Investigation of the strain sensing performance of 3D-printed electrically conductive polymeric nanocomposites

Abstract

Selective laser sintering (SLS) is an additive manufacturing (AM) technology that is widely used to create complicated three-dimensional (3D) parts. Although researchers have been studying the performance of various types of powder materials, there are only a few commercially available polymers for SLS. Flexible strain sensors and their sensing capability have been appealing in human motion detection applications, since wearable electronic devices have become increasingly popular, especially for medical applications. Consequently, in this final year project, SLS 3D printing technology was utilized to fabricate electrically conductive polymeric nanocomposites. The electrically conductive polymeric nanocomposites were prepared with carbon nanotubes (CNTs) at a concentration of 2 wt%, wrapped thermoplastic polyurethane (TPU) powders. The strain sensing performance of the 3D fabricated CNT/TPU nanocomposite specimens was investigated further to evaluate their mechanical and electrical properties under tensile deformation and bending motion. The mechanical performance of specimens printed in the y-direction was found to be greater than specimens printed in the x and z-directions. Furthermore, the y-direction-printed CNT/TPU specimens displayed a significant stretchability, with an average strain of about 75%. The mechanical properties of SLS-fabricated 2 wt% CNT/TPU nanocomposites, such as the ultimate tensile strength (UTS) and the Young’s modulus, were considerably good. Both the x and y-direction-printed nanocomposites showed a relatively high gauge factor value, indicating that they are sensitive to applied strain. They responded rapidly to bending and unbending actions, paving the possibility for SLS 3D printing technology to be used to fabricate wearable electrical devices.