Sustainable Wood-Based Electronics Towards Smart Buildings
EMBARGOED UNTIL 2028-12-31
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Date
2025
Publication Type
Doctoral Thesis
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EMBARGOED UNTIL 2028-12-31
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Abstract
The transition from conventional construction practices to smart building technologies is reshaping how we design, inhabit, and interact with our built environments, offering real-time monitoring of environmental conditions and occupant behavior, and enhanced energy performance through adaptive control systems that optimize building operations. However, this advancement comes at a cost: the widespread use of sensors, control systems, and embedded electronics relies on rare, non-renewable resources and energy-intensive manufacturing, leading to significant environmental impacts and the accumulation of electronic waste. Reconciling these technological benefits with long-term sustainability goals remains a pressing and multifaceted, complex challenge.
Motivated by this context, this thesis investigates iron-catalyzed laser-induced graphitization (IC-LIG), presented as a novel, eco-efficient approach that transforms wood from a passive substrate into an electrically conductive material, with the aim of contributing to the development of sustainable materials for future building technologies. The first step involves the application of a bio-based precursor ink, composed of tannic acid and iron salt, which smooths surface irregularities and facilitates catalytic graphitization. In the second step, CO₂ laser irradiation under ambient conditions induces localized graphitization via iron-catalyzed laser-induced graphitization, beginning with thermal decomposition and precarbonization of the precursor ink in the heat-affected zone, and yielding conductive graphitic structures with high electrical performance. This is achieved without the need for fire retardants, inert atmospheres, or complex laser systems, thereby streamlining the process and enhancing its scalability and compatibility with potential industrial manufacturing. As a result, sensing, energy storage, and interactive touch functionalities have been demonstrated in first proof-of-concept devices, highlighting the potential for direct integration into wood-based (construction) materials and alignment with the renewability and carbon storage potential of wood.
Over the course of three publications, this thesis establishes IC-LIG as a scalable and versatile platform for the laser-based fabrication of functional carbon structures on wood. The first study introduces the IC-LIG approach and demonstrates its feasibility for large-scale processing, enabling the creation of conductive patterns with areas reaching up to 100 cm² on various wood species under ambient conditions. The second study investigates the catalytic mechanisms and structural evolution underlying laser-induced graphitization by analyzing the cross-sectional transition zone spanning untreated precursor ink to fully graphitized IC-LIG. This approach reveals a hierarchically layered electrode structure and enables the construction of a 3D model that integrates nanoscale insights within a mesoscopic framework. Based on post-process observations, it traces the migration and growth of catalytic iron nanoparticles across the IC-LIG electrode, highlighting their inferred role in the graphitization process. The third study focuses on process optimization towards industrial scalability, demonstrating that variations in the tannic acid-to-iron (TA:Fe) ratio directly affect ink rheology, which in turn enables diverse application methods, including spray coating, screen printing, and direct ink writing. These ink alterations influence the electrode architecture and electrochemical behavior for prospective energy storage applications.
Collectively, these findings position IC-LIG as a promising approach for advancing green electronics that balances performance and scalabil-ity, with environmental sustainability identified as a potential avenue for fu-ture exploration, particularly through life cycle assessment (LCA). The IC-LIG platform reflects a broader, interdisciplinary vision for sustainable innovation in the built environment. By rethinking both materials and methods, this work marks a significant step within the emerging landscape of sustainable electronics toward integrating electronics directly into renewable building materials. While practical implementation challenges such as long-term environmental stability and integration with conventional electrical systems remain to be addressed, this work contributes to a future where buildings are not only smart, but fundamentally sustainable, bridging disciplines and fos-tering collaboration among materials scientists, engineers, architects, de-signers, and circular economy stakeholders.
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Examiner : Burgert, Ingo
Examiner : Schnepp, Zoe
Examiner : Kaltenbrunner, Martin
Examiner : Panzarasa, Guido
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ETH Zurich
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Subject
sustainable electronics; CARBON ELECTRODES (ELECTRICAL ENGINEERING); Iron catalyst; laser induced graphene; Sensors; WOOD + TIMBER (BUILDING MATERIALS); Wood; Interfaces
Organisational unit
03917 - Burgert, Ingo / Burgert, Ingo