Design and 3D Printing of GelMA-Based Conductive Hydrogels for Wearable Strain Sensors

In this thesis, a conductive hydrogel based on Gelatin Methacryloyl (GelMA) was developed and thoroughly characterised for its application in flexible strain sensors and advanced 3D printing using Digital Light Processing (DLP) technology. Mechanical testing under tensile and compressive loads was performed, along with additional assessments of bending resistance, durability, and general degradability, in order to evaluate the material’s structural integrity and long-term performance. The incorporation of tannic acid (TA) into the GelMA matrix significantly enhanced the mechanical properties, adhesion to various substrates, and printability of the hydrogel. Notably, the tensile strength of the hydrogel approximately doubled following TA addition, indicating a substantial improvement in robustness and resistance to failure under load. Furthermore, TA facilitated improved interfacial bonding and shape fidelity during the printing process, allowing the fabrication of complex 3D geometries with high spatial resolution and structural stability. Optimisation of key DLP parameters—such as exposure time, layer thickness, and photoinitiator concentration—enabled reproducible printing of intricate constructs with fine detail and minimal distortion. These findings demonstrate that GelMA/TA composites represent a versatile and promising platform for the fabrication of next-generation wearable biosensors, combining biocompatibility, mechanical resilience, and compatibility with high-resolution additive manufacturing techniques.