3D printed polymer graphene nanocomposites for bio-sensor applications

Abstract

Prosthetic technology lacks effective, 3D-printable strain sensors for enhancing sensory feedback. This study explores the potential of thermoplastic polyurethane (TPU) and polyamide 11 (PA11) blends with graphene nanoplatelets (GNPs) to address this challenge. The composites were extruded using a twin-screw extruder. Raman spectroscopy and atomic force microscopy (AFM) were used to analyse GNPs. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were conducted on neat polymers and composites to characterise the sample thermally. Structural analysis was done via X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman mapping and oscillating rheology. Tensile testing was carried out on filaments and 3D-printed dumbbells according to relevant ISO standards 2062 and 527, respectively. Electrical testing was done on all the samples, and electro-mechanical testing was done on all samples in which the resistance could be detected on a standard multimeter. In TPU, 1.5 wt. % GNP loading optimised phase separation and order; however, more importantly, the ductility properties of the TPU were not affected by the presence of GNPs. In PA11, an electrical percolation threshold was achieved at 7.9 wt% GNPs, yielding a gauge factor of 13.25 ± 3.31 at 10 wt. %. The TPU/PA11 blend maintained TPU's ductility while incorporating PA11's electrical properties. Single-material FDM printing of TPU//PA11/10GNP blend achieved a gauge factor of 1.63 ± 0.08, outperforming dual-material prints. This study demonstrates the feasibility of creating a 3D-printable TPU/PA11/GNP composite material with strain-sensing capabilities, potentially advancing the development of more responsive prosthetic devices.

Thesis embargoed until 31 July 2030.

Date of Award	Jul 2025
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Northern Ireland Department for the Economy
Supervisor	Oana Istrate (Supervisor) & Biqiong Chen (Supervisor)