Patent Application
20140155708
The present disclosure relates generally to determining physiological parameters of a patient. More particularly, the present disclosure relates to systems, methods and related apparatus for determining physiological parameters with sensors coupled to audio interfaces of electronic devices.
Conventional thermometers, blood pressure measurement devices, spirometers, perineometers, ECGs, EEGs, and other devices for measuring physiological parameters are typically standalone units. Standalone electronic devices for measuring physiological parameters usually contain a power source, a microcontroller, local storage, and a custom display mechanism along with the basic circuit needed to perform the sensing. This makes for relatively complex systems, costly to manufacture, and with many points of potential failure. They are therefore limited in their functionality, difficult to upgrade, and/or relatively expensive.
It is, therefore, desirable to provide improved systems and methods for determining physiological parameters.
Some aspects provide methods, systems and related apparatus for controlling an electronic device to operate an external sensor connectable to an audio interface of the electronic device by applying a first harmonic driving signal to a first contact and a second harmonic driving signal to a second contact of the audio interface for driving the external sensor, receiving a response signal at a third contact of the audio interface, adjusting at least one of the first and second harmonic driving signals, determining one or more physiological parameters based on characteristics of the first and second harmonic driving signals and the response signal, and outputting the determined one or more physiological parameters.
One aspect provides a system comprising a driving signal generator for applying a first harmonic driving signal to a first contact and a second harmonic driving signal to a second contact of the audio interface for driving the external sensor and adjusting at least one of the first and second harmonic driving signals, a response signal detector for receiving a response signal at a third contact of the audio interface, a physiological parameter extractor for determining one or more physiological parameters based on characteristics of the first and second harmonic driving signals and the response signal, and an output for outputting the determined one or more physiological parameters.
Another aspect provides a thermometer for connecting to an audio interface of an electronic device, the thermometer comprising a jack plug having first and second contacts for receiving first and second harmonic driving signals from the electronic device and a third contact for returning a response signal to the electronic device, and a temperature sensor consisting essentially of a thermistor connected between the first and third contacts and a reference resistor connected between the second and third contacts.
Another aspect provides an adaptor for connecting to an audio interface of an electronic device, the adaptor comprising a jack plug having first and second contacts for receiving first and second harmonic driving signals from the electronic device and a third contact for returning a response signal to the electronic device, and a pressure sensor having a pressure sensitive area, the pressure sensor connected as a bridge across the first and second contact to provide the response signal to the third contact, between the first and third contacts and a reference resistor connected between the second and third contacts.
Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.
Generally, the present disclosure provides methods and systems for controlling external sensors through audio interfaces of electronic devices. Example embodiments are described herein with reference to hand held electronic devices such as smartphones or the like, but it is to be understood that the systems and methods described herein may be implemented in any type of electronic device with an audio interface and suitable signal generating and processing capabilities, including without limitation smartphones, feature phones, personal digital assistants, tablet computers, netbook computers, laptop computers, portable gaming systems, portable music players equipped with processors, desktop computers, or the like.
Performing medical sensor measurements with portable devices such as mobile phones is advantageous for purposes of recording and transmitting readings, providing power to the sensor, data storage, powerful processors for advanced analytics, ease of upgrade and addition of application features, as well as facilitating a better user interface. Enhanced user interaction is possible through the versatile input and output mechanisms of a mobile phone, allowing for example to input supporting patient information, to guide the patient for ensuring optimal sensor placement, and to provide a richer feedback with the results, including treatment options, graphing of historic data trends and other relevant context.
By providing sensors connected directly to a mobile phone or other electronic device, embodiments disclosed herein eliminate the need for many components of typical standalone devices for measuring vital signs or other physiological parameters (such as separate power sources, microcontrollers, custom displays, etc.), as their functions are inherent to the mobile phone itself. These embodiments reduce the complexity of the sensor design and lower the cost of sensor manufacture. Due to the relative ease of software upgrades, the application controlling the sensor can be incrementally improved and updated. Embodiments described herein are configured to take advantage of the near universality of the audio interface in modern electronic devices. Certain embodiments also leverage the relatively high level of standardization of audio jacks and jack plugs. Furthermore, the consumer grade audio codecs in many electronic devices use sophisticated signal converters to achieve resolutions of 16 bits (15 ppm) or more. This by far outperforms the converters found in most custom microcontroller implementations that typically have resolutions of 10 bits (1000 ppm). This hardware level improvement of almost 100 times in signal quality can be leveraged to significantly improve the accuracy of the sensor readings. In addition, standard audio input and output signal levels and impedance ranges are directly compatible with a wide range of sensor types. In particular certain embodiments use sensors comprising bridge circuits of passive components for measurements, such as is the case for pressure and temperature sensing as discussed below.
