System and method for non-invasively sensing a blood vessel

1 . A system for non-invasively sensing a blood vessel, the system comprising:

a sensor having an array of ultrasound transducers that includes at least a first ultrasound transducer and a second ultrasound transducer, the array having a first column, a first row, and a second row, the first row spaced apart from the second row by an intercolumn distance, the first ultrasound transducer disposed in the first column and the first row, and the second ultrasound transducer disposed in the first column and the second row;

wherein the first ultrasound transducer is configured to produce first ultrasonic signals at a first wavelength, and the first ultrasound transducer has a first length that extends along a first lengthwise axis and the first length is greater than the first wavelength, and a first width that is equal to or less than the first wavelength; and

wherein the second ultrasound transducer is configured to produce second ultrasonic signals at a second wavelength, and the second ultrasound transducer has a second length that extends along a second lengthwise axis and the second length is greater than the second wavelength and a second width that is equal to or less than the second wavelength; and

wherein the first lengthwise axis of the first ultrasound transducer and the second lengthwise axis of the first ultrasound transducer are aligned with one another along a column axis of the first column; and

a controller in communication with the first ultrasound transducer and the second ultrasound transducer, and a memory storing instructions, wherein the instructions when executed cause the controller to:

control the first ultrasound transducer to produce a first beam of first ultrasonic signals and to receive reflected first ultrasonic signals, and to communicate first sensed signals to the controller that are representative of the reflected first ultrasonic signals;

control the second ultrasound transducer to produce a second beam of second ultrasonic signals and to receive reflected second ultrasonic signals, and to communicate second sensed signals to the controller that are representative of the reflected second ultrasonic signals;

determine a first vessel diameter value using the first sensed signals;

determine a second vessel diameter value using the second sensed signals; and

determine a pulse wave velocity value using the first sensed signals and the second sensed signals.

2 . The system of claim 1 , wherein the first beam of first ultrasonic signals is configured to have a first focal zone disposed at a predetermined depth, and a first width at the predetermined depth that is equal to or greater than a predetermined vessel diameter.

3 . The system of claim 2 , wherein the second beam of second ultrasonic signals is configured to have a second focal zone disposed at the predetermined depth, and a second width at the predetermined depth that is equal to or greater than the predetermined vessel diameter.

4 . The system of claim 1 , wherein the instructions when executed cause the controller to determine a first position of an anterior wall portion of the blood vessel using the first sensed signals, and determine a first position of a posterior wall portion of the blood vessel using the first sensed signals, and determine the first vessel diameter value using the determined first position of the anterior wall portion of the vessel and the determined first position of the posterior wall portion.

5 . The system of claim 4 , wherein the instructions when executed cause the controller to determine a second position of the anterior wall portion of the blood vessel using the second sensed signals, and determine a second position of the posterior wall portion of the blood vessel using the second sensed signals, and determine the second vessel diameter value using the determined second position of the anterior wall portion of the vessel and the determined second position of the posterior wall portion.

6 . The system of claim 5 , wherein the instructions when executed cause the controller to identify a pulse wave traveling past a first vessel axial position using the determined first position of the anterior wall portion of the blood vessel and the determined first position of the posterior wall portion, and to identify the pulse wave traveling past a second vessel axial position using the determined second position of the anterior wall portion of the blood vessel and the determined second position of the posterior wall portion, and to determine a period of elapsed time between the pulse wave passing the first vessel axial position and the pulse wave passing the second vessel axial position.

7 . The system of claim 6 , wherein the first vessel axial position and the second vessel axial position are separated by the intercolumn distance.

8 . The system of claim 1 , wherein the instructions when executed cause the controller to identify a pulse wave traveling past a first vessel axial position using the first sensed signals and to identify the pulse wave traveling past a second vessel axial position using the second sensed signals, and to determine a period of elapsed time between the pulse wave passing the first vessel axial position and the pulse wave passing the second vessel axial position.

9 . The system of claim 8 , wherein the first vessel axial position and the second vessel axial position are separated by the intercolumn distance.

10 . The system of claim 1 , wherein the first column is orthogonal to the first row and to the second row.

11 . A method of non-invasively sensing a blood vessel, comprising:

providing a sensor having an array of ultrasound transducers that includes at least a first ultrasound transducer and a second ultrasound transducer, the array having a first column, a first row, and a second row, the first row spaced apart from the second row by an intercolumn distance, the first ultrasound transducer disposed in the first column and the first row, and the second ultrasound transducer disposed in the first column and the second row, and a controller in communication with the first ultrasound transducer and the second ultrasound transducer;

wherein the first ultrasound transducer is configured to produce first ultrasonic signals at a first wavelength, and the first ultrasound transducer has a first length that extends along a first lengthwise axis and the first length is greater than the first wavelength, and a first width that is equal to or less than the first wavelength; and

