This paper presents the additive manufacturing of electrically conductive polydimethylsiloxane (PDMS) nanocomposites for in-situ strain sensing applications. A straight line of pristine PDMS was first 3D printed on a thin PDMS substrate using an in-house modified 3D printer. Carbon nanotubes (CNTs) were uniformly sprayed on top of uncured PDMS lines. An additional layer of PDMS was then applied on top of CNTs to form a thin protective coating. The 3D printed PDMS/CNT nanocomposites were characterized using a scanning electron microscope (SEM) to validate the thickness, CNT distribution, and microstructural features of the sensor cross-section. The strain sensing capability of the nanocomposites was investigated under tensile cyclic loading at different strain rates and maximum strains. Sensing experiments indicate that under cyclic loading, the changes in piezo resistivity mimic, both, the changes in the applied load and the measured material strain with high fidelity. Due to the high flexibility of PDMS, the 3D printed sensors have potential applications in real-time load sensing and structural health monitoring of complex flexible structures.

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