There is however a significant difference between the audio interface and typical sensor interfaces in that the audio signal channel is designed to operate strictly on AC signals, whereas conventional sensor interfaces rely on DC signals for sensor actuation and detection. While it is possible to use an audio signal line to transmit DC sensor signals by means of amplitude and/or frequency modulation of AC carrier signals that are encoded and decoded at each end of the audio channel, this would require the presence of additional converter electronics between the sensor and the phone audio connector, which would be detrimental to the purpose of using a phone or other electronic device for eliminating custom electronics, as well as reintroduce the need for a separate sensor power source.
The standard microphone connection of an audio interface such as a mobile phone headset jack outputs a small voltage, which is used to drive the electret microphones commonly found in headsets. This “microphone bias” is sufficient to drive a single transistor or single ultra-low power device, but not to power a typical full sensor interface or signal conversion circuit.
Certain embodiments fully leverage the advantages and capabilities of modern electronic devices by employing sensor control methods and systems that are inherently AC in nature, such that the sensor input and output can be connected directly to the audio channel without additional signal conversion or conditioning, and without the need for a power source other than the microphone bias. This requires a new approach to sensor actuation, signal detection and processing.
Method 100 comprises applying harmonic driving signals to a pair of contacts of the audio interface at block 102. At block 104 a response signal received at another contact of the audio interface is measured. At block 105 method 100 determines whether the response signal is within a predetermined threshold of zero. If not, method 100 proceeds to adjust either one or both of the driving signals at block 106 to reduce the response signal. As one skilled in the art will appreciate, blocks 104-106 constitute a feedback loop for minimizing the response signal, may be executed substantially simultaneously, and may be implemented in a variety of ways.
When the response signal is minimized, method 100 proceeds to block 108, where one or more physiological parameters are determined based on characteristics of the driving signals applied to minimize the response signal. In some embodiments, physiological parameters may be determined based on a ratio of the amplitudes of the applied driving signals. In some embodiments, method 100 may also comprise detecting small variations of the response signal, and determining physiological parameters based on variations of the response signal at block 108. At block 109 the physiological parameter(s) are output to the patient and/or other user(s). For example, outputting physiological parameters may comprise displaying the physiological parameters on a display of the electronic device, generating audible signals with built-in speakers of the electronic device, generating a haptic signal, storing the physiological parameters in memory of the electronic device, sending the physiological parameters to one or more other devices using any suitable communication protocols available at the electronic device, passing the physiological parameters to another application through a programmatic interface, or any other form of output.
Method 100A comprises applying harmonic driving signals to a pair of contacts of the audio interface at block 102. At block 103, the amplitude of one of the driving signals is adjusted according to a predetermined amplitude profile (e.g., a linear ramp as in the example of
Response signal detector 204 provides feedback to driving signal generator 202 for adjusting the driving signals to minimize the response signal. Driving signal generator 202 provides a physiological parameter extractor 208 with characteristics of the driving signals (e.g. phase and amplitude) that minimize the response signal. In some embodiments physiological parameter extractor 208 receives a balance signal indicating a ratio of amplitudes of the driving signals. In some embodiments physiological parameter extractor 208 may also receive one or more signals generated based on the response signal received by response signal detector 204, as indicated by the dotted line connecting response signal detector 204 and physiological parameter extractor 208. Physiological parameter extractor 208 determines one or more physiological parameters based on characteristics of the driving signals, and optionally based on the response signal, as described further below, and provides the determined physiological parameter(s) for output at output 210.
