrated that the CEs can be used as electrogoniometers. It was proved that for small local curvatures of CE layers, the resistance of a strip constituting a layer depends only on the total curvature of the same layer and not on the particular shape that the sensor keeps in adherence with a surface. Further, it was proved, theoretically and experimentally, that a double-layer configuration provides better accuracy with respect to a single-layer configuration. These results have been obtained under the hypothesis that the device was bent, but not extended. In this paper, we substituted the inextensible insulating layer in the sensors with an elastic one, allowing the system to extend its length. This improvement required further study to make it fit for biomechanical applications following epithelial deformations produced by joint movements and minimizes skin motion artifacts.