Imaging devices having piezoelectric transceivers
A micromachined ultrasonic transducer (MUT). The MUT includes: a substrate; a membrane suspending from the substrate; a bottom electrode disposed on the membrane; a piezoelectric layer disposed on the bottom electrode and an asymmetric top electrode is disposed on the piezoelectric layer. The areal density distribution of the asymmetric electrode along an axis has a plurality of local maxima, wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency is located.
1. A micromachined ultrasonic transducer (MUT), comprising: an electrode that is symmetric with respect to a first axis and asymmetric with respect to a second axis that is normal to the first axis, the first axis extending along a direction where the electrode has a longest dimension, the second axis passing through a midpoint between two ends of the electrode on the first axis, wherein an areal density distribution of the electrode along an axis has a plurality of local maxima, and wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency are located.
2. The MUT of claim 1 , wherein the MUT is a capacitive micromachined ultrasound transducer (cMUT).
3. The MUT of claim 1 , wherein the MUT is a piezoelectric micromachined ultrasound transducer (pMUT).
4. The MUT of claim 3 , further comprising:
a substrate;
a membrane suspending from the substrate;
a bottom electrode disposed on the membrane; and
a piezoelectric layer disposed on the bottom electrode;
wherein the electrode is disposed on the piezoelectric layer.
5. The MUT of claim 4 , wherein the piezoelectric layer is formed of at least one of PZT, KNN, PZT-N, PMN—Pt, AIN, Sc—AIN, ZnO, PVDF, and LiNiO 3 .
6. A micromachined ultrasonic transducer (MUT), comprising:
a symmetric electrode,
wherein an areal density distribution of the symmetric electrode along an axis has a plurality of local maxima and wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency are located.
7. The MUT of claim 6 , wherein the axis extends along a direction where the symmetric electrode has a longest dimension.
8. The MUT of claim 6 , wherein the vibrational resonance frequency has a symmetric vibrational mode.
9. The MUT of claim 6 , wherein the MUT is a capacitive micromachined ultrasound transducer (cMUT).
10. The MUT of claim 6 , wherein the MUT is a piezoelectric micromachined ultrasound transducer (pMUT).
11. The MUT of claim 10 , further comprising:
a substrate;
a membrane suspending from the substrate;
a bottom electrode disposed on the membrane;
a piezoelectric layer disposed on the bottom electrode; and
a top electrode disposed on the piezoelectric layer, wherein the top electrode is the symmetric electrode.
12. The MUT of claim 11 , wherein the piezoelectric layer is formed of at least one of PZT, KNN, PZT-N, PMN—Pt, AIN, Sc—AIN, ZnO, PVDF, and LiNiO 3 .
13. An imaging device, comprising:
a transducer array including a plurality of micromachined ultrasonic transducers (MUTs),
each of the plurality of MUTs comprising:
an electrode that is symmetric with respect to a first axis and asymmetric with respect to a second axis that is normal to the first axis, the first axis extending along a direction where the electrode has a longest dimension, the second axis passing through a midpoint between two ends of the electrode on the first axis, wherein an areal density distribution of the electrode along an axis has a plurality of local maxima, and wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency are located.
14. The imaging device of claim 13 , wherein each of the plurality of MUTs is a capacitive micromachined ultrasound transducer (cMUT).
15. The imaging device of claim 13 , wherein each of the plurality of MUTs is a piezoelectric micromachined ultrasound transducer (pMUT).
16. The imaging device of claim 15 , wherein each of the plurality of MUTs further comprises:
a substrate;
a membrane suspending from the substrate;
a bottom electrode disposed on the membrane; and
a piezoelectric layer disposed on the bottom electrode,
wherein the electrode is disposed on the piezoelectric layer.
17. The imaging device of claim 15 , wherein the piezoelectric layer is formed of at least one of PZT, KNN, PZT-N, PMN—Pt, AIN, Sc—AlN, ZnO, PVDF, and LiNiO 3 .
18. An imaging device, comprising:
a transducer array including a plurality of micromachined ultrasonic transducers (MUTs),
each of the plurality of MUTs comprising:
a symmetric electrode,
wherein an areal density distribution of the symmetric electrode along an axis has a plurality of local maxima and wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency are located.
19. The imaging device of claim 18 , wherein the vibrational resonance frequency has a symmetric vibrational mode.
20. The imaging device of claim 18 , wherein each of the plurality of MUTs is a capacitive micromachined ultrasound transducer (cMUT).
21. The imaging device of claim 18 , wherein each of the plurality of MUTs is a piezoelectric micromachined ultrasound transducer (pMUT).
22. The imaging device of claim 21 , wherein each of the plurality of MUTs further comprises:
a substrate;
a membrane suspending from the substrate;
a bottom electrode disposed on the membrane;
a piezoelectric layer disposed on the bottom electrode; and
a top electrode disposed on the piezoelectric layer,
wherein the top electrode is the symmetric electrode.
23. The imaging device of claim 21 , wherein the piezoelectric layer is formed of at least one of PZT, KNN, PZT-N, PMN—Pt, AIN, Sc—AIN, ZnO, PVDF, and LiNiO 3 .