Transducing pressure to a non-invasive pulse sensor

Patent metadata

Field	Value
Publication number	US-2016287102-A1
Application number	US-201514750747-A
Country	US
Kind code	A1
Filing date	Jun 25, 2015
Priority date	Apr 2, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

A system for transducing arterial pressure includes a one-piece flexible cap configured to fit around a flexible piezo-electric sensor that is configured to alter an internal resistance upon deflection. The flexible cap includes a deflection wall configured to deflect towards the flexible piezo-resistive sensor in proportion to pressure applied by the artery. A pressure-transducing medium is sealed between the one-piece flexible cap and the flexible piezo-resistive sensor, such that deflection of the deflection wall towards the flexible piezo-resistive sensor causes proportional deflection of the flexible piezo-resistive sensor.

First claim

1 . A system for transducing arterial pressure, comprising:
a flexible piezo-resistive sensor configured to alter an internal resistance as a function of deflection of the flexible piezo-resistive sensor; a one-piece flexible cap including:
a sidewall sized to fit around the flexible piezo-resistive sensor, and
a deflection wall capping the sidewall and shaped to conform between a radius and a flexor carpi radialis tendon, the deflection wall configured to deflect towards the flexible piezo-resistive sensor in proportion to pressure applied by a radial artery; and
a pressure-transducing medium sealed between the one-piece flexible cap and the flexible piezo-resistive sensor such that deflection of the deflection wall towards the flexible piezo-resistive sensor causes proportional deflection of the flexible piezo-resistive sensor.

2 . The system of claim 1 , wherein the deflection wall includes a spring region between a user-interfacing portion of the deflection wall and the sidewall, the spring region biasing the deflection wall at a maximum distance from the flexible piezo-resistive sensor when no pressure is applied to the user-interfacing portion.

3 . The system of claim 2 , wherein the user-interfacing portion is perpendicular to the sidewall.

4 . The system of claim 2 , wherein the spring region is angled with respect to the flexible piezo-resistive sensor and decreases in diameter from the sidewall to the user-interfacing portion.

5 . The system of claim 2 , wherein the user-interfacing portion has a greater thickness than the spring region.

6 . The system of claim 2 , wherein the flexible piezo-resistive sensor is affixed to a substrate, and wherein the system further comprises:
an open-ended rigid conduit affixed to the substrate surrounding the flexible piezo-resistive sensor, the open-ended rigid conduit configured to fit flush within the sidewall.

7 . The system of claim 6 , wherein the open-ended rigid conduit and sidewall are cylindrical.

8 . The system of claim 6 , wherein the flexible piezo-resistive sensor is affixed to the substrate such that the flexible piezo-resistive sensor deflects into a deflection cavity responsive to pressure applied to the user-interfacing portion.

9 . The system of claim 2 , further comprising:
a pressure transducing pad temporarily attachable to skin of a user between a radius of the user and a flexor carpi radialis tendon of the user and having a greater surface area than the user-interfacing portion of the deflection wall, the pressure transducing pad configured to deflect outwards from the skin proportionate to pressure applied by a radial artery such that outward deflection of the pressure transducing pad causes proportional deflection of the deflection wall towards the flexible piezo-resistive sensor when the user-interfacing portion is placed in contact with the pressure transducing pad.

10 . A system for detecting arterial pressure, comprising:
a flexible piezo-resistive sensor configured to alter an internal resistance responsive to pressure applied to a first side of the flexible piezo-resistive sensor; a fixed quantity of a pressure-transducing medium located in a sealed cavity on the first side of the flexible piezo-resistive sensor and configured to transmit pressure changes to the flexible piezo-resistive sensor; and a flexible cap surrounding the sealed cavity, the flexible cap configured to conform to tissue of a user so as to deflect into the sealed cavity responsive to blood flow through an underlying artery, thereby applying a pressure to the pressure-transducing medium proportionate to the arterial blood flow.

11 . The system of claim 10 , wherein the flexible cap comprises:
a sidewall sized to fit around the flexible piezo-resistive sensor, and a deflection wall capping the sidewall and shaped to conform between a radius and a flexor carpi radialis tendon, the deflection wall configured to deflect towards the flexible piezo-resistive sensor in proportion to pressure changes in a radial artery.

12 . The system of claim 11 , wherein the deflection wall includes a spring region between a user-interfacing portion of the deflection wall and the sidewall, the spring region biasing the deflection wall at a maximum distance from the flexible piezo-resistive sensor when no pressure is applied to the user-interfacing portion.

13 . The system of claim 12 , wherein the spring region is angled with respect to the flexible piezo-resistive sensor and decreases in diameter from the sidewall to the user-interfacing portion.

14 . The system of claim 12 , wherein the user-interfacing portion is perpendicular to the sidewall.

15 . The system of claim 11 , further comprising:
a substrate affixed to a second, opposite side of the flexible piezo-resistive sensor; and an open-ended rigid conduit affixed to the substrate surrounding the flexible piezo-resistive sensor, the open-ended rigid conduit configured to fit flush within the sidewall.

16 . The system of claim 15 , wherein the flexible piezo-resistive sensor is affixed to the substrate such that pressure applied to the flexible piezo-resistive sensor causes the flexible piezo-resistive sensor to deflect into a deflection cavity proportionate to the applied pressure, the deflection cavity located on the second side of the flexible piezo-resistive sensor.

17 . The system of claim 11 , further comprising:
a pressure transducing pad temporarily attachable to skin of a user between a radius of the user and a flexor carpi radialis tendon of the user and having a greater surface area than the user-interfacing portion of the deflection wall, the pressure transducing pad configured to deflect outwards from the skin proportionate to pressure applied by a radial artery such that outward deflection of the pressure transducing pad causes proportional pressure to be applied to the deflection wall when the user-interfacing portion is in contact with the pressure transducing pad.

18 . The system of claim 10 , further comprising:
a gel layer located on the first side of the flexible piezo-resistive sensor between the flexible piezo-resistive sensor and the pressure transducing medium.

19 . The system of claim 10 , wherein the flexible cap is a one-piece flexible cap.

20 . A wearable assembly for a radial artery tonometry sensor system, comprising:
an adjustable strap configured to secure the radial artery tonometry sensor system to a wrist of a user; a satellite housing connected to the adjustable strap; and a pressure transducing assembly located within the satellite housing, and comprising:
a flexible piezo-resistive sensor configured to alter an internal resistance as a function of deflection of the flexible piezo-resistive sensor;
a one-piece flexible cap configured to at least partially protrude through an opening in the satellite housing, and including:
a sidewall sized to fit around the flexible piezo-resistive sensor, and
a deflection wall capping the sidewall and shaped to conform between a radius and a flexor carpi radialis tendon, the deflection wall configured to deflect towards the flexible piezo-resistive sensor in proportion to pressure applied by a radial artery; and

a pressure-transducing medium sealed between the one-piece flexible cap and the flexible piezo-resistive sensor such that deflection of the deflection wall towards the flexible piezo-resistive sensor causes proportional deflection of the flexible piezo-resistive sensor.

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Saponas T Scott
• Basu Sumit
• Morris Daniel
• Gupta Sidhant
• Malladi Sailaja
• Tan Desney S
• Villar Nicolas
• Patel Shwetak N

Classifications

• A61B5/6824

  Arm or wrist · CPC title

• A61B2562/164

  the sensor is mounted in or on a conformable substrate or carrier · CPC title

• A61B5/681

  Wristwatch-type devices · CPC title

• A61B2562/0247

  Pressure sensors · CPC title

• A61B2562/168

  Fluid filled sensor housings · CPC title