The gel is spread on the skin before the ultrasonic treatment.
Aqueous active agent concentrates may either be applied before the ultrasound gel or blended with the gel.
Also oily active agent concentrates like grape seed or rose hip oil (essential fatty acids) may be used if they are first mixed with liposomes and nanoparticles and then blended with ultrasound gel.
Of course mixtures of the base gel with actives can also be applied without ultrasound. Then the mixtures correspond to high value face care gels.
General information about ultrasound gels has been published in: Ultrasound gels - effects, compositions, applications.