In such matters, the essential criterion is whether water can reach the skin. If the device prevents water from reaching the skin, it invalidates both wudu (ablution) and ghusl.
However, if the device is part of a necessary medical treatment and there is no viable alternative, it may be regarded similarly to a bandage placed over a wound. In this case, it is sufficient to wipe (masah) over it during wudu or ghusl.