Response signal detector 204A detects a local minimum in the amplitude of the response signal, and determines timing information thereof. The timing information of the local minimum in the response signal may be used by response signal detector 204A in conjunction with predetermined characteristics of the driving signals to determine the ratio of driving signals that caused the local minimum, and the ratio of driving signals may be provided to physiological parameter extractor 208A. Alternatively, the timing information may be provided directly to physiological parameter extractor in 208A. Physiological parameter extractor 208A determines one or more physiological parameters based on the signal from response signal detector 204A, as described further below, and provides the determined physiological parameter(s) for output at output 210. In other embodiments, other characteristics of the response signal including without limitation a maximum, an inflection point, or a specific non-zero value may be detected and provided to the physiological parameter extractor 208A.
A clinical thermometer is used to measure human body temperature. Body temperature reflects relative health, and a significantly elevated or lowered temperature can indicate illness. Conventional electronic clinical thermometers use a thermistor probe to measure temperature at a point that best approximates core body temperature, typically the mouth, armpit or rectum, and display the result with a resolution of typically 0.1 degrees. The accuracy of these devices is usually less, typically +/−0.2 degrees. Sufficiently accurate thermometers can be used to help predict female fertile periods by measuring basal body temperature (BBT). BBT is the lowest temperature reached while resting and is obtained in the morning after sleep. BBT typically peaks at least 0.4 degrees higher than normal over a 48-hour period when ovulation has occurred, and remains elevated until menstruation begins. A woman can use this method to predict ovulation by charting temperatures for several cycles to predict optimal likelihood of fertility. Accurate thermometers are also useful in a variety of other situations, as known in the art.
Certain embodiments provide low cost, robust and accurate thermometers which may be connected to audio interfaces of electronic devices. By eliminating all hardware for processing, storing, and displaying the measured temperature, and instead interfacing the thermistor directly to the audio port of a mobile phone or other portable electronic device, the complexity, cost and materials required for clinical grade thermometers can be significantly reduced.
With reference to an example embodiment comprising only two electrical components, they may be a thermistor having a variable resistance R and a reference resistor having a known resistance Rref. The reference resistor may be chosen to have a resistance close to that of the thermistor at a desired temperature. The desired temperature may vary depending on the intended use of the thermometer. For example, in some embodiments the desired temperature may be about room temperature, about body temperature, or anywhere in between. The ratio of driving amplitudes A(D1)/A(D2) is now equivalent to the balance of resistances b (b=R/Rref) and the temperature can be determined from:
where T is the temperature in Kelvin, R=bRref the thermistor resistance at the measured temperature, R0 is the resistance of the thermistor at a reference Kelvin temperature T0, and β is the thermal material constant of the thermistor. By nature of the null-detector arrangement the output and input gain of the mobile device does not enter the measurement.
Balancing of the driving signals in embodiments such as the example of
The bridge convergence factor is determined based on electrical noise and latency at the audio interface of the electronic device used to implement the control system. If for example the convergence factor is too large, the adjusted driving signal applied to one of the outputs of the audio interface may oscillate or diverge in an unstable manner.
In addition to ultra-low cost, an additional benefit of temperature sensors according to embodiments with control systems such as the example of
A dynamic temperature sensing control system such as system 300 of
The temperature should preferably be assessed from the measurement of the bridge balance point, as otherwise gain factors and non-linearities in the audio signal channels will affect the readings. Without using any feedback, a control system may perform a sweep to determine the minimum balance point. This can be done with a variety of waveform amplitude shapes, constructed such that the beginning of the sweep can be determined without knowledge of the phase relationship between the input and the output signals. In some embodiments, such control systems are operable to measure temperature with a precision on the order of 0.1 degrees. An example of such a control system is discussed below with reference to
A linear ramp is provided in the example amplitude profile shown in
The resulting response signal RES received at the microphone input is shown in
The frequency of the driving signals in the
The temperature of a probe with a temperature sensitive element takes some time to reach equilibrium with the temperature of an area of the body it is in contact with. In some embodiments, predictive algorithms may be used to predict the temperatures, as disclosed for example in U.S. Pat. No. 7,318,004.
