Development and optical characterization of an atmospheric pressure non-thermal plasma jet for superhydrophobic surface fabrication

Atmospheric pressure non-thermal plasma jets are becoming subject of great attention in various fields such as plasma processing and biomedical applications due to their ability to produce highly reactive species and good reaction chemistry at low gas temperatures. In the present study, a non-thermal plasma jet operating on argon gas at atmospheric pressure aimed mainly towards surface modification and thin film deposition applications has been developed. Optical emission spectroscopy is used to evaluate the plasma parameters. The gas temperature (800 ± 50 K) is estimated from OH(A-X) rotational band. The excitation temperature is measured using intensity ratio of two argon lines and is found to be 0.241–0.273 eV and the corresponding electron temperatures have been measured. Electron density of the order of 1014 cm−3 has been obtained from the Stark broadening of Balmer H β line. The plasma jet has been successfully employed to deposit a superhydrophobic thin film of SiwCxHyOz using hexamethyldisiloxane (HMDSO) precursor monomer. The deposited film has been analyzed using XRD, FTIR, SEM, AFM, and contact angle analyzer. All the treated surfaces have shown superhydrophobic property with a contact angle greater than 150° showing numerous potential in various applications. This method is a relatively easy and environmental friendly way of fabricating superhydrophobic surfaces.