Enhanced ultrasound imaging probes using flexure mode piezoelectric transducers

A method of generating an enhanced receive signal from a piezoelectric ultrasound transducer, the method comprising:

• providing a piezoelectric ultrasound transducer, the piezoelectric ultrasound transducer comprising a piezoelectric element operable in flexural mode;
• applying a sine wave bipolar transmit cycle pulse to the piezoelectric element to produce an acoustic signal providing an acoustic echo, the sine wave bipolar transmit cycle pulse having a maximum peak voltage;
• receiving the acoustic echo by the piezoelectric element, the acoustic echo convertible to an electrical voltage by flexural mode resonance of the piezoelectric element;
• applying a DC bias to the piezoelectric element prior to receiving the acoustic echo and/or concurrently with receiving the acoustic echo;
• and
• generating an enhanced receive signal from the piezoelectric transducer by converting the received acoustic echo to an electrical voltage by flexural mode resonance of the piezoelectric element;
• wherein the enhanced receive signal generated by the piezoelectric transducer is greater than a receive signal generated by the piezoelectric transducer in the absence of applying a DC bias.

An ultrasound imaging catheter comprising:

• a housing having a distal end for insertion into and manipulation within a vascularized organism and a proximal end for providing a user with control over the manipulation of the distal end of the catheter within the vascularized organism;
• and
• a piezoelectric ultrasound transducer positioned within the housing proximal to the distal end of the housing, the transducer comprising:
• a substrate;
• a plurality sidewalls defining a plurality of openings through the substrate;
• spaced-apart bottom electrodes on the substrate, wherein each spaced-apart bottom electrode spans one of the plurality of openings;
• spaced-apart piezoelectric elements on each of the bottom electrodes;
• a conformal conductive film on each of the sidewalls of the plurality of openings, each conformal conductive film in contact with the bottom electrodes through the substrate, wherein open cavities are maintained in each of the openings.

An ultrasound imaging catheter comprising:

• a housing having a distal end for insertion into and manipulation within a vascularized organism and a proximal end for providing a user with control over the manipulation of the distal end of the catheter within the vascularized organism;
• and
• a piezoelectric ultrasound transducer positioned within the housing proximal to the distal end, the transducer comprising:
• a substrate;
• a plurality of sidewalls defining a plurality of openings partially through the substrate;
• spaced-apart piezoelectric elements on the substrate, wherein each spaced-apart piezoelectric element is positioned over one of the plurality of openings;
• pairs of spaced-apart bottom electrodes on the substrate and each pair of spaced-apart bottom electrodes are in contact with each of the spaced-apart piezoelectric elements;
• a conformal conductive film on each of the sidewalls of the plurality of openings, each conformal conductive film in electrical interconnection with the bottom electrodes through the substrate, wherein open cavities are maintained in each of the openings;
• a ground pad on the substrate;
• a second dielectric film between the piezoelectric elements;
• a top electrode in contact with the piezoelectric elements and the ground pad;
• and
• a semiconductor device attached to the ultrasonic transducer, wherein the conformal conductive film is electrically connected to the semiconductor device.

An ultrasound imaging probe comprising:

• a housing having a distal end;
• a piezoelectric ultrasound transducer positioned within the housing proximal to the distal end, the transducer comprising:
• a substrate;
• a plurality of sidewalls defining a plurality of openings through the substrate;
• spaced-apart bottom electrodes on the substrate, wherein each spaced-apart bottom electrode spans one of the plurality of openings;
• spaced-apart piezoelectric elements on each of the bottom electrodes;
• and
• a conformal conductive film on each of the sidewalls of the plurality of openings, wherein each conformal conductive film is contact with one or more of the bottom electrodes and open cavities are maintained in each of the openings;
• and
• means for applying a DC bias to the piezoelectric transducer.

An ultrasound imaging probe comprising:

• a housing having a distal end;
• a piezoelectric ultrasound transducer positioned within the housing proximal to the distal end, the transducer comprising:
• a substrate;
• a plurality of sidewalls defining a plurality of openings through the substrate;
• a first dielectric layer on the substrate;
• spaced-apart bottom electrodes on the first dielectric layer;
• each spaced-apart bottom electrode spanning one of the plurality of openings;
• spaced-apart piezoelectric elements on each of the bottom electrodes;
• a conformal insulating film on each of the sidewalls of the plurality of openings;
• a conformal conductive film on each of the conformal insulating films, wherein each conformal conductive film is in contact with one or more of the bottom electrodes and an open cavity is maintained in each of the openings;
• a ground pad on the substrate;
• a second dielectric film between the piezoelectric elements;
• a top electrode in contact with the piezoelectric elements and the ground pad;
• and
• a semiconductor device attached to the ultrasonic transducer, wherein the conformal conductive film is electrically connected to the semiconductor device;
• and
• means for applying a DC bias to the piezoelectric transducer.

