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Abstract

Atmospheric pressure non-equilibrium plasma jets in material processing have received substantial attention in the past two decades and are still in the developing stage with a growing interest in material synthesis and surface processing. The main opportunities of these techniques are their potential cost reductions in apparatus and handling. Because of their distinctive operations, atmospheric pressure plasma jets (APPJ) are easier to handle and maintain. In addition to these advantages, plasma jets provide exclusive nanomaterial synthesis and processing possibilities, placing the substrate outside the boundaries.
Subsequently, the integration into existing production lines of nanomaterials is expected to be much easier. However, great exertions are needed to optimize the process since many factors can affect it. For example, the chemical species and atmospheric conditions can affect the propagation of the plasma stream originating from the device to the open space and towards the substrate.
This work aims to fabricate a fast and reliable synthesis method for high on-demand nanoparticles, specifically plasmonically active nanoparticles for sensing applications. This work would contribute to the solution of complications in existing synthesis procedures like toxic chemical procedures used for gold nanoparticle synthesis. Atmospheric pressure plasma-driven reduction does not need any reducing agents or surfactants, with which the purification of the product would be an extra step. It could also be a promising technique for a fast, reliable, and cost-effective preparation of metal nanoparticles. It can be directly used for biological applications since the procedure is entirely non-toxic. The atmospheric pressure plasma jets can reduce the metal salts instantaneously, and thereby synthesis and depositions of metal nanoparticles happen in a single step, wherein the conventional nontoxic biological procedure would take hours or even days to complete the synthesis. In the application part, work is focused on the easy and economical synthesis of plasmonically active nanoparticles, which could be used for sensing applications in bio-nanotechnology.
To achieve the set goals, this research was focused mainly on noble metal nanoparticle synthesis, such as gold, which is widely used in different fields of applications. Before that, an appropriate plasma system was successfully built with a single electrode APPJ which allows plasma-vapor interactions that lead to the reduction of the metal salts.
However, quantitative assessment of the synthesis process by plasma-vapor interactions is complex. The results support the proposed hypothesis that the atmospheric pressure plasma jet mediates the reduction of water-soluble salts of the noble metals via plasma-vapor interactions and can replace conventional, time-consuming synthesis techniques. So synthesized nanoparticles are plasmonically active and can be used for advanced electronics or sensing applications, including bacterial DNA detection applications.
The main aim of this work is to utilize plasma jets for the reduction and deposition of metal nanoparticles, thus simplifying the complex steps in existing conventional methods.