Compact, energy-efficient ultrasound imaging probes using CMUT arrays with integrated electronics

Patent metadata

Field	Value
Publication number	US-9310485-B2
Application number	US-201213471426-A
Country	US
Kind code	B2
Filing date	May 14, 2012
Priority date	May 12, 2011
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A CMUT on CMOS imaging chip is disclosed. The imaging chip can use direct connection, CMOS architecture to minimize external connections and minimize chip cross-section. The CMOS architecture can enable substantially the entire chip area to be utilized for element placement. The chip can utilize arbitrarily selected transmit (Tx) and receive (Rx) element arrays to improve image quality, while reducing sampling time. The chip can comprise a plurality of dummy elements dispersed throughout the Tx and Rx elements to reduce cross-talk. The chip can utilize batch firing techniques to increase transmit power using sparse Tx arrays. The chip can comprise hexagonal Tx and or Rx subarrays for improved image quality with reduce sample sizes. The chip can utilize electrode geometry, bias voltage, and polarity to create phased and amplitude apodized arrays of Tx and Rx elements.

First claim

What is claimed is:

1. A CMUT on CMOS chip for imaging applications comprising:
a CMOS chip comprising a CMUT array comprising:
a plurality of CMUT transmit (“Tx”) elements;
a plurality of CMUT receive (“Rx”) elements; and
a plurality of dummy CMUT (“Cx”) elements to reduce cross-talk between the plurality of CMUT transmit elements and the plurality of CMUT receive elements; wherein the Cx elements comprise solid CMUT elements.

2. The CMUT on CMOS chip of claim 1 , wherein the CMUT on CMOS chip is connected to one or more outputs disposed proximate the back side of the chip with flex tape.

3. The CMUT on CMOS chip of claim 1 , wherein at least a portion of the plurality of CMUT Tx elements are disposed in two or more concentric rings to form a defocused annular array.

4. A CMUT on CMOS chip for imaging applications comprising:
a CMOS chip comprising:
a plurality of CMUT transmit (“Tx”) elements; and
a plurality of CMUT receive (“Rx”) elements;

wherein the Tx elements are disposed in a first, substantially hexagonal, array on the CMOS chip;
wherein the Rx elements are disposed in a second, substantially hexagonal, array on the CMOS chip;
wherein the first array comprises:
k central CMUT Tx elements; and
6 k peripheral CMUT Tx elements;
wherein k≧1 and an integer; and
wherein the peripheral CMUT Tx elements are disposed in a substantially hexagonal array around the central CMUT Tx elements;

wherein the central CMUT Tx elements each comprise a central element electrode;
wherein the peripheral CMUT Tx elements each comprise a peripheral element electrode; and
wherein the central elements electrode(s) are connected to a first circuit and the peripheral element electrode(s) are connected to a second circuit to create a phase shift, a difference in amplitude, or both between the central CMUT Tx elements and the peripheral CMUT Tx elements.

5. The CMUT on CMOS chip of claim 4 , wherein the number of CMUT elements in the first and second arrays is a multiple of 6.

6. The CMUT on CMOS chip of claim 4 , wherein the first array is disposed concentrically inside the second array.

7. The CMUT on CMOS chip of claim 4 , wherein the second array is disposed concentrically inside the first array.

8. The CMUT on CMOS chip of claim 4 , wherein two or more of the Tx elements in the first array can be batch fired to increase the transmit power of the first array.

9. The CMUT on CMOS chip of claim 4 , wherein at least a portion of the plurality of CMUT elements in the hexagonal Tx array are disposed in two or more concentric rings to form a defocused annular array.

10. The CMUT on CMOS chip of claim 4 , wherein the central elements electrode(s) are larger than the peripheral element electrode(s).

11. The CMUT on CMOS chip of claim 4 , wherein the Tx element electrodes each comprise dual electrodes.

12. The CMUT on CMOS chip of claim 4 ,
wherein the Tx element electrodes are sized and shaped to substantially cover the Tx elements; and
wherein the Rx elements electrodes are sized and shaped to cover between approximately 50%-80% of the Rx elements.

13. A method comprising:
selecting a subset from an array of transmit (“Tx”) elements and receive (“Rx”) elements of a CMUT array on a CMOS chip to reduce a number of element firings for imaging, the CMUT array comprising:
a plurality of CMUT transmit (“Tx”) elements; and
a plurality of CMUT receive (“Rx”) elements;

wherein selecting the subset comprises:
determining a portion of Tx elements of the plurality of CMUT Tx elements and a portion of Rx elements of the plurality of CMUT Rx elements that uniformly fill an available coarray space, while eliminating redundant Tx elements and Rx elements that do not improve imaging resolution of the CMUT array on the CMOS chip.

14. The method of claim 13 , wherein the determining is computed by synthetic array processing.

15. The method of claim 13 , wherein the determining is computed by simulated annealing.

16. The method of claim 13 , wherein the determining is computed with a point spread function.

17. The method of claim 16 , wherein computing the point spread function comprises minimizing an energy function associated with a peak side lobe level.

18. The method of claim 16 , wherein the point spread function is represented by:

H
⁡

(

r
,
θ
,
φ

)

=

∑
i

⁢

w
i

·

∑
j

⁢

w
j

·

s
⁡

(

2
⁢

⁢
r

c

-

t
i

-

t
j

-

τ
i

-

τ
j

)

wherein:
(r,θ,φ) are the spherical coordinates;
i and j represent Tx element and Rx element indices respectively;
s(.) is an excitation pulse;
c is the speed of sound;
t i and t j are flight times between a point target and the Tx and Rx elements respectively;
τ i and τ j are corresponding focusing delay times; and
w i and w j represent weighting coefficients.

19. The method of claim 18 , wherein the weighting coefficients w i and w j are set to unity.

20. The method of claim 18 , wherein one or more of obliquity and attenuation effects associated with the Tx element and Rx element are ignored.

Assignees

• Degertekin F Levent
• Karaman Mustafa
• Georgia Tech Res Inst

Inventors

• Degertekin F Levent
• Karaman Mustafa

Classifications

• G01S15/8993

  Three dimensional imaging systems · CPC title

• A61B8/4488

  the transducer being a phased array · CPC title

• G01S15/8927

  using simultaneously or sequentially two or more subarrays or subapertures · CPC title

• G01S7/5208

  with integration of processing functions inside probe or scanhead · CPC title

• A61B8/12

  in body cavities or body tracts, e.g. by using catheters · CPC title