Development, Characterizations, and Applications of a Hand Touchable DC Plasma Needle for Biomedical Investigation

Plasma needle is a novel design of a plasma source at atmospheric pressure to achieve a nonthermal plasma jet. The advantage of the plasma needle is that it can be operated in open air, outside a vessel. The plasma that is generated with the plasma needle is small (about 1 mm) and nonthermal; the temperature of the neutral particles and ions are in about room temperature and suitably can be used to treat living biological cell without damaging the cell. In this paper, we report design, development, and electrical and optical emission spectroscopy characterization along with applicability in biomedical investigation of a dc plasma needle that can easily interact with living cell/human finger. Argon gas is used to operate the plasma needle, and the plasma jet is operated on water surface instead of human finger for stability during the characterization. The electrical diagnostics of the plasma needle shows that the discharge is pulse in nature. It has been observed that the increased in the applied voltage increasing the discharge frequency without affecting the discharge voltage and discharge current. The frequency of the discharge is found to increase almost linearly with increasing applied voltage. The estimated excitation temperature by using Boltzmann's plot method from OES is found almost independent on the applied voltage. The temperature is found to increase with increasing ballast resistance at above a threshold value of the resistance, below of which, the temperature is found almost constant. The variation in separation between the tip of the plasma needle and the water surface did not show any considerable variation in temperature when the separation is higher than 5 mm. However, considerable increase in temperature is observed when the separation is decreased below 5 mm. The developed plasma needle has been also used to treated Nova Blue bacteria and water collected from drinking water dispenser of pets, and the results shows the applicability to treat microbes in localize region.