Composite elongation causes an increase in electrical resistance by breaking conductive paths, which is larger for narrow elements made of conductive CB-PLA. Internal stresses should be avoided as they might affect the reproducibility of the electrical characteristics. The  ~ 0.07 exceeds the GF by one order of magnitude, and surpassing this elongation leads to a plateau region connected with different flexural strengths between the CB-PLA and PLA. However, the prolonged mechanical stresses effect on the electrochemical characteristic is negligible since [Fe(CN)6] 4-/3-peak currents were shifted by not more than 6% even after 20 MPa tensile load. PLA composites become brittle when reinforced, necessitating mechanical testing to determine if they can be used in applications such as detection cells, test strips and wearable sensors (point-of-care or wearables). Joining two materials for electrical insulation requires a stable interface that does not spontaneously crack or fail under small forces to enable integrated system construction using 3DP targeted at environmental or biomedical monitoring.