PATENT DOCUMENT

Publication Number: US-11083383-B1
Application Number: US-201816128044-A
Country: US
Kind Code: B1

Title: Portable electrocardiogram device

Abstract:
Cardiac monitor devices are described. An exemplary cardiac monitor device can take the form of an armband that can be worn by a user. The cardiac monitor device can be paired with an electronic device so that the user can access information of his or her heart activity. In one embodiment, the cardiac monitor device can include a body that can be worn at a limb of the user. The body can carry different electronic components. The electronic components can include an electrode configured to come into contact with a location of the limb and configured to measure a first electrical potential at the location. The electronic components can also include an antenna configured to capacitively couple with the body of the user to generate a second electrical potential. The electronic components can further include an amplifier configured to amplify the potential difference.

Claims:
What is claimed is: 
     
       1. A wearable device for detecting electrical activities of a heart of a user, the wearable device comprising:
 a housing, the housing carrying:
 an electrode configured to come into contact with a user&#39;s skin at a first location on the user&#39;s body and configured to measure a reference electrical potential at the first location; 
 an antenna configured to be positioned across an air gap between the housing and a second location on the user&#39;s body that is different from the first location so that the antenna is capable of being capacitively coupled with the body to generate a second electrical potential; 
 an amplifier configured to determine a potential difference between the reference electrical potential and the second electrical potential, wherein the potential difference represents the electrical activities of the heart; and 
 an output configured to transmit signals carrying information of the potential difference to an external circuit. 
 
 
     
     
       2. The wearable device as recited in  claim 1 , wherein the external circuit is carried by a portable electronic device having a display assembly capable of displaying the information in a form of electrocardiograph. 
     
     
       3. The wearable device as recited in  claim 1 , wherein the electrode comprises a metal moat surrounding a surface of the electrode. 
     
     
       4. The wearable device as recited in  claim 3 , wherein the metal moat comprises an outer wall that is grounded and that surrounds an inner wall. 
     
     
       5. The wearable device as recited in  claim 1 , wherein the wearable device is wearable at an upper arm of the user. 
     
     
       6. The wearable device as recited in  claim 1 , wherein the wearable device is limited to a single electrode. 
     
     
       7. The wearable device as recited in  claim 1 , wherein the housing further carries a parasitic capacitance reduction unit configured to reduce an effect of a parasitic capacitance of the amplifier. 
     
     
       8. The wearable device as recited in  claim 7 , wherein the parasitic capacitance reduction unit comprises a second amplifier and a capacitor that forms a feedback loop with at a non-inverting input terminal of the amplifier. 
     
     
       9. The wearable device as recited in  claim 1 , wherein the wearable device is an armband and the electrode is positioned on an interior facing surface of the armband. 
     
     
       10. The wearable device as recited in  claim 1 , further comprising a filter circuit capable of filtering noise with frequencies that are below 0.5 Hz and that are above 45 Hz. 
     
     
       11. A method carried out by a portable electronic device that is capable of presenting electrocardiographic information of a heart of a user, the portable electronic device having a processor, a wireless transceiver, and a display assembly, the method comprising:
 issuing, by the processor, a command to control a cardiac monitor device separated from the portable electronic device, wherein the cardiac monitor device is capable of monitoring electrical activities of the heart through capacitive coupling between an antenna of the cardiac monitor device located at a first location on the user&#39;s body and across an air gap to a second location on the user&#39;s body that is different from the first location; 
 transmitting, by the transceiver, the command to the cardiac monitor device; 
 receiving, by the transceiver, signals from the cardiac monitor device; and 
 presenting, by the display assembly, the electrical activities of the heart as visual content in a form of an electrocardiograph based on the signals. 
 
     
     
       12. The method as recited in  claim 11 , wherein the portable electronic device is a wrist-worn electronic device. 
     
     
       13. The method as recited in  claim 11 , further comprising storing, in a memory of the portable electronic device, data based on the signals from the cardiac monitor device as historical data of the electrical activities of the heart. 
     
     
       14. The method as recited in  claim 11 , further comprising issuing, by the processor, a notification regarding the electrical activities of the heart based on the signals. 
     
