Method and apparatus for intelligent flow sensors
Inventors
Coifman, Robert E. • Forbes, Charles E.
Assignees
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Publication Number
US-10806373-B2
Publication Date
2020-10-20
Expiration Date
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.
Core Innovation
The invention describes an intelligent elastic, sterilizable bidirectional airflow sensor that measures fluid flow by using a movable flap coupled to a chamber sized and dimensioned to allow fluid to pass therethrough. The fluid causes the flap to move and vibrate, so that the sensor produces a first sensor signal component representing displacement of the flap and a second sensor signal component representing vibration of the flap. The displacement is representative of a flow rate of the fluid, and the vibration is representative of a frequency characteristic associated with the fluid.
A plurality of piezoresistive sensors are disposed on opposite sides of the flap, with first and second circuit portions configured to sense different electrical changes in response to the flap’s mechanical behaviors. The first circuit portions sense a change in a first resistance in response to displacement and generate output signals containing a first sensor signal component representative of the displacement. The second circuit portions sense a change in a second resistance in response to vibration and generate output signals containing a second sensor signal component representative of the vibration.
The system includes a digital signal processor with a determining unit that transduces the displacement-based component and the vibration-based component into transduced sensor signal components, and amplifies them. The fluid flow rate determining unit generates a fluid flow rate signal representative of the flow rate from the transduced and amplified first sensor signal component, while the sound determining unit generates sound signals representative of the frequency characteristic from the transduced and amplified second sensor signal component. A computing device receives the flow rate signal and sound signals, determines the flow rate using the flow rate signal, and determines the frequency characteristic using the sound signals.
Claims Coverage
The partial content includes two independent claims. Each independent claim centers on an inventive architecture that uses a movable flap with piezoresistive sensors to generate separate displacement- and vibration-associated sensor signal components, followed by dedicated signal processing to determine a flow rate and a frequency characteristic.
Movable flap with symmetric piezoresistive sensors for displacement and vibration sensing
A housing with a chamber allowing fluid to pass, a flap coupled to the chamber to move when fluid passes, and a plurality of piezoresistive sensors disposed on first and second sides of the flap, the first and second sensors identical and symmetric with respect to at least one axis of symmetry; first circuit portions sense a change in a first resistance in response to displacement, and second circuit portions sense a change in a second resistance in response to vibration, producing a plurality of sensor output signals containing a first sensor signal component representative of displacement and a second sensor signal component representative of vibration.
DSP determining unit with voltage conversion, amplification, and separate flow and sound determination
A digital signal processor including a determining unit coupled to the first and second sensors and receiving the plurality of sensor output signals, the determining unit having a voltage conversion unit transducing the first and second sensor signal components into corresponding transduced sensor signal components, an amplification unit amplifying the transduced components, a fluid flow rate determining unit generating a fluid flow rate signal representative of the flow rate from the transduced and amplified first component, and a sound determining unit generating sound signals representative of the frequency characteristic from the transduced and amplified second component.
Computing device determining flow rate and frequency characteristic from flow-rate signal and sound signals
A computing device receiving the fluid flow rate signal and the sound signals, determining the flow rate of the fluid using the fluid flow rate signal, and determining the frequency characteristic using the sound signals.
Method inputting fluid to a movable flap and generating displacement and vibration sensor components
A method for determining both a flow rate and a frequency characteristic with a fluid flow sensing system having a housing and chamber, a moveable flap coupled to the chamber, and a plurality of piezoresistive sensors on first and second sides; sensing changes in first resistance in response to displacement representative of flow rate, and changes in second resistance in response to vibration representative of a frequency characteristic, including inputting the fluid so the moveable flap deflects and vibrates, and generating first sensor signal components with first circuit portions and second sensor signal components with second circuit portions from the sensor outputs.
Transducing and amplifying sensor components and generating flow-rate and sound signals
Receiving the plurality of sensor output signals including first and second sensor signal components at a determining unit with a processor and memory, voltage conversion unit, amplification unit, a fluid flow rate determining unit and a sound determining unit; transducing the plurality of first and second sensor signal components with the voltage conversion unit; amplifying the transduced first and second sensor signal components with the amplification unit; generating a fluid flow rate signal from the plurality of transduced and amplified first sensor signal components using the fluid flow rate determining unit; and generating sound signals from the plurality of transduced and amplified second sensor signal components using the sound determining unit, where the sound signals represent the frequency characteristic.
Determining flow rate and frequency characteristic with a computing device
Determining with a computing device the flow rate of the fluid using the fluid flow rate signal, and determining with the computing device the frequency characteristic of the fluid using the sound signals.
Across the independent claims, the core inventive elements are a movable flap with symmetric piezoresistive sensors using separate circuit portions to generate displacement-associated and vibration-associated sensor signal components, a determining unit that transduces and amplifies these components and separately produces a fluid flow rate signal and sound signals, and a computing device that determines flow rate from the flow-rate signal and determines a frequency characteristic from the sound signals, with corresponding steps in the method claim.
Stated Advantages
Simultaneously sensing and determining a flow rate and a frequency characteristic associated with the fluid.
Providing a sound determining unit that generates sound signals representing the frequency characteristic associated with the fluid.
Easier cleaning/disinfection and sterilizable use is discussed in the provided partial content summary.
Portability and modular non-medical uses are discussed in the provided partial content summary.
Documented Applications
Spirometry-style measurement using respiratory airflow, including determining flow rate and sound signals representative of a frequency characteristic associated with the respiratory air flow.
Forced Oscillation Technique (FOT) and Impulse Oscillometry (IOS) devices as implementations are described in the provided partial content summary.
Auscultation/breath sounds use is discussed in the provided partial content summary, including determining a frequency characteristic associated with respiratory air flow.
Non-medical airflow/wind and wind/sound uses are discussed in the provided partial content summary, including aircraft airflow/wind and sailboat wind/sound.
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