Integrated Flexible Sensor for Blood Pressure Measurements

Patent metadata

Field	Value
Publication number	US-2022015652-A1
Application number	US-202016928933-A
Country	US
Kind code	A1
Filing date	Jul 14, 2020
Priority date	Jul 14, 2020
Publication date	Jan 20, 2022
Grant date	—

Abstract

Embodiments are directed to a blood pressure measurement device including a cuff that is operative to wrap around a limb of a user, a bladder coupled to the cuff and operative to compress the limb of the user when inflated, and a piezoelectric sensor coupled to the cuff and operative to detect blood flow through the limb of the user and output a signal indicative of the blood flow. The blood pressure measurement device can also include a processor coupled with the piezoelectric sensor that is operative to filter the signal to isolate sounds corresponding to changes in the blood flow through the limb due to inflation of the bladder, correlate the isolated sounds with a pressure inside the bladder, and determine a blood pressure of the user at least partially based on correlating the isolated sounds with the pressure.

First claim

What is claimed is:

1 . A blood pressure measurement device comprising:
a cuff operative to wrap around a limb of a user; a bladder coupled to the cuff and operative to compress the limb of the user when inflated; a piezoelectric sensor coupled to the cuff and operative to:
detect blood flow through the limb of the user; and
output a signal indicative of the blood flow; and
a processor coupled with the piezoelectric sensor and operative to:
filter the signal to isolate sounds corresponding to changes in the blood flow through the limb due to inflation of the bladder;
correlate the isolated sounds with a pressure inside the bladder; and
determine a blood pressure of the user at least partially based on correlating the isolated sounds with the pressure.

2 . The blood pressure measurement device of claim 1 , further comprising a pressure sensor, wherein:
the signal is a first signal; the pressure sensor is operative to measure the pressure inside the bladder and output a second signal indicating the pressure to the processor; the cuff comprises an upper edge and a lower edge; the bladder is positioned between the upper edge and the piezoelectric sensor; the piezoelectric sensor is positioned between the cuff and the limb; and filtering the first signal to isolate the sounds comprises identifying:
a first sound indicative of restriction of the blood flow due to partial collapse of a blood vessel within the limb; and
a second sound indicative of stoppage of the blood flow in the blood vessel.

3 . The blood pressure measurement device of claim 1 , wherein filtering the signal comprises:
applying a first band pass filter having a first frequency range to the signal; applying a second band pass filter having a second frequency range to the signal; and the first frequency range comprises higher frequency components of the signal than the second frequency range.

4 . The blood pressure measurement device of claim 3 , wherein:
the first frequency range comprises frequency components that correspond to the sounds resulting due to the changes in the blood flow.

5 . The blood pressure measurement device of claim 1 , further comprising a pump operative to inflate the bladder, wherein:
the piezoelectric sensor is operative to detect changes in sounds corresponding to blood flow within a frequency range; and the pump operates at a frequency that is greater than the frequency range.

6 . The blood pressure measurement device of claim 5 , wherein the pump is an ultrasonic pump.

7 . The blood pressure measurement device of claim 1 , wherein the piezoelectric sensor is operative to wrap around a substantial entirety of the limb.

8 . The blood pressure measurement device of claim 1 , wherein the piezoelectric sensor is a differential piezoelectric sensor.

9 . The blood pressure measurement device of claim 1 , wherein the piezoelectric sensor is positioned within an interior portion of the cuff.

10 . A blood pressure measurement device, comprising:
a cuff operative to wrap around a limb of a user; a bladder coupled to the cuff and operative to compress the limb of the user when inflated; a piezoelectric sensor coupled to the cuff, and operative to detect blood flow through the limb of the user; and a processor operative to:
receive a signal from the piezoelectric sensor that is indicative of the blood flow through the limb; and
filter the signal to:
identify a first sound that corresponds to a change in the blood flow due to a partial collapse of a blood vessel within the limb; and
identify a second sound that corresponds to a stoppage of the blood flow in the blood vessel within the limb; and

determine a blood pressure of the user at least partially based on the identified first and second sounds.

