Methods and apparatus for delivering a substance to a target tissue are provided which may include any number of features. One feature is storing a substance or drug in a reservoir or reservoirs over an expandable member. The expandable member can be a balloon catheter, for example. The reservoir(s) can be disposed in a Transforming Reservoirs Matrix layer disposed over the expandable member. Another feature is a mechanical activator or a plurality of mechanical activators positioned near the reservoir(s).