     
       15. The method as recited in  claim 11 , further comprising performing, by the processor, an analysis of current electrical activities of the heart compared to historical data of the heart. 
     
     
       16. A system for monitoring electrical activities of a heart of a user, comprising:
 an electrode configured to come into contact with a user&#39;s skin at a first location on a limb of the user; 
 an antenna configured to be positioned across an air gap between the antenna and a second location on the user&#39;s body that is different from the first location so that the antenna is capacitively coupled with the body; 
 a processor configured to generate a signal representing a potential difference between the electrode and the antenna that indicates the electrical activities of the heart; and 
 a display assembly controlled by the processor and capable of presenting the signal as visual content. 
 
     
     
       17. The system as recited in  claim 16 , wherein the electrode and the antenna are carried by a cardiac monitor device and the processor and the display assembly are carried by a portable electronic device, the cardiac monitor device being wearable by the user. 
     
     
       18. The system as recited in  claim 17 , wherein the cardiac monitor device and the display assembly are capable of communicating with each other wirelessly. 
     
     
       19. The system as recited in  claim 16 , wherein the electrode, the antenna, the processor, and the display assembly are carried by a wrist-worn electronic device. 
     
     
       20. The system as recited in  claim 16 , further comprising:
 an analog-to-digital convertor capable of digitalizing the potential difference as digitalized data; and 
 a memory capable of storing the digitalized data.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application No. 62/562,980, entitled “PORTABLE ELECTROCARDIOGRAM DEVICE,” filed Sep. 25, 2017, which is incorporated herein by reference in its entirety for all purposes. 
    
    
     FIELD 
     Described embodiments can relate to portable electrocardiogram devices. More specifically, described embodiments can relate to portable electrocardiogram devices that are wearable and can include an antenna. 
     BACKGROUND 
     Cardiac electric fields result in cardiac potentials that can be sensed through the body surface of a user using electrodes. By monitoring the electric fields of a heart, the activities of the heart can be monitored. Conventionally, electrocardiogram information can be constructed by attaching two electrodes at the user&#39;s body to complete an electrical circuit. In more advanced medical devices, multiple electrodes are used to monitor the activities of the heart from different angles. Since multiple electrodes are attached to the user&#39;s body, the movement of the user is often severely limited. As a result, a continuous monitor of cardiac electric fields in a prolonged period is normally not feasible outside of the hospital setting. 
     SUMMARY 
     This paper describes various embodiments of cardiac monitor devices and systems. 
     According to one embodiment, a wearable device for detecting electrical activities of a heart of a user is described. The device can include a housing configured to be in contact with skin of the user when the wearable device is worn. The housing can carry an electrode configured to come into contact with a location of the skin and configured to measure a reference electrical potential at the location. The housing can also carry an antenna configured to be positioned across an air gap from a body of the user so that the antenna can be capacitively coupled with the body to generate a second electrical potential. The housing can further carry an amplifier configured to determine a potential difference between the reference electrical potential and the second electrical potential. The potential difference can represent the electrical activities of the heart. The housing can further include an output configured to transmit signals carrying information of the potential difference to an external circuit. 
     According to another embodiment, a portable electronic device that can present electrocardiographic information of a heart of a user is described. The portable electronic device can include a processor that can issue commands to control a cardiac monitor device that is separated from the portable electronic device. The cardiac monitor device can monitor electrical activities of the heart through capacitive coupling between an antenna of the cardiac monitor device and a body of the user. The portable electronic device can also include a wireless transceiver capable of transmitting the commands to the cardiac monitor device and receiving signals from the cardiac monitor device. The portable electronic device can further include a display assembly that can present the electrical activities of the heart as visual content in a form of electrocardiography based on the signals. 
     According to yet another embodiment, a system for monitoring electrical activities of a heart of a user is described. The system can include an electrode configured to come into contact with a location of skin of an upper arm of the user. The system can also include an antenna configured to be positioned across an air gap from a body of the user so that the antenna can be capacitively coupled with the body. The system can also include a processor that can generate a signal representing a potential difference between the electrode and the antenna. The potential difference can represent the electrical activities of the heart. The system can further include a display assembly controlled by the processor. The display assembly can present the signal as visual content. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  illustrates a cardiac monitor device wearable by a user, in accordance with some embodiments. 
         FIG. 2  illustrates a box diagram representing a cardiac monitor system, in accordance with some embodiments. 
         FIG. 3  illustrates a box diagram representing a detection circuitry of a cardiac monitor device, in accordance with some embodiments. 
         FIG. 4A  illustrates a capacitor circuit, in accordance with some embodiments. 
         FIG. 4B  illustrates a second capacitor circuit, in accordance with some embodiments. 
         FIG. 5  illustrates a detection circuit that can detect the electrical potential of a heart, in accordance with some embodiments. 
         FIG. 6  illustrates a capacitance neutralization circuit, in accordance with some embodiments. 
         FIG. 7  illustrates a filter circuit, in accordance with some embodiments. 
         FIG. 8  illustrates a plan view of an electrode, in accordance with some embodiments. 
         FIG. 9  illustrates a flowchart depicting a method for monitoring cardiac information of a person, in accordance with some embodiments. 
         FIG. 10  illustrates a flowchart depicting a method for monitoring the activity of heart of a person, in accordance with some embodiments. 
         FIG. 11  illustrates a block diagram of an electronic device, in accordance with some embodiments. 
     
