METHOD AND APPARATUS FOR INTELLIGENT FLOW SENSORS

• US 20120277615A1
• Filed: 12/03/2010
• Published: 11/01/2012
• Est. Priority Date: 09/23/2009
• Status: Active Grant

• Current Assignee: Respiratory Sciences, Inc.
• Original Assignee: Respiratory Sciences, Inc.
• Inventors: Coifman, Robert E., Forbes, Charles E.
• Granted Patent: US 10,806,373 B2
• Time in Patent Office: Days
• US Class Current: 600/538
• CPC Class Codes: A61B 5/0876 using means deflected by the fluid stream, e.g. flaps
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise
• CPC Class Codes: G01F 1/28 by drag-force, e.g. vane type or impact flowmeter

Abstract

A single sensor capable of detecting both airflow in spirometry and the full range of sound frequencies needed to track clinically relevant breath sounds is provided. The airflow sensor includes a movable flap with one or more integrated strain gauges for measuring displacement and vibration. The airflow sensor is inherently bidirectional. The sensor is an elastic flap airflow sensor that is capable of detecting data needed for both spirometry and auscultation measurements. The sensor is sterilizable and designed for the measurement of human respiratory airflow. The sterilizable sensor is also suitable for non-medical fluid flow metering applications. Additional devices such as sensors for the ambient level of various chemicals, sensors for temperature, sensors for humidity and microphones, may be affixed to the flap. When the strain gauge is placed in a conventional Wheatstone bridge configuration, the sensor can provide the airflow measurements needed for medical spirometry.

Claims

1. A fluid flow sensing system comprising:

a housing having a chamber that is sized and dimensioned to allow fluid to pass therethrough;

a flap provided within said chamber, wherein the fluid causes said flap to move when the fluid passes thereover;

a sensor coupled to said flap for generating an output signal when said flap moves, said sensor configured to sense a displacement of said movable flap and a vibration of said movable flap, said displacement of said movable flap being representative of a flow rate associated with the fluid and said vibration of said movable flap being representative of a frequency associated with the fluid; and

a determining unit receiving said output signal of said sensor and in response thereto, determining flow rate data associated with the fluid and determining frequency data associated with the fluid.

2. The system of claim 1 wherein the fluid is air, said flow rate is an air flow rate and said frequency is a sound.

3. The system of claim 1 wherein said sensor is a piezoresistive sensor.

4. The system of claim 3 wherein said piezoresistive sensor comprises first and second piezoresistive circuits and said first and second piezoresistive circuits being substantially perpendicular to each other.

5. The system of claim 4 wherein said first and second piezoresistive circuits have a resistance of about 120 ohms.

6. The system of claim 1 wherein said sensor is a strain gauge.

7. The system of claim 1 wherein said determining unit further comprises:

a voltage conversion unit for receiving said output signal of said sensor and converting said output signal into a voltage output signal; and

an amplification unit for receiving said voltage output signal and generating an amplified voltage output signal.

8. The system of claim 2 wherein said determining unit further comprises:

a voltage conversion unit for receiving said output signal of said sensor and converting said output signal into a voltage output signal;

an amplification unit for receiving said voltage output signal and generating an amplified voltage output signal;

an air flow rate determining unit for receiving said amplified voltage output signal and determining in response thereto said air flow rate data based at least in part upon said output signal of said sensor; and

a sound determining unit for receiving said amplified voltage output signal and generating in response thereto said sound data signal representative of said sound.

9. The system of claim 8 wherein said air flow rate determining unit further comprises:

a converter for converting said amplified voltage output signal into a digital output signal; and

a calculation unit for determining said air flow rate of the air based upon the digital output signal.

10. The system of claim 9 wherein said calculation unit includes a calibration curve that correlates the digital output signal to an air flow rate.

11. The system of claim 8 wherein said sound determining unit comprises:

a sound processing unit for generating said sound data signal in response to the amplified voltage output signal, and

a frequency conversion unit for receiving said sound data signal and in response thereto converting the signal into a frequency signal.

12. The system of claim 11 wherein the sound processing unit includes a sound card.

13. The system, of claim 11 wherein said frequency conversion unit includes a fast fourier transform module.

14. The system of claim 1 wherein said output signal of said sensor has a direct current electrical component that represents said flow rate associated with said fluid and a high frequency alternating current component that represents said frequency associated with said fluid.

15. A method for determining a flow rate and a frequency of a fluid using a sensor coupled to a flap, said sensor generating an output signal when said flap moves, said method comprising:

providing a flow of said fluid across said sensor;

sensing a displacement of said flap with said sensor, said displacement being representative of a flow rate associated with said fluid flow;

sensing a vibration of said flap with said sensor, said vibration being representative of a frequency associated with said fluid flow;

generating said output signal from said sensor; and

determining from said output signal said flow rate and frequency associated with said fluid flow from said sensed displacements and said sensed vibrations respectively.

16. The method of claim 15 wherein said steps of sensing both a displacement and a vibration of said flap occur simultaneously using said sensor.

17. The method of claim 15 wherein the fluid is air, said flow rate is an air flow rate, and said frequency is a sound, said determining step further comprising:

determining said air flow rate based at least in part upon said output signal of said sensor; and

generating said sound representative of the sound associated with the air based at least in part upon said output signal of said sensor.

18. The method of claim 17 wherein said step of determining further comprises:

converting said output signal into a voltage output signal;

generating an amplified voltage output signal from said voltage output signal;

determining said flow rate based on said amplified voltage output signal; and

determining said frequency based on said amplified voltage output signal.

19. The method of claim 18 wherein:

said step of determining said flow rate further comprises the steps of

converting said amplified voltage output signal into a digital output signal; and

determining said airflow rate based upon the digital output signal; and

said step of determining said frequency further comprises the steps of

generating a frequency data signal based on said amplified voltage signal; and

converting said frequency data signal into a frequency waveform.