An ultrasound imaging probe comprising:

• a housing having a distal end;
• a piezoelectric ultrasound transducer positioned within the housing proximal to the distal end, the transducer comprising:
• a substrate;
• a plurality of sidewalls defining a plurality of openings partially through the substrate;
• spaced-apart piezoelectric elements on the substrate, wherein each spaced-apart piezoelectric element is positioned over one of the plurality of openings;
• pairs of spaced-apart bottom electrodes on the substrate, wherein each pair of spaced-apart bottom electrodes are in contact with each of the spaced-apart piezoelectric elements;
• a conformal conductive film on each of the sidewalls of the plurality of openings, each conformal conductive film in electrical interconnection with the bottom electrodes through the substrate, wherein open cavities are maintained in each of the openings.

An ultrasound imaging probe comprising:

• a housing having a distal end;
• a piezoelectric ultrasound transducer positioned within the housing proximal to the distal end, the transducer comprising:
• a substrate;
• a plurality of sidewalls defining a plurality of openings partially through the substrate;
• spaced-apart piezoelectric elements on the substrate, wherein each spaced-apart piezoelectric element is positioned over one of the plurality of openings;
• pairs of spaced-apart bottom electrodes on the substrate, wherein each pair of spaced-apart bottom electrodes are in contact with each of the spaced-apart piezoelectric elements;
• a conformal insulating film on each of the sidewalls of the plurality of openings;
• a conformal conductive film on each of the sidewalls of the plurality of openings, each conformal conductive film in electrical interconnection with the bottom electrode through the substrate, wherein open cavities are maintained in each of the openings;
• a ground pad on the substrate;
• a second dielectric film between the piezoelectric elements;
• a top electrode in contact with the piezoelectric elements and the ground pad;
• and
• a semiconductor device attached to the ultrasonic transducer, wherein the conformal conductive film is electrically connected to the semiconductor device.

A piezoelectric ultrasound transducer comprising:

• a substrate;
• a plurality of sidewalls defining a plurality of openings partially through the substrate;
• spaced-apart piezoelectric elements on the substrate, wherein each spaced-apart piezoelectric element is positioned over one of the plurality of openings;
• pairs of spaced-apart bottom electrodes on the substrate, wherein each pair of spaced-apart bottom electrodes are in contact with each of the spaced-apart piezoelectric elements;
• a conformal conductive film on each of the sidewalls of the plurality of openings, each conformal conductive film in electrical interconnection with the bottom electrodes through the substrate, wherein open cavities are maintained in each of the openings.

A piezoelectric ultrasound transducer comprising:

• a substrate;
• a plurality of sidewalls defining a plurality of openings partially through the substrate;
• spaced-apart piezoelectric elements on the substrate, wherein each spaced-apart piezoelectric element is positioned over one of the plurality of openings;
• pairs of spaced-apart bottom electrodes on the substrate, wherein each pair of spaced-apart bottom electrodes are in contact with each of the spaced-apart piezoelectric elements;
• a conformal insulating film on each of the sidewalls of the plurality of openings;
• a conformal conductive film on each of the sidewalls of the plurality of openings, each conformal conductive film in electrical interconnection with the bottom electrode through the substrate, wherein open cavities are maintained in each of the openings;
• a ground pad on the substrate;
• a second dielectric film between the piezoelectric elements;
• a top electrode in contact with the piezoelectric elements and the ground pad;
• and
• a semiconductor device attached to the ultrasonic transducer, wherein the conformal conductive film is electrically connected to the semiconductor device.

A method of generating enhanced receive signals of a flex mode transducer, the method comprising:

• providing a piezoelectric ultrasound transducer, the piezoelectric ultrasound transducer comprising a piezoelectric element operable in flexural mode and having a ferroelectric coercive voltage;
• applying a transmit voltage sine wave signal, wherein the transmit voltage sine wave signal is greater than the ferroelectric coercive voltage;
• generating an acoustic signal as a result of the applied transmit voltage sine wave signal, the acoustic signal providing an acoustic echo;
• receiving the acoustic echo by the piezoelectric element and converting the acoustic echo to an electrical voltage by flexural mode resonance of the piezoelectric element;
• generating an enhanced receive signal wherein the enhanced receive signal generated by the piezoelectric transducer is greater than a receive signal generated by the piezoelectric transducer in the absence of a transmit voltage sine wave signal.