Laser-Induced Graphene from Synthetic and Bioderived Precursors for Soft Electronics and Robotics

Laser-Induced Graphene (LIG) is a three-dimensional, porous material characterized by a high surface area and excellent electrical conductivity, produced through laser irradiation of various synthetic polymers with high thermal stability. Unlike conventional graphene synthesis methods, LIG offers several significant advantages: it is a one-step process that can be conducted in open air using a simple laser, eliminating the need for hazardous chemicals. Additionally, LIG fabrication is rapid, scalable, and cost-effective, suggesting it may represent a more sustainable approach to graphene synthesis compared with typical approaches. However, life cycle assessment (LCA) studies reveal that sustainability in common graphene production processes usually depends not only on the synthesis method but also on the choice of precursor materials, as these can substantially affect the environmental impacts. As a result, recent research has increasingly focused on exploring bioderived and biodegradable precursors for LIG production. After an introduction to the motivation and goals of the work, this thesis presents a comprehensive review of the state of the art, which focuses on LIG obtained from synthetic and bioderived precursors and its applications in soft electronics and robotics. The subsequent chapters focus on innovative bioderived precursors, namely starch-based bioplastics, almond shells and chitosan-based composites, and wood panels with resins from Jatropha Curcas L. seed. These materials are evaluated for their suitability as precursors for LIG synthesis, and the properties of the obtained LIG are characterized. Applications of LIG from synthetic precursors are explored in strain sensing for soft robotics and pressure sensing for object sensorization. The thesis also presents proofs of concept for LIG from bioderived precursors, showcasing its potential in different fields, such as environmental remediation and flexible electronics. Finally, a cradle-to-gate LCA of LIG is presented for the first time, demonstrating the potential sustainability of the entire production process and contrasting the environmental impacts of synthetic versus bioderived precursors. The closing chapter details the conclusions and future outlooks, emphasizing the opportunities for LIG to contribute to more sustainable practices across a wide range of applications.