## 1 Introduction  
Oxide thin films with large band gaps are at the forefront of materials science and engineering, offering a wealth of potential applications across various technological fields. They combine unique optical and electronic properties that pave the way for innovative applications in energy, electronics, and environmental technologies. Their continued development and refinement are essential for unlocking their full potential in future technological advancements. Metal oxide thin films, typically characterized by bandgaps ranging from 3 eV to 5 eV and more, include well-known materials, such as zinc oxide (ZnO) [1, 2, 3] or magnesium zinc oxide (MgZnO) [4, 5, 6, 7, 8, 9, 10, 11], gallium oxide (Ga\({}_{2}\)O\({}_{3}\)) [12, 13, 14], tin oxide (SnO\({}_{2}\)) [15, 16, 17], and indium oxide (In\({}_{2}\)O\({}_{3}\)) [18, 19, 20]. Their unique combination of properties, such as high optical transparency in the visible spectrum, excellent semiconducting behavior, and resistance to UV radiation, makes them particularly attractive for optoelectronic applications [21; 22; 23; 24]. One of the most promising areas for these oxide thin films is in solar energy conversion. Their wide bandgaps allow them to efficiently absorb and convert high-energy UV light, making them ideal candidates for use in dye-sensitized and perovskite solar cells, where they serve as electron transport layers. Additionally, transparent conductive oxides like indium tin oxide (ITO) play a critical role in the functionality of displays and touch screens, providing both conductivity and transparency [25; 26; 27; 28; 29]. In the realm of environmental applications, oxide thin films have shown significant potential in photocatalysis [30; 31; 32; 33], where they can facilitate chemical reactions under UV illumination. This capability is harnessed for environmental cleanup processes and water splitting for hydrogen production, showcasing their versatility beyond conventional electronic uses. As research progresses, there is a growing interest in discovering new oxide materials with even larger band gaps and improved properties. This ongoing exploration is vital for advancing the integration of oxide thin films into next-generation devices, including high-efficiency solar cells, UV photodetectors, and advanced electronic components. Microfluidics is another application filed of metal oxide films, particularly as analytical methods for biomolecules towards liquid biopsy, combining cancer-related microRNA extraction method, separation technology for biomolecules, and the detection technology [34] for microfluidic biosensing applications, including those for medical diagnostics [35; 36; 37; 38], for potentiometric pH sensing [39], and as microfluidic reactors for water purification and its applicability to volatile organic compounds [40]. Microfluidics also combines the self-assembly and nanofabrication technologies used particularly for oxide nanoparticle synthesis [41; 42; 43]. The synthesis of metal oxide films involves various techniques, including chemical vapor deposition (CVD) [44; 45; 46], magnetron sputtering [47; 48], atomic layer deposition (ALD) [49; 50], pulsed laser deposition (PLD) [51; 52; 53], and many other techniques. Each method offers distinct advantages in terms of film quality, control over thickness and composition, and scalability for industrial production. Our previous investigations demonstrated that spray pyrolysis deposition technology is suitable for producing the nanostructured wide bandgap metal oxide semiconductor films of various compositions on different substrates, with uniform morphology over large enough surfaces, with good crystallinity and optical properties applicable particularly in UV photodetectors [10; 11; 54; 12; 55]. Some insights into the impact of the chemical nature and crystallographic orientation of the substrates upon the morphology, luminescence, and wettability of ZnMgO layers produced by spray pyrolysis were revealed [56].