A piezoelectric actuator comprising an optimum layer structure when orientation strontium ruthenate is used as a bottom electrode is provided. The operation provides for generating higher temperatures in deeper layers of tissue relative to shallower layers of tissue. The vial gate comprises a delivery lumen, suitable for delivering the drug from the vial to the delivery tube; and a vent lumen, suitable for providing a replacement fluid from a location inside the tubing set to the inside of the vial in order to replace the delivered drug.