Design and Experimental Evaluation of an Ultrasonic Generator for the Inactivation of Gram-positive and Gram-negative Bacteria
I Ketut Putra
Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Jimbaran Campus, Badung, Bali 80361, Indonesia.
I Made Satriya Wibawa
Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Jimbaran Campus, Badung, Bali 80361, Indonesia.
I Ketut Sukarasa
Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Jimbaran Campus, Badung, Bali 80361, Indonesia.
Freygieon Ogiek Rizal Sukma
Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Jimbaran Campus, Badung, Bali 80361, Indonesia.
Anak Agung Ngurah Gunawan *
Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Jimbaran Campus, Badung, Bali 80361, Indonesia.
*Author to whom correspondence should be addressed.
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.
Keywords: Ultasonic generator, gram-positive, gram-negative, IC 555, E. coli