wherein the second ultrasound transducer is configured to produce second ultrasonic signals at a second wavelength, and the second ultrasound transducer has a second length that extends along a second lengthwise axis and the second length is greater than the second wavelength and a second width that is equal to or less than the second wavelength; and

wherein the first lengthwise axis of the first ultrasound transducer and the second lengthwise axis of the second ultrasound transducer are aligned with one another along a column axis of the first column; and

disposing the sensor on a skin surface of a subject so that the column axis of the first column substantially aligns with an axial length of the blood vessel;

operating the first ultrasound transducer to interrogate the blood vessel with a first beam of first ultrasonic signals, and to receive reflected first ultrasonic signals, the first ultrasound transducer configured to produce first sensed signals representative of the reflected first ultrasonic signals;

operating the second ultrasound transducer to interrogate the blood vessel with a second beam of second ultrasonic signals, and to receive reflected second ultrasonic signals, the second ultrasound transducer configured to produce second sensed signals representative of the reflected second ultrasonic signals;

determining a first vessel diameter value using the first sensed signals;

determining a second vessel diameter value using the second sensed signals; and

determining a pulse wave velocity value using the first sensed signals and the second sensed signals.

12 . The method of claim 11 , wherein the blood vessel is an artery.

13 . The method of claim 11 , wherein the first beam of first ultrasonic signals is configured to have a first focal zone disposed at a predetermined depth, and a first width at the predetermined depth that is equal to or greater than a predetermined vessel diameter.

14 . The method of claim 13 , wherein the second beam of second ultrasonic signals is configured to have a second focal zone disposed at the predetermined depth, and a second width at the predetermined depth that is equal to or greater than the predetermined vessel diameter.

15 . The method of claim 11 , wherein the step of determining said first vessel diameter value using the first sensed signals includes determining a first position of an anterior wall portion of the blood vessel using the first sensed signals, and determining a first position of a posterior wall portion of the blood vessel using the first sensed signals, and determining the first vessel diameter value using the determined first position of the anterior wall portion of the vessel and the determined first position of the posterior wall portion.

16 . The method of claim 15 , wherein the step of determining said second vessel diameter value using the second sensed signals includes determining a second position of the anterior wall portion of the blood vessel using the second sensed signals, and determining a second position of the posterior wall portion of the blood vessel using the second sensed signals, and determining the second vessel diameter value using the determined second position of the anterior wall portion of the vessel and the determined second position of the posterior wall portion.

17 . The method of claim 16 , wherein the step of determining said pulse wave velocity value using the first sensed signals and the second sensed signals includes identifying a pulse wave traveling past a first vessel axial position using the determined first position of the anterior wall portion of the vessel and the determined first position of the posterior wall portion, and identifying the pulse wave traveling past a second vessel axial position using the determined second position of the anterior wall portion of the vessel and the determined second position of the posterior wall portion, and determining a period of elapsed time between the pulse wave passing the first vessel axial position and the pulse wave passing the second vessel axial position.

18 . The method of claim 11 , wherein the step of determining said pulse wave velocity value using the first sensed signals and the second sensed signals includes identifying a pulse wave traveling past a first vessel axial position using the first sensed signals, and identifying the pulse wave traveling past a second vessel axial position using the second sensed signals, and determining a period of elapsed time between the pulse wave passing the first vessel axial position and the pulse wave passing the second vessel axial position.

19 . The system of claim 1 , wherein the first wavelength equals the second wavelength.

20 . The system of claim 1 , wherein the array of ultrasound transducers includes a plurality of first ultrasound transducers disposed in the first row, wherein adjacent first ultrasound transducers in the first row are separated from one another by an interrow distance, and the array includes a plurality of second ultrasound transducers in the second row, wherein adjacent second ultrasound transducers in the second row are separated from one another by the interrow distance.

21 . The system of claim 1 , wherein the array of ultrasound transducers includes a third ultrasound transducer disposed in the first row separated from the first ultrasound transducer in the first row by an interrow distance, and a fourth ultrasound transducer in the second row disposed in the second row separated from the second ultrasound transducer in the second row by the interrow distance; and

wherein the third ultrasound transducer and the fourth ultrasound transducer are disposed in a second column;

wherein the third ultrasound transducer is configured to produce third ultrasonic signals at a third wavelength, and the third ultrasound transducer has a third length that extends along a third lengthwise axis and the third length is greater than the third wavelength, and a third width that is equal to or less than the third wavelength; and

wherein the fourth ultrasound transducer is configured to produce fourth ultrasonic signals at a fourth wavelength, and the fourth ultrasound transducer has a fourth length that extends along a fourth lengthwise axis and the fourth length is greater than the fourth wavelength and a fourth width that is equal to or less than the fourth wavelength; and

wherein the third lengthwise axis of the third ultrasound transducer and the fourth lengthwise axis of the fourth ultrasound transducer are aligned with one another along a column axis of the second column; and

wherein the column axis of the first column and the column axis of the second column are parallel one another.