Effect on Improving CO₂ Sensor Properties: Combination of HPTS and γ-Fe₂O₃@ZnO Bioactive Glass

8-Hydroxypyrene-1,3,6-trisulfonic acid (HPTS) dye, a fluorescent dye often used as a pH indicator, is embedded within the bioactive glass matrix and undergoes changes in its fluorescent properties when exposed to carbon dioxide (CO₂). The aim of the current study is to investigate the use of bioactive glass (BG) particles containing γ-Fe₂O₃@ZnO to enhance the CO₂ sensitivity of HPTS. X-ray diffraction, Fourier transform infrared, scanning electron microscopy, and photoluminescence spectroscopies were used to characterize the sol-gel synthesized powders. The sensing slides were prepared in the form of a thin film by immobilizing the fluorescent dye and γ-Fe₂O₃@ZnO-based additives into the poly(methyl methacrylate) matrix. The addition of γ-Fe₂O₃@ZnO nanoparticles with bioactive glass additives to the HPTS improves the performance characteristics of the sensor, including the linear response range, relative signal variation, and sensitivity. Meanwhile, the CO₂ sensitivities were measured as 10.22, 7.73, 16.56, 17.82, 19.58, and 42.40 for the undoped form and M, M@ZnO, 5M@ZnO-BG, 10M@ZnO-BG, and 20M@ZnO-BG NP-doped forms of the HPTS-based thin films, respectively. The response and recovery times of the HPTS-based sensing slide along with 20M@ZnO-BG NPs have been measured as 44 and 276 s, respectively. The γ-Fe₂O₃/ZnO-containing BG particle-doped HPTS composites can be used as a promising sensor agent in the detection of CO₂ gas in various fields such as environmental monitoring, medical diagnostics, and industrial processes.