Acoustic spirometer system
09763626 · 2017-09-19
Assignee
Inventors
- Lior Gonnen (Tel-Aviv, IL)
- David Groberman (Even Yehuda, IL)
- David Solomon (Zichron Ya'akov, IL)
- Rahav Cohen (Raanana, IL)
Cpc classification
A61B5/6898
HUMAN NECESSITIES
A61B5/0022
HUMAN NECESSITIES
International classification
Abstract
Embodiments of the present invention are directed a system using a microphone and a mobile computer device comprising a transducer through which a user is to exhale or inhale; the transducer is configured and operable to convert the spirometric flow rate into an audible signal having an audio frequency responsive to the spirometric flow rate, wherein the transducer comprises a rotor including a plurality of rotor blades configured to rotate the rotor responsive to a spirometric flow; wherein the microphone is external to the transducer and is adapted to detect the audible signal having the audio frequency and to convert the audible signal to a corresponding electrical signal having the audio frequency.
Claims
1. A system using a microphone and a mobile computer device connected to or integrated with the microphone, wherein the mobile computer device includes a processor, the system comprising: a transducer through which a user is to exhale or inhale; said transducer being configured and operable to convert a spirometric flow rate into an audible signal having an audio frequency responsive to the spirometric flow rate, wherein said transducer comprises a rotor comprising a rotor body including a plurality of rotor blades configured to rotate said rotor responsive to a spirometric flow; the rotor body defining a plurality of rotor chopping openings disposed between the plurality of rotor blades; and a ring-shaped part from which the plurality of rotor blades project; wherein the microphone is external to said transducer and is adapted to detect said audible signal having said audio frequency and to convert said audible signal to a corresponding electrical signal having the audio frequency; and a non-transitory computer readable medium including instructions executable by the processor, wherein said instructions, when executed, cause the processor to receive said corresponding electrical signal, to process the corresponding electrical signal, to derive said audio frequency and to output as a result the spirometric flow rate responsive to said audio frequency.
2. The system of claim 1, wherein said transducer comprises a stator including a stator plate with a plurality of stator openings, wherein said stator is rotatably connected to said rotor.
3. The system of claim 1, wherein said transducer is mechanically attachable externally to said microphone.
4. The system of claim 1, wherein said audio frequency is indicative of a peak expiratory flow rate and said result is thereby indicative of the peak expiratory flow rate.
5. The system of claim 1, wherein said audio frequency depends on a rotational speed of said rotor.
6. The system of claim 1, wherein said non-transitory computer readable medium is configured and operable to perform a signal processing for deriving said audio frequency, said signal processing comprising at least one of: a fast Fourier transform (FFT), an auto-correlation function, adaptive-additive algorithm, discrete Fourier transform, Bluestein's FFT processing, Bruun's FFT processing, Cooley-Tukey FFT processing, Prime-factor FFT processing, Rader's FFT processing, or a fast folding processing.
7. A transducer, comprising: a rotor comprising a rotor body including: a plurality of rotor blades configured to rotate said rotor in response to a spirometric flow, the rotor body defining a plurality of rotor chopping openings disposed between the plurality of rotor blades; and a ring-shaped part from which the plurality of rotor blades project; and a stator rotatably connected to said rotor, said stator comprising a stator body including an inner circle-shaped part comprising openings for chopping the air, and an outer ring-shaped part in which the air flows freely, wherein said transducer is configured and operable for converting a spirometric flow rate into an audible signal having an audio frequency responsive to the spirometric flow rate.
8. The transducer of claim 7, being mechanically attachable externally to a microphone.
9. The transducer of claim 7, wherein said audio frequency is indicative of a peak expiratory flow rate.
10. The transducer of claim 7, wherein said audio frequency depends on a rotational speed of said rotor.
11. The transducer of claim 7, wherein said audible signal has a characteristic audio frequency being produced by chopping spirometric flow between said stator body and said rotor body.
12. The transducer of claim 7, wherein said ring shaped part comprises an external ring-shaped part and an internal ring-shaped part defining the plurality of rotor chopping openings, the plurality of rotor blades extending radially between the internal and external ring-shaped parts.
13. The transducer of claim 7, wherein said rotor body comprises a first and second plurality of rotor openings having a different diameter.
14. The transducer of claim 7, further comprising a blade housing having openings between said blades.
15. The transducer of claim 7, wherein at least one of said plurality of stator and rotor chopping openings have an area up to 50% of the area of the ring-shaped part.
16. The transducer of claim 7, wherein the blades of the rotor are positioned at a certain angle in the range of 0° to 90° relative to a direction of the spirometric air flow.
