Multilayer ultrasound transducer devices for high power transmission and wide-band reception and associated systems and methods

1. An ultrasound device, comprising:

a first array of first transducers, the first transducers oriented along an acoustic axis and comprising a first piezoelectric material configured to transmit nonlinear acoustic waves;

a second array of second transducers oriented along the acoustic axis and substantially parallel to the first transducers, the second transducers comprising a second piezoelectric material configured to receive echoes from the acoustic waves, wherein the acoustic waves have a fundamental frequency, and wherein the second transducers are configured to sense up to at least a third harmonic of the fundamental frequency; and

an electrical connection layer between the first and second arrays and electrically coupled to the first and second transducers, wherein the electrical connection layer comprises first channels electrically coupled to the first transducers and second channels electrically coupled to the second transducers and electrically isolated from the first transducers.

2. The ultrasound device of claim 1 wherein:

the first transducers are substantially co-aligned with corresponding second transducers;

the first piezoelectric material comprises lead zirconate titanate;

the second piezoelectric material comprises polyvinylidene fluoride having a thickness of less than approximately 110 μm; and

the ultrasound device further comprises:

an aperture over the first and second transducers, the second transducers being proximate to the aperture, wherein the acoustic waves are configured to exit the ultrasound device via the aperture and the echoes from the acoustic waves are configured to enter the ultrasound device via the aperture;

a backing layer on a back surface of the first transducers, the backing layer being configured to enhance radiation forward of the first transducers;

a first impedance matching layer over the first transducers; and

a second impedance matching layer over the second transducers.

3. The ultrasound device of claim 1 , further comprising an aperture over the first and second transducers, wherein the acoustic waves are configured to exit the ultrasound device via the aperture and the echoes from the acoustic waves are configured to enter the ultrasound device via the aperture.

4. The ultrasound device of claim 1 wherein:

the first piezoelectric material comprises lead zirconate titanate; and

the second piezoelectric material comprises polyvinylidene fluoride.

5. The ultrasound device of claim 1 wherein:

the first piezoelectric material is configured to transmit higher power acoustic waves than the second piezoelectric material; and

the second piezoelectric material is configured to receive a wider bandwidth of echoes than the first piezoelectric material.

6. The ultrasound device of claim 1 wherein the ultrasound device is configured to transmit high intensity ultrasound waves.

7. The ultrasound device of claim 1 wherein:

the ultrasound device has a fundamental frequency having a wavelength; and

the second transducers and the electrical connection layer have a combined thickness that is a fraction of the wavelength of the fundamental frequency.

8. The ultrasound device of claim 1 , further comprising a damping layer between the first and second transducers, wherein the damping layer is configured to decrease reverberations of the acoustic waves between the first and second transducers and smooth frequency response of the second transducers.

9. The ultrasound device of claim 1 wherein the electrical connection layer comprises a flex circuit having a thickness such that the electrical connection layer is substantially acoustically transparent to a frequency of less than approximately 5 MHz.

10. The ultrasound device of claim 1 , further comprising an amplifier operably coupled to and positioned proximate to the second transducer.

11. An ultrasound device, comprising:

a first transducer having a first side opposite a second side, the first transducer comprising a piezoceramic material;

a second transducer having a first side opposite a second side, the second transducer comprising a piezopolymer material, wherein the first and second transducers are stacked such that the second sides face one another;

a flex circuit between the first and second transducers and operably coupled to the first and second transducers, wherein the flex circuit comprises first channels electrically coupled to the first transducer and second channels electrically coupled to the second transducer and electrically isolated from the first transducers; and

an aperture proximate to the first side of the second transducer, wherein the first transducer is configured to transmit acoustic waves through the aperture that become nonlinear through propagation and the second transducer is configured to receive echoes from the acoustic waves through the aperture, and wherein the second transducer detects up to at least a third harmonic in the echo.

12. The ultrasound device of claim 11 , further comprising:

a backing layer at the first side of the first transducer; and

an impedance matching layer over the second side of the first transducer.

13. The ultrasound device of claim 11 wherein the second transducer has a thickness of less than approximately 110 μm.

14. The ultrasound device of claim 11 wherein the second transducer has bandwidth of at least approximately 20 MHz.

15. The ultrasound device of claim 11 wherein the flex circuit has a thickness of less than approximately 50 μm.

16. The ultrasound device of claim 11 wherein:

the first transducer is one of a plurality of first transducers arranged in a first array; and

the second transducer is one of a plurality of second transducers arranged in a second array over the first array.

17. The ultrasound device of claim 11 , further comprising an elastomeric layer between the first and second transducers.

18. A method of performing an ultrasound scan, the method comprising:

transmitting acoustic waves with a first array of first transducers, the first transducers comprising a piezoceramic material;

propagating the acoustic waves through an aperture toward a medium, wherein the acoustic waves become nonlinear through propagation;

detecting echoes from the acoustic waves with a second array of second transducers via the aperture, the second transducers comprising a piezopolymer material, wherein the first and second transducers are oriented substantially parallel to one another along an acoustic axis with an electrical connection layer between the first and second transducers, wherein the electrical connection layer comprises first channels electrically coupled to the first transducers and second channels electrically coupled to the second transducers and electrically isolated from the first transducers; and

sensing up to at least a third harmonic in the detected echoes with the second transducers.

19. The method of claim 18 , further comprising:

damping reverberations of the acoustic waves between the first and second transducers with an elastomeric material; and

smoothing a frequency response of the second transducers with the elastomeric material.

20. The method of claim 18 wherein:

transmitting acoustic waves comprises propagating the acoustic waves toward a tissue, the acoustic waves having a fundamental frequency; and

the method further comprises measuring attenuation in the sensed harmonics to determine a temperature in the tissue.

21. The method of claim 18 wherein:

transmitting acoustic waves comprises transmitting therapeutic ultrasound waves toward a tissue; and

the method further comprises monitoring at least one of temperature and temperature sensitive characteristics in the tissue during transmission of therapeutic waves by detecting harmonic scattering beyond a second harmonic of a fundamental frequency.

22. An ultrasound device, comprising:

a first array of first transducers, wherein the individual first transducers are oriented along an acoustic axis, and wherein the first transducers are configured to transmit ultrasound waves that become nonlinear through propagation;

a second array of second transducers substantially aligned with the first transducers along the acoustic axis, wherein the second transducers are configured to detect echo data including up to at least the third harmonic of the nonlinear ultrasound waves transmitted by the first transducers, and wherein the first transducers comprise a different transducer material than the second transducers; and

an electrical connection layer between the first and second arrays, wherein the electrical connection layer comprises first channels electrically coupled to the first transducers and second channels electrically coupled to the second transducers and electrically isolated from the first transducers.