A sphygmomanometer is a widely used device for the measurement of blood pressure, composed of an inflatable cuff to restrict blood flow, and a mercury or mechanical manometer to measure the pressure. Manual and semi-automatic devices are typically inflated with a bulb, while automated (digital) models typically use motorized inflation/deflation and read the pressure with an electronic sensor. Pressure measurements by sphygmomanometer may be used to determine a variety of physiological parameters relating to cardiovascular blood circulation including mean, systolic and diastolic blood pressure and heart rate. They may also be used to measure other physiological parameters such as respiration rate.
A spirometer is a widely used device used to measure various air flow characteristics of a patient's breathing. A typical spirometer functions as a flow meter that measures inspired and expired air volume over time. Spirometry may, for example, be used to measure a variety of respiratory parameters. Example measurements include:
A perineometer is a device for measuring voluntary contractions of the pelvic floor muscles. Perineometers may be used to measure the air pressure variations from an inflatable bladder, bulb or tube inserted into the vagina, or the mechanical strain variations from a strain gauge in a mechanically compressible member inserted into the vagina. Perineometric measurements may be used for such purposes as Kegel exercises or similar muscular function measurements. The sensor measurement data is then analyzed to determine the strength of the muscular contractions and other physiological parameters. In other embodiments, the strength of contractions of various other muscles may be measured by configuring air pressure or mechanical strain gauge sensors in a variety of devices that may be appropriately squeezed or compressed, including without limitation grips that measure forearm strength at the hand.
Example embodiments disclosed herein eliminate the need for conventional custom electronics of a digital sphygmomanometer, spirometer or perineometer by providing methods and systems for operating pressure sensors connectable to an electronic device such as a smartphone or media player by interfacing a pressure sensor directly through the audio interface of the device. Some embodiments use a commercially available pressure sensor comprising a piezoresistive bridge, which is operated in AC mode at standard audio signal levels, as described further below.
A response cancellation block 430 receives a response signal from sensor 410A and controls signal sources 420A and/or 420B to minimize the response signal. The response signal is also multiplied by one of the driving signals (D1 in the illustrated embodiment) and a phase shifted driving signal (generated by phase shift block 425) by multipliers 440A and 440B, respectively. The multiplied response signals are low pass filtered at filter blocks 450A and 450B, and then provided as a response input to a blood pressure extraction block 460. Blood pressure extraction block 460 is also provided with a balance input (e.g., the ratio of amplitudes of the driving signals) from response cancellation block 430.
At blood pressure extraction block 460, the balance input can be used to determine the absolute pressure at any given time. Lock-in amplification of the response signal may be used to provide a high resolution reading of the blood pressure modulation.
A system such as system 400 of
A system such as system 470 of
In an alternate embodiment, the perineometry sensor may comprise a strain gauge within a mechanically compressible member. The strain gauge sensor registers the degree of mechanical strain imposed by the muscular contractions. Strain gauges may be implemented in a variety of forms including mechanical, electrically resistive or capacitive, piezoresistive, fiber-optical, as well as other implementations of similar functionality. Strain gauge sensors may be implemented in an analogous manner as an air pressure sensor in a circuit similar to
In example embodiments the stereo audio output is used to apply an AC voltage across the bridge of a sensor and the bridge response signal is recorded by the microphone input. No additional components are needed in these circuits. Methods and systems disclosed herein make it possible to replace the manometer of a conventional sphygmomanometer, or the sensor circuitry of a spirometer, with a small and inexpensive adaptor that plugs directly into the audio interface of a mobile or other electronic device.
Adaptor 500 of
Adaptor 600 of
The example embodiments discussed above are directed thermometry, sphygmomanometry, spirometry, and perineometry applications, but it is to be understood that other embodiments may be directed to other applications. For example, other types of sensors, including without limitation ECG sensors and EEG sensors, may be connected to audio interfaces of electronic devices in other embodiments.
Although example embodiments have been described herein with the reference to the accompanying drawings, it is to be understood that the invention is not limited to those exact constructions and operations, and that various other changes and modifications may be made by one skilled in the art without departing from the scope or spirit of the invention.
Embodiments of the invention may be implemented using specifically designed hardware, configurable hardware, programmable data processors configured by the provision of software (which may optionally comprise ‘firmware’) capable of executing on the data processors, special purpose computers or data processors that are specifically programmed, configured, or constructed to perform one or more steps in a method as explained in detail herein and/or combinations of two or more of these. Examples of specifically designed hardware are: logic circuits, application-specific integrated circuits (“ASICs”), large scale integrated circuits (“LSIs”), very large scale integrated circuits (“VLSIs”) and the like. Examples of configurable hardware are: one or more programmable logic devices such as programmable array logic (“PALs”), programmable logic arrays (“PLAs”) and field programmable gate arrays (“FPGAs”). Examples of programmable data processors are: microprocessors, digital signal processors (“DSPs”), embedded processors, graphics processors, math co-processors, general purpose computers, server computers, cloud computers, mainframe computers, computer workstations, and the like. For example, one or more data processors in a control circuit for a device may implement methods as described herein by executing software instructions in a program memory accessible to the processors.
Processing may be centralized or distributed. Where processing is distributed, information including software and/or data may be kept centrally or distributed. Such information may be exchanged between different functional units by way of a communications network, such as a Local Area Network (LAN), Wide Area Network (WAN), or the Internet, wired or wireless data links, electromagnetic signals, or other data communication channel.
For example, while processes or blocks are presented in a given order, alternative examples may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified to provide alternative or sub-combinations. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times.
In addition, while elements are at times shown as being performed sequentially, they may instead be performed simultaneously or in different sequences. It is therefore intended that the following claims are interpreted to include all such variations as are within their intended scope.
In some embodiments, the invention may be implemented in software. For greater clarity, “software” includes any instructions executed on a processor, and may include (but is not limited to) firmware, resident software, microcode, and the like. Both processing hardware and software may be centralized or distributed (or a combination thereof), in whole or in part, as known to those skilled in the art. For example, software and other modules may be accessible via local memory, via a network, via a browser or other application in a distributed computing context, or via other means suitable for the purposes described above.
Software and other modules may reside on servers, workstations, personal computers, tablet computers, data encoders, data decoders, PDAs, mobile phones, media players, and other devices suitable for the purposes described herein. Those skilled in the relevant art will appreciate that aspects of the system can be practiced with any suitable communications, data processing, or computer system configurations, including: Internet appliances, hand-held devices (including personal digital assistants (PDAs)), wearable computers, all manner of cellular or mobile phones, multi-processor systems, microprocessor-based or programmable consumer electronics (e.g., video projectors, audio-visual receivers, displays, such as televisions, and the like), set-top boxes, network PCs, mini-computers, mainframe computers, and the like.
Where a component (e.g. a software module, processor, controller, assembly, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.
Embodiments of the disclosure can be represented as a computer program product stored in a machine-readable medium (also referred to as a computer-readable medium, a processor-readable medium, or a computer usable medium having a computer-readable program code embodied therein). The machine-readable medium can be any suitable tangible, non-transitory medium, including magnetic, optical, or electrical storage medium including a diskette, compact disk read only memory (CD-ROM), memory device (volatile or non-volatile), or similar storage mechanism. The machine-readable medium can contain various sets of instructions, code sequences, configuration information, or other data, which, when executed, cause a processor to perform steps in a method according to an embodiment of the disclosure. Those of ordinary skill in the art will appreciate that other instructions and operations necessary to implement the described implementations can also be stored on the machine-readable medium. The instructions stored on the machine-readable medium can be executed by a processor or other suitable processing device, and can interface with circuitry to perform the described tasks.
Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by: replacing features, elements and/or steps with equivalent features, elements and/or steps; mixing and matching of features, elements and/or steps from different embodiments; combining features, elements and/or steps from embodiments as described herein with features, elements and/or steps of other technology; and/or omitting features, elements and/or steps from described embodiments.
It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole. In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details are not required. In other instances, well-known electrical structures and circuits are shown in block diagram form in order not to obscure the understanding. For example, specific details are not provided as to whether the embodiments described herein are implemented as a software routine, hardware circuit, firmware, or a combination thereof.
The above-described embodiments are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art without departing from the scope, which is defined solely by the claims appended hereto.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CA2013/050367 | 5/13/2013 | WO | 00 | 1/24/2014 |
| Number | Date | Country | |
|---|---|---|---|
| 61646841 | May 2012 | US |