11 . The blood pressure measurement device of claim 10 , wherein:
the cuff comprises an upper edge and a lower edge; the piezoelectric sensor is operative to wrap around the limb of the user, when the cuff is worn by the user; the piezoelectric sensor is contained within the cuff; and the piezoelectric sensor is positioned between the bladder and the lower edge.

12 . The blood pressure measurement device of claim 10 , wherein the piezoelectric sensor is positioned between the bladder and the limb when the cuff is worn by the user.

13 . The blood pressure measurement device of claim 10 , wherein:
the bladder is contained within a proximal portion of the cuff; the piezoelectric sensor is contained within a distal portion of the cuff; and the piezoelectric sensor is separated from the bladder by a dampening material that is operative to isolate the piezoelectric sensor from pressure oscillations within the bladder.

14 . The blood pressure measurement device of claim 10 , wherein:
the signal is a first signal; and the blood pressure measurement device, further comprises:
a pump coupled to the bladder and operative to inflate the bladder; and
a pressure sensor coupled to the bladder and operative to output a second signal indicative of a pressure within the bladder.

15 . The blood pressure measurement device of claim 14 , wherein the processor is operative to:
receive the second signal from the pressure sensor; determine a first pressure within the cuff that corresponds to identifying the first sound; and determine a second pressure within the cuff that corresponds to identifying the second sound.

16 . The blood pressure measurement device of claim 10 , wherein the processor is operative to determine the blood pressure of the user from signals corresponding to inflation of the bladder.

17 . A method for measuring blood pressure of a user, the method comprising:
inflating a bladder of a cuff to increase a pressure within the bladder to compress a blood vessel of the user; detecting, using a piezoelectric sensor, changes in blood flow through the blood vessel, the changes corresponding to collapse of the blood vessel; outputting a first signal indicative of the changes in the blood flow; detecting, using a pressure sensors, the pressure within the bladder; outputting a second signal indicative of the pressure; and filtering the first signal to:
identify a first sound that corresponds to a change in blood flow through the blood vessel due to partial collapse of the blood vessel; and
identify a second sound that corresponds to a stoppage of blood flow in the blood vessel;
operating a processor to:
receive the first and second signals;
determine, using the first and second signals, a first pressure in the bladder corresponding to an occurrence of the first sound;
determine, using the first and second signals, a second pressure in the bladder corresponding to an occurrence of the second sound; and
estimate a blood pressure of the user using the first pressure and the second pressure.

18 . The method of claim 17 , wherein filtering the first signal comprises:
using a first band pass filter to isolate portions of the first signal falling within a first frequency band corresponding to changes in sound of the blood flow; and using a second band pass filter to isolate portions of the first signal falling within a second frequency band corresponding to changes in the pressure within the bladder.

19 . The method of claim 18 , wherein:
the portions of the first signal falling within the first frequency band are used to determine systolic and diastolic blood pressure of the user; and the portions of the first signal falling within the s

Assignees

• Apple Inc

Inventors

• Lee Joseph R
• Schmitt Joseph M
• Young Derek
• Jain Pranay
• Amin Ali M
• Tadele Wegene
• Zeng Zijing

Classifications

• A61B5/0225 Primary

  the pressure being controlled by electric signals, e.g. derived from Korotkoff sounds · CPC title

• A61B5/72

  Signal processing specially adapted for physiological signals or for diagnostic purposes · CPC title

• A61B5/02141

  Details of apparatus construction, e.g. pump units or housings therefor, cuff pressurising systems, arrangements of fluid conduits or circuits (A61B5/02233, A61B5/0235 take precedence) · CPC title

• A61B5/02208

  using the Korotkoff method · CPC title

• A61B5/6824

  Arm or wrist · CPC title