Design and Experimental Evaluation of an Ultrasonic Generator for the Inactivation of Gram-positive and Gram-negative Bacteria

Abstract

This research presents the design and experimental application of an ultrasonic generator based on an IC 555 timer as a source of ultrasonic waves for bacterial inactivation. The developed system operated in the frequency range of 40–65 kHz and was experimentally evaluated using Gram-positive and Gram-negative bacterial suspensions with fixed initial concentrations. The Gram-positive bacterium used in this study was Staphylococcus aureus, while the Gram-negative bacterium was Escherichia coli.Bacterial samples were exposed to ultrasonic radiation at various frequencies and irradiation distances for a fixed irradiation time of 10 minutes. The effectiveness of ultrasonic treatment was evaluated based on bacterial mortality percentage and average bacterial reduction (CFU/mL). The results show that bacterial mortality increases with increasing ultrasonic frequency for both Gram-positive and Gram-negative bacteria. Under identical irradiation conditions, Gram-negative bacteria consistently exhibited higher mortality than Gram-positive bacteria. In addition, shorter irradiation distances resulted in higher bacterial inactivation efficiency for both bacterial groups.