What is the primary purpose of using gel with Sonic ultrasound devices?

The primary purpose of using gel with Sonic ultrasound devices is to ensure proper sound wave conduction. In ultrasound therapy, the gel acts as a medium that facilitates the transmission of sound waves from the device to the skin and into the underlying tissues. Air is a poor conductor of sound waves, which can lead to ineffective treatment if there is no adequate coupling medium. By using gel, professionals can enhance the efficacy of the ultrasound treatment, allowing for better penetration of the sound waves, thereby improving therapeutic outcomes for the patient.

Other options propose alternative functions, but they do not align with the primary technical objective of the gel when working with ultrasound machinery.