Selectively insulated ultrasound transducers

An apparatus, comprising:

• a balloon configured to receive a cooling fluid;
• and
• an ultrasound transducer disposed within the balloon;
• the ultrasound transducer comprising a hollow tube of piezoelectric material having an inner surface and an outer surface, a first electrode disposed on one of the inner or outer surfaces of the hollow tube of piezoelectric material, a second electrode disposed on the other one of the inner or outer surfaces of the hollow tube of piezoelectric material, and an electrical insulator coating the first electrode and configured to inhibit the first electrode from coming into contact with the cooling fluid received by the balloon, and thereby inhibit electrical conduction between the first electrode and the second electrode when the cooling fluid received by the balloon is an electrically conductive cooling fluid,
• wherein the second electrode is not covered by an electrical insulator, and
• wherein the apparatus is configured such that the electrically conductive fluid comes into contact with the second electrode and the electrical insulator covering the first electrode when the ultrasound transducer is placed within the electrically conductive fluid;
• further comprising a backing member disposed within the ultrasound transducer, the backing member extending from a proximal end to a distal end of the ultrasound transducer and defining an interior lumen;
• and
• one or more stand-off assemblies extending from the backing member, the one or more stand-off assemblies configured to engage the second electrode;
• wherein the one or more stand-off assemblies define a plurality of openings defining an internal space between the backing member and the second electrode, the internal space being in fluid communication with an interior of the balloon via the plurality of openings so that, when in use, fluid entering the balloon passes along the first electrode and into the internal space between the backing member and the second electrode through the plurality of openings to transfer heat away from the ultrasound transducer, wherein the backing member and the one or more stand-off assemblies are coated with one or more electrical insulator materials.

A method for treating a body lumen in a mammal, comprising:

• providing an ultrasound transducer having a first surface and a second surface that are spaced apart from one another and do not intersect with one another, wherein a first electrode is disposed on the first surface, and a second electrode is disposed on the second surface;
• further providing a backing member disposed within the ultrasound transducer, the backing member extending from a proximal end to a distal end of the ultrasound transducer and defining an interior lumen;
• and one or more stand-off assemblies extending from the backing member, the one or more stand-off assemblies configured to engage the second electrode, wherein the backing member and the one or more stand-off assemblies are coated with one or more electrical insulator materials;
• covering only the first electrode with an electrical insulator;
• placing the ultrasound transducer inside of a balloon;
• exposing the ultrasound transducer to an electrically conductive fluid that comes into contact with the second electrode and the electrical insulator, and that is inhibited from coming into contact with the first electrode by the electrical insulator that covers the first electrode, wherein the exposing the ultrasound transducer to the electrically conductive fluid comprises at least partially filling the balloon with the electrically conductive fluid, wherein the one or more stand-off assemblies define a plurality of openings defining an internal space between the backing member and the second electrode, the internal space being in fluid communication with an interior of the balloon via the plurality of openings so that, during the exposing, fluid entering the balloon passes along the first electrode and into the internal space between the backing member and the second electrode through the plurality of openings to transfer heat away from the ultrasound transducer;
• while the ultrasound transducer is exposed to the electrically conductive fluid, applying a voltage between the first and second electrodes to thereby cause the ultrasound transducer to produce ultrasonic waves;
• and
• utilizing the electrical insulator, inhibiting a short circuit from occurring between the first electrode and the second electrode, while the ultrasound transducer is exposed to the electrically conductive fluid and the voltage is applied between the first and second electrodes.