    
    
     Those skilled in the art will appreciate and understand that, according to common practice, various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings can be expanded or reduced to more clearly illustrate the embodiments of the present invention described herein. 
     DETAILED DESCRIPTION 
     Representative applications of methods and apparatus according to the present application are described in this section. These examples are being provided solely to add context and aid in the understanding of the described embodiments. It will thus be apparent to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are possible, such that the following examples should not be taken as limiting. 
     In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting; other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. 
     Conventional electrocardiogram monitor devices require at least two electrodes to be in physical contact with a user to complete a circuit in order to monitor the electrical activities of the heart of the user. One electrode is often required to be attached near the heart of the user to detect the electric field of the heart. Such arrangement often requires the user to maintain a certain posture. Hence, it can be difficult to continuously conduct electrocardiogram monitoring in a prolonged period because the movement of the user can be severely limited. 
     Embodiments described herein can relate to cardiac monitor devices that can detect the electrical activities of a heart through a single electrode. An exemplary cardiac monitor device can include an electrode that is configured to be in contact with a limb of a user. The cardiac monitor device can also include an antenna that is capacitively coupled with the body of the user using air as the dielectric. The antenna can serve to replace a second electrode. The electrode can generate a first electrical potential that represents the electrical potential of the limb of the user. The antenna, when capacitively coupled with the body, can generate a second electrical potential that represents the electrical potential of the heart. By determining the potential difference between the electrode and the antenna, the electric field of the heart can be monitored remotely through the antenna. 
     Since the cardiac monitor device can detect the electric field of the heart with a single physical contact point, the antenna and the electrode can be carried by a single housing. For example, in one case, a small consumer electronic device can include a housing that carries both the antenna, the electrode and circuitry that connects the two components. The consumer electronic device can take the form of an armband that can be worn by the user. The armband can have the capability to wireless communicate with another electronic device such as a smartphone, a tablet, or a smart watch so that the cardiac information can be transmitted and displayed by the other electronic device. In another example, the cardiac monitor device can be a component that is part of a smart watch. Since a single device that is wearable by a user can be used to monitor the electric field of a heart, the electrical activities of the heart can be monitored continuously in a prolonged period, such as in days or even in months. 
     An exemplary cardiac monitor device can include detection circuitry that can include the antenna and the electrode. An instrumentation amplifier can be connected to the antenna and the electrode to compare the potential difference from the two components. Since air is the dielectric for the capacitive coupling between the antenna and the body of the user, the capacitance can be relatively weak. Hence, the inherent or parasitic capacitance of the detection circuitry can become comparatively significant. A capacitance neutralization circuit can be added to the detection circuitry to reduce or account for the parasitic capacitance. The capacitance neutralization circuit can include an amplifier connected to a feedback loop of the instrumentation amplifier and can reduce the parