DUAL-FREQUENCY ULTRASOUND TRANSDUCER

• US 20120267986A1
• Filed: 06/17/2010
• Published: 10/25/2012
• Est. Priority Date: 06/19/2009
• Status: Active Grant

• Current Assignee: CareWear Corp.
• Original Assignee: Sonovia Holdings LLC
• Inventors: Galluzzo, Paul Mark, Buckland, Justine Rorke, Pollock, Neil
• Granted Patent: US 9,108,221 B2
• Time in Patent Office: Days
• US Class Current: 310/348
• CPC Class Codes: B06B 1/0603 using a piezoelectric bender, e.g. bimorph
• CPC Class Codes: Y10T 29/49005 Acoustic transducer

Abstract

A dual-frequency ultrasound transducer, comprising a piezo-electric element bonded to a substrate, has two resonant vibration modes: a low frequency mechanical bending resonance mode and a relatively high frequency thickness resonance mode. The low frequency bending resonance mode occurs when the piezo-electric element is excited, in use, by a voltage which includes a low frequency oscillating component. The high frequency thickness resonance mode occurs when the piezo-electric element is excited, in use, by a voltage which includes a relatively high frequency oscillating component. The transducer may include a mounting arrangement, such as a support ring securing the periphery of the substrate to an underlying base layer that enhances the depth of penetration and focus of the ultrasound.

Claims

1. A dual-frequency ultrasound transducer, comprising:

a substrate; and

a piezo-electric element bonded to the substrate;

wherein the transducer has a low frequency mechanical bending resonance mode when the piezo-electric element is excited, in use, by a voltage which includes a low frequency oscillating component; and

wherein the transducer has a relatively high frequency thickness resonance mode when the piezo-electric element is excited, in use, by a voltage which includes a relatively high frequency oscillating component.

2. The transducer of claim 1, wherein the piezo-electric element is recessed in from the edge of the substrate.

3. The transducer of claim 1, wherein the piezo-electric element is a planar disc.

4. The transducer of claim 3, wherein the substrate is a planar disc.

5. The transducer of claim 1, further comprising a base layer on which the substrate is supported, the outer edge of the substrate being bent away and out of contact from the base layer.

6. The transducer of claim 1, in which the peripheral edge of the substrate is clamped between a support structure and a base layer.

7. The transducer of claim 6, wherein the support structure includes an inward facing recess into which the peripheral edge of the substrate is received, such that the interface between the support structure and the substrate comprises a quasi built-in support.

8. The transducer of claim 6, wherein the support structure includes a pointed bottom surface, such that the interface between the support structure and the substrate comprises a quasi pin joint.

9. The transducer of claim 1, wherein the substrate is profiled to form a recess in which the peizo-electric element is received.

10. The transducer of claim 1, wherein the substrate is metal.

11. A patch comprising a plurality of the transducers of claim 1 arranged in an array.

12. A method of manufacturing a dual-frequency ultrasound transducer, comprising:

bonding a piezo-electric element to a substrate;

wherein the piezo-electric element and substrate are selected to have a combined thickness corresponding to odd numbers of half a desired high frequency resonant wavelength; and

wherein the diameters of the piezo-electric element and the substrate are determined on the basis of the selected thicknesses and a desired low frequency resonant frequency.

13. The method of claim 12, wherein the diameters are determined as at least 5 times the combined thickness of the substrate and piezo-element.

14. The method of claim 12, further comprising selecting a material of the substrate so as to maximize performance of the transducer at the desired low frequency resonant frequency

15. The method of claim 12, further comprising selecting a material for each of the substrate and transducer and thicknesses according to the equation:

Y₁h₁²=Y₂h₂²,

where Y₁ is the stiffness of the peizo-electric element, Y₂ is the stiffness of the substrate, h₁ is the thickness of the peizo-electric element and h₂ is the thickness of the substrate.