WRIST-WORN PULSE TRANSIT TIME SENSOR

• US 20160287172A1
• Filed: 06/25/2015
• Published: 10/06/2016
• Est. Priority Date: 04/02/2015
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Cohn, Gabriel Adam, Kale, David C., Malladi, Sailaja, Morris, Daniel, Tan, Desney S., Saponas, T. Scott, Patel, Shwetak N., Villar, Nicolas, Smith, Gregory R., Gupta, Sidhant, Paulsen, Ronald E.
• Granted Patent: US 10,709,383 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/0462 Apparatus with built-in sensors
• CPC Class Codes: A61B 2560/0468 Built-in electrodes
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/0024 for multiple sensor units attached to the patient, e.g. using a body or personal area network
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/02444 Details of sensor A61B5/02427 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/1072 measuring distances on the body, e.g. measuring length, height or thickness A61B5/1076 takes precedence
• CPC Class Codes: A61B 5/1075 for measuring dimensions by non-invasive methods, e.g. for determining thickness of tissue layer A61B8/0858 takes precedence
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/282 Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6828 : Leg
• CPC Class Codes: A61B 5/6831 : Straps, bands or harnesses
• CPC Class Codes: A61B 5/7264 : Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61B 5/7278 : Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/742 : using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/7475 : User input or interface means, e.g. keyboard, pointing device, joystick
• CPC Class Codes: A61B 7/04 : Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: G16H 50/20 : for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

A wrist-worn device heart-monitoring device is presented. The wrist-worn heart-monitoring device includes a radial tonometer configured to output a pressure signal indicating a pulse pressure wave at a user'"'"'s wrist, two or more electrodes configured to output an electrical signal indicating a user'"'"'s heart has been commanded to contract, and a microphone configured to output an audio signal indicating a closing of a user'"'"'s aortic valve. The wrist-worn heart-monitoring device further includes a pulse transit time monitor configured to calculate a pre-ejection period of the user'"'"'s heart based on at least the pressure, electrical, and audio signals, and calculate a pulse transit time based on at least the pre-ejection period, the pressure signal, and the electrical signal.

Claims

1. A wrist-worn heart monitoring device, comprising:

a radial tonometer configured to output a pressure signal indicating a pulse pressure wave at a wearer'"'"'s wrist;

two or more electrodes configured to output an electrical signal indicating a wearer'"'"'s heart has been commanded to contract;

a microphone configured to output an audio signal indicating a closing of a wearer'"'"'s aortic valve; and

a pulse transit time monitor configured to;

calculate a pre-ejection period of the wearer'"'"'s heart based on at least the pressure, electrical, and audio signals; and

calculate a pulse transit time based on at least the pre-ejection period, the pressure signal, and the electrical signal.

2. The wrist-worn heart monitoring device of claim 1, wherein one or more electrodes are located on a user-adjacent surface of the wrist-worn heart monitoring device, and wherein one or more electrodes are located on an externally-facing surface of the wrist-worn heart monitoring device.

3. The wrist-worn heart monitoring device of claim 1, further comprising:

a primary device;

a satellite device including the radial tonometer; and

an adjustable strap configured to fix a position of the satellite device relative to the primary device, the primary device, satellite device, and adjustable strap cooperatively forming a loop configured to be worn around the wearer'"'"'s wrist.

4. The wrist-worn heart monitoring device of claim 3, wherein the radial tonometer further comprises:

a flexible cap configured to at least partially protrude from an opening in a housing of the satellite device, and further configured to conduct pressure to a pressure transducer within the satellite device.

5. The wrist-worn heart monitoring device of claim 3, wherein one or more of the electrodes located on the externally-facing surface of the wrist-worn heart monitoring device are located at the adjustable strap.

6. The wrist-worn heart monitoring device of claim 1, wherein the electrical signal indicating a wearer'"'"'s heart has been commanded to contract is output responsive to a sensed heartbeat command while first electrode contacts a first measurement location on a wearer'"'"'s skin on a first effective side of the wearer'"'"'s heart, and a second electrode contacts a second measurement location on the wearer'"'"'s skin on a second, opposite, effective side of the wearer'"'"'s heart.

7. The wrist-worn heart monitoring device of claim 1, wherein the pulse transit time monitor is further configured to:

calculate a pulse wave velocity based on the pulse transit time and a distance between the wearer'"'"'s aortic valve and the wearer'"'"'s wrist.

8. The wrist-worn heart monitoring device of claim 1, wherein the pulse transit time monitor is further configured to:

store the calculated pre-ejection period of the wearer'"'"'s heart; and

calculate a radial pulse arrival time responsive to receiving an electrical signal indicating the wearer'"'"'s heart has been commanded to contract, and a pressure signal indicating a pulse pressure wave at the wearer'"'"'s wrist;

calculate a pulse-transit time based on at least the radial pulse arrival time and the stored pre-ejection period without receiving an audio signal indicating a closing of the wearer'"'"'s aortic valve.

9. A wrist-worn heart monitoring device, comprising:

a primary device;

an adjustable strap, the primary device and adjustable strap cooperatively forming a loop configured to be worn around a wearer'"'"'s wrist, the loop having an inner surface facing the wearer'"'"'s wrist and an outer surface facing away from the wearer'"'"'s wrist;

a first electrode on the inner surface of the loop and configured to contact a first measurement location on a wearer'"'"'s skin on a first effective side of the wearer'"'"'s heart;

a second electrode on the outer surface of the loop at the adjustable strap and configured to contact a second measurement location on the wearer'"'"'s skin on a second, opposite, effective side of the wearer'"'"'s heart; and

a controller configured to measure an electrical potential between the first measurement location and the second measurement location.

10. The wrist-worn heart monitoring device of claim 9, wherein the first electrode is in contact with an underside of the wearer'"'"'s wrist when the primary device is located on a back of the wearer'"'"'s wrist.

11. The wrist-worn heart monitoring device of claim 9, wherein the adjustable strap comprises one or more conductive zones on an outer surface of the adjustable strap, and wherein the second electrode is included in a conductive zone on the outer surface of the adjustable strap.

12. The wrist-worn heart monitoring device of claim 11, wherein the adjustable strap comprises one or more conductive zones on an inner surface of the adjustable strap, and wherein the first electrode is included in a conductive zone on the inner surface of the adjustable strap.

13. The wrist-worn heart monitoring device of claim 9, further comprising:

a third electrode on the outer surface of the loop and configured to contact a third measurement location on the wearer'"'"'s skin.

14. The wrist-worn heart monitoring device of claim 13, further comprising:

fastening componentry configured to adjust a circumference of the loop through interactions with the adjustable strap and including one or more conductive components electrically coupled to the primary device such that the third electrode comprises the one or more conductive components of the fastening componentry.

15. The wrist-worn heart monitoring device of claim 13, wherein the controller is further configured to determine a composite negative pole of the wearer based on the electrical potential between the first measurement location and the second measurement location, an electrical potential between the first measurement location and the third measurement location, and an electrical potential between the second measurement location and the third measurement location.

16. A wrist-worn heart monitoring device, comprising:

a first electrode and a second electrode, the first and second electrodes configured to output a voltage difference indicative of an electrical potential of a wearer'"'"'s heart when the first electrode contacts a first measurement location on a wearer'"'"'s skin on a first effective side of the wearer'"'"'s heart and the second electrode contacts a second measurement location on the wearer'"'"'s skin on a second, opposite, effective side of the wearer'"'"'s heart;

an electrode-positioning sensor subsystem to determine a three-dimensional position of the second electrode respective to the second measurement location; and

a controller configured to;

receive a voltage difference from the first and second electrodes;

receive an indication of the three-dimensional position of the second electrode respective to the second measurement location from the electrode-positioning sensor subsystem; and

output an electrical potential of the wearer'"'"'s heart responsive to the second electrode being located within a threshold distance of the second measurement location.

17. The wrist-worn heart monitoring device of claim 16, further comprising a user interface configured to:

communicate an instruction to adjust the three-dimensional position of the second electrode responsive to the second electrode being located more than the threshold distance from the second measurement location

18. The wrist-worn heart monitoring device of claim 17, wherein the electrode-positioning sensor subsystem is further configured to determine a three-dimensional position of the second electrode respective to one or more additional measurement locations, and wherein the user interface is further configured to:

communicate an instruction to adjust the three-dimensional position of the second electrode from the second measurement location to a third measurement location.

19. The wrist-worn heart monitoring device of claim 18, wherein the controller is further configured to:

receive an indication of the three-dimensional position of the second electrode respective to the third measurement location from the electrode-positioning sensor subsystem; and

output the electrical potential of the user'"'"'s heart responsive to the second electrode being located within the threshold distance of the third measurement location.

20. The wrist-worn heart monitoring device of claim 17, wherein the electrode-positioning sensor subsystem is configured to receive signals from one or more motion sensors included in the wrist-worn heart monitoring device, and from one or more cameras.