Eco-Innovative Papers Integrating Nanostructured Graphenic Films. Toward Sustainable Multifunctional Integrated Sensors

: Laser-induced conductive nanofilm (LIF) electronics have gained increasing attention for their versatility and ability to form high-performing graphenic nanopatterns. Most LIF-graphenic devices are realized on plastic/polymeric substrates, while paper devices rely mainly on graphitization approaches that give rise to fragile and low-performing sensors. Thus, the manufacturing of effective graphene LIF-based paper devices suitable for real applications is still an open issue. Herein, for the first time, laser-induced reduced graphene oxide (rGO) was integrated into different cellulosic substrates to fabricate complete nanostructured paper-based sensors capable of responding to different analytical needs. Different eco-innovative cellulosic substrates were investigated, including recycled papers and papers from textile and agro-industrial wastes and manufactured with fiber alternatives to trees. Paper sensors were serially manufactured via an accessible stencil printing approach, and the rGO film was easily integrated by pressure. The paper/rGO morphological, structural/chemical, and electrical/electrochemical features were deeply investigated. Each type of paper accommodates rGO differently, leading to unique graphene film formation and chemical rearrangements affecting electrochemistry. The latter appears influenced by the paper's ability to preserve the native exfoliated nature of the rGO-film, which is dominated by sp² carbon domains. The multifunctional ability of paper-rGO sensors has been proven in various analytical applications. Reproducible data (RSD ≤ 7%), nano/micromolar limits of detection, and satisfactory recoveries (91-108%) were obtained when working with agri-food, biological, and pharmaceutical samples, proving the exploitability and high performance of paper-rGO sensors. Notably, for each application, a different paper-based sensor resulted in the best performance, proving that the cellulosic substrate directly affects the electrosensing ability.