Yes, you can just apply serum to your face then use the Foreo, or apply an ordinary sheet mask then run the Foreo over it. The Foreo masks are tiny sheet masks made to slot on top of the Foreo, but they're quite expensive,
Each Foreo sheet mask does different things. For example, one will be for hydration, another for brightening, another for problem skin and so on. On the app, you choose the mask you're using and then the Foreo starts up, moving though different heat levels and different LED colours depending on the mask.
So you could just choose the setting for the type of serum or ordinary sheet mask you are using and do it that way. The app also talks to you in a lovely relaxing voice so it can feel like a massage in a spa.😂