17. The transducer of claim 7, further comprising a second array of blades having inclined and helix configuration to transform air flow from axial to rotational.
18. The transducer of claim 17, wherein said plurality of blades is positioned parallel to a rotation axis of the rotor.
19. The transducer of claim 7, wherein said rotor body comprises a rotor plate and said stator body comprises a stator plate.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Embodiments of the invention is herein described, in a non-limiting manner, by way of example only, with reference to the accompanying drawings, wherein:
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(12) The foregoing and/or other aspects will become apparent from the following detailed description when considered in conjunction with the accompanying drawing figures.
DETAILED DESCRIPTION OF EMBODIMENTS
(13) Reference will now be made in detail to features of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The features are described below to explain the present invention by referring to the figures.
(14) The features of the present invention may comprise a general-purpose or special-purpose computer system including various computer hardware components, which are discussed in greater detail below. Features within the scope of the present invention also include computer-readable media for carrying or having computer-executable instructions, computer-readable instructions, or data structures stored thereon. Such computer-readable media may be any available media, which is accessible by a general-purpose or special-purpose computer system. By way of example, without limitation, such computer-readable media can comprise physical storage media such as RAM, ROM, EPROM, flash disk, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other media which can be used to carry or store desired program code means in the form of computer-executable instructions, computer-readable instructions, or data structures and which may be accessed by a general-purpose or special-purpose computer system. Computer-readable media may include a computer program or computer application downloadable to the computer system over a network, such as a wide area network (WAN), e.g. Internet.
(15) In this description and in the following claims, a “computer system” is defined as one or more software modules, one or more hardware modules, or combinations thereof, which work together to perform operations on electronic data. For example, the definition of computer system includes the hardware components of a personal computer, as well as software modules, such as the operating system of the personal computer. The physical layout of the modules is not important. A computer system may include one or more computers coupled via a computer network. Likewise, a computer system may include a single physical device (such as a phone or Personal Digital Assistant “PDA”) where internal modules (such as a memory and processor) work together to perform operations on electronic data. While any computer system may be mobile, the term “mobile computer system” or the term “mobile computer device” as used herein especially includes laptop computers, netbook computers, cellular telephones, smart phones, wireless telephones, personal digital assistants, portable computers with touch sensitive screens and the like.
(16) The term “server” as used herein refers to a computer system including a processor, data storage and a network adapter generally configured to provide a service over the computer network. A computer system which receives a service provided by the server may be known as a “client” computer system.
(17) In this description and in the following claims, a “network” is defined as any architecture where two or more computer systems may exchange data. The term “network” may include wide area network, Internet local area network, Intranet, wireless networks such as Wi-Fi™, virtual private networks, mobile access network using access point name (APN) and Internet. Exchanged data may be in the form of electrical signals that are meaningful to the two or more computer systems. When data is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer system or computer device, the connection is properly viewed as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of computer-readable media. Computer-executable instructions comprise, for example, instructions and data which cause a general-purpose computer system or special-purpose computer system to perform a certain function or group of functions.
(18) The articles “a”, “an” as used herein, such as “a processor”, “a server”, “a sample” have the meaning of “one or more” that is “one or more processors”, “one or more servers” and “one or more samples”.
(19) Before explaining features of the invention in detail, it is to be understood that the invention is not limited in its application to the details of design and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other features or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
(20) Referring now to the drawings,
(21) Another example of acoustic transducer 20 may be in which air flow produces a shredded vortex in a frequency that is proportional to flow rate. The generated audible sound signal 24 from the shredded vortex may not be very strong when compared to other acoustic devices and may also have a broader spectrum of audio frequencies.
(22) Another example of acoustic transducer 20 may be based on an electronic acoustic device based on any kind of flow meter that has electronic output that modulates an acoustic frequency generator having a monotonous characteristic of flow rate (50-800 l/min) vs. frequency the range of 50 to 3000 Hz. Optionally the acoustic transducer 20 may produce a different frequency range for inspiration and expiration. The flow meter may include for instance an orifice plate placed in the path of airflow. An orifice plate is a device used for measuring the volumetric flow rate. It uses the same principle as a Venturi nozzle, namely Bernoulli's principle which states that there is a relationship between the pressure of the air and the velocity of the air. When the velocity increases, the pressure decreases and vice versa. From a sensed difference in air pressure before the orifice plate and after the orifice plate, the volumetric and mass flow rates may be obtained from Bernoulli's equation. For transducer 20, audible sound signal 24 generation may be performed by a microprocessor with an analog input of the sensed difference at the orifice which generates audible sound signal 24 corresponding to the sensed difference.
(23) A possible standard to follow and apply with respect to spirometer design may be British standard BS EN ISO 23747-2009. British standard BS EN ISO 23747-2009 entitled “Anaesthetic and respiratory equipment. Peak expiratory flow meters for the assessment of pulmonary function in spontaneously breathing humans” deals with Anaesthetic equipment, Flow meters, Anaesthesiology, Medical breathing apparatus, Electrical medical equipment, Medical equipment, Respiratory system, Flow measurement, Measuring instruments, Safety devices and Performance.
(24) Referring back to
(25) Processor 14 may include sample and hold circuitry and analog-to-digital converters (ADC) for converting audio electrical signal 26 to a corresponding digital signal. Storage 16 may store signal processing algorithms used by processor 14 for a signal processing of audio electrical signal 26. Results of the signal processing function of audio electrical signal 26 may be stored in storage 16 displayed or transferred to data communications 19.
(26) The use of transducer 20 which outputs an acoustic signal avoids the requirement of a cable between mobile device 1 and transducer 20. Moreover, the use of radio frequency RF transceivers or wireless interface such as Bluetooth™ may also be avoided, according to features of the present invention.
(27) Reference is now also made to
(28) Reference is now made to
(29) When spirometric air flow enters acoustic transducer 20, the air flows through the rotor blades which cause rotor 206 to rotate. Rotation of rotor 206 causes audible signal 24 to emanate from acoustic transducer 20 as spirometric air flows through mouthpiece aperture (not shown), through openings in stator plate 204, openings in rotor 206 and optionally openings in vent 208. Stator plate 204 may have a number of slots or openings which may be similar in size and shape to the slots or openings of rotor plate of rotor 206. As rotor 206 rotates, audible signal 24 is produced by the chopping and consequent pressure variation of spirometric flow between the stator plate 204 and the rotor plate of rotor 206. When the openings in both plates are at least partially aligned, air flows through the openings, and when the openings are not aligned, the air flow is blocked. The transformation between open and blocked openings creates the chopping action. The chopped air flow and pressure in the consequent variation create audible signal 24, the frequency of which may depend on the rotational speed of the rotor 206. Higher rotational speed causes higher sound frequency. Consequently, an audio electrical signal 26 with a characteristic audio frequency responsive to the spirometric flow rate is produced by the chopping. Cap 200 of
(30) Audible signal 24 may be received by microphone 12 of mobile computer device 1. Mobile computer device 1 may be held in the vicinity of transducer 20 by the hand of the user as shown in
(31) Reference is now made to
(32) Rotor plate 264 in
(33) Reference is now made to
(34) Rotor 206 and stator 202 may be configured so that the highest frequency of the sound signal at maximal spirometric flow is not noisy or disturbing to the user or to others. The lowest frequency should be high enough to be sensed by the microphone.
(35) For calculating the rotational speed of rotor 206, the air flow speed may be calculated in a first section (rotor blades section) which is proportional to a volumetric flow rate of the respiration. The volumetric flow rate is the percentage of the air which goes to the first section and the cross section area of the flow in the first section. The rotational speed may be proportional to the air flow speed in the rotor blades section and may depend on the angle and form of the rotor blades 290 of rotor 206.
(36) The spirometer may measure a wide range of flow between 50 liters/min to 800 liters/minute. This wide range may be divided to provide a system suitable for children and a system suitable for adults. The system suitable for children may have a lower flow range L1, and for adults a higher flow range L2.
(37) The resistance pressure of the peak flow/spirometer has to be lower than 1.5 cm of water per 1 liter per second (for example for flow of 10 liters per second, the resistance pressure should be less than 15 cm of water).
(38) The peak flow may measure transient peak flow during 0.1 second, and therefore the transducer preferably reaches a typical flow within 0.05 second.
(39) Since the measurement of the spirometric flow may be performed by handset with built in microphone, a transducer may produce frequency and intensity that can be detected by the handset and microphone that is not attached to transducer. The following parameters may be suggested:
(40) At low flow L1, the transducer's frequency may be more than 30 Hz, (100 Hz may be optimal), as the microphone may be less sensitive to lower frequencies, while the resistance pressure of the peak flow/spirometer may be over 0.2 cm of water in order to produce a detectable audible sound signal at low frequency.
(41) At high flow rates L2, transducer's basic frequency (first harmonic) may be less than 18 KHz, as the microphone may not be sensitive above 18 KHz. The system may be configured to provide a highest frequency of 3 KHz to decrease acceleration requirements for rotor and reliability concerns.
(42) Pressure drop can be estimated by a flow cross section A (not shown) i.e. the area of the openings through which the air flows and a flow rate using well known Bernoulli formula as a first approximation. Cross section A may be calculated from range L2 pressure limits or using 1.5 cm of water per 1 liter per minute.
(43) The basic frequency equals to rotor revolutions per second multiplied by the number of the openings in the rotor. The preferred number of openings may be 6 to 10. More openings may not be effective as a chopper. Fewer openings may require increasing the rotor speed and may require higher acceleration.
(44) Transducer basic frequency (first harmonic) rotor frequency may be calculated by the angle of rotor blades using known methods.
(45) The number of blades and profile of blades may be optimized to supply the required torque that is required to provide acceleration requirements of reaching the maximal flow at 0.05 seconds.
(46) In some embodiments, the rotor is constructed with minimal moment of inertia, using low density and high strength polymers, for example polycarbonate.
(47) Reference is made now to
(48) Reference is now made to
(49) Initialization of the system may include entering data such as age, sex, target respiration values, alert thresholds and medication schedules. Initialization may be performed by the user himself or by a practitioner located at a distant client or server as illustrated in
(50) In a measurement mode operation, the system according to one or more embodiments of the present invention may provide notification for a start of a measurement. During the measurement, the system according to one or more embodiments of the present invention may record the characteristic frequency of the acoustic transducer. The sound recording, sound analysis and frequency detection of the audible sound signal may be performed in real time on small time frames of, for example, 0.1 seconds in order to detect the sound signal. The signal analysis may be performed by a Fast Fourier Transform (FFT) to detect the maximum power at a particular frequency. The FFT may be performed in a defined frequency range e.g. 100-2000 Hz for an acoustic transducer held at a distance away from the mobile device by a user. Since environmental noises may interfere with the measurement, a noise rejection procedure may be suggested to avoid artifacts. The system according to one or more embodiments of the present invention may use noise rejection criteria having a characteristic transducer frequency (for example local maxima of the frequency in the range of 100-3000 Hz) 3 to 4 times the surrounding environmental root mean squared (RMS) audio noise. In case the particular (characteristic) frequency is not detected within 5-10 seconds, an error message may be presented and the user can start over the recording or close the application and the system according to one or more embodiments according to one or more embodiments according to one or more embodiments according to one or more embodiments according to one or more embodiments of the present invention goes into the stand-by mode.
(51) The flow rate calculation may be performed in real time by software installed in the mobile computer device (or on the cloud/server) or after the recording session. The recording session ends 5-10 seconds after the particular frequency detection or when the characteristic frequency is not detected. After the recording session is over, the flow rate may be calculated by using calibration data (from a function or a look-up table) of frequency versus flow rate. Additional respiratory parameters calculated from the flow rate curve as a function of time may be saved with a time stamp and optionally transferred to web-service management center, e.g. server illustrated in
(52) An analysis of the respiratory parameters may include comparing the respiratory parameters to predefined values, and in case of deviation from the normal values an alert may be presented to the user, with recommendations. The analysis may be performed in software of the mobile computer device or in a facility that is supervised by a clinician. Device software and web servers' software may work as one system, which may enable cost-effective supervision by the clinician and access of data by authorized users for disease management.
(53) A scheduling of measurement may be performed by fixed schedule or by an adaptive regime. Fixed scheduling may be performed by programming time intervals between scheduled measurements or a time to measure, as indicated to the user. Adaptive scheduling may be based on the trending information and scheduled intervals. While the measured respiratory values are in a normal range, a measurement may be performed at pre-scheduled intervals. When the measured spirometric measurement results are not normal, the measurement intervals may be decreased according to a predefined logic.
(54) The application installable on the mobile computer device may enable the entering of user selectable parameters and/or treatment parameters that can be correlated to the respiratory measurement results and displayed on the same chart, or uploaded to the practitioner, for example. User selectable parameters may include: lifestyle factors: diet, exercise, monthly rhythms, daily circadian rhythms, introduction of new medications and withdrawal of medications. A user selectable parameter that may be correlated over a time period of spirometric measurements of respiratory parameters for asthma, for example, may be movement, e.g. aerobic exercise, of a user using over the time period using a mobile computer device which includes a built-in acceleration sensor. The system according to one or more embodiments of the present invention can therefore be configured to present and display combined charts of breathing parameters with other measurable or manually entered parameters.
(55) Although selected features of the present invention have been shown and described, it is to be understood the present invention is not limited to the described features. Instead, it is to be appreciated that changes may be made to these features without departing from the principles and spirit of the invention, the scope of which is defined by the claims and the equivalents thereof.