Industry 4.0-Driven Circular Manufacturing: Upcycling End-of-Life Smartphone Screen Glass Through Additive Manufacturing

Electronic waste from end-of-life smartphones has grown into one of the most significant and poorly managed material streams of our era. Within this stream, chemically strengthened glass - the aluminosilicate screens found in nearly every modern device - is consistently overlooked. While precious metals are extracted, the glass is either landfilled or melted into low-grade cullet, destroying the very properties that make it valuable. This paper presents a systematic review of literature spanning smart glass recovery, Industry 4.0-enabled sorting technologies, and additive manufacturing with recycled inorganic feedstocks, and uses these to develop an integrated circular manufacturing framework for the closed-loop recovery and remanufacturing of end-of-life smartphone screen glass. The framework links laser-induced breakdown spectroscopy (LIBS)-based sorting for grade-specific glass classification with paste extrusion additive manufacturing to produce high-performance optical, architectural, and medical-grade components from recovered material. A structured search across Web of Science, Scopus, ScienceDirect, and Google Scholar yielded a final reference set of 25 sources (18 from systematic screening; 7 from citation chaining). The Global E-Waste Monitor 2024 reports that global e-waste generation reached 62 million tonnes in 2022, and the review finds that each component of the proposed pathway is technically validated in adjacent domains. Their integration into a coherent circular system is both feasible and economically promising - particularly given tightening Extended Producer Responsibility regulation in the EU and elsewhere. This study is conceptual in nature; while empirical validation - particularly for aluminosilicate glass additive manufacturing - remains a critical priority for future research, the proposed framework offers a structured pathway for transitioning from bulk recycling to value-preserving circular manufacturing systems for chemically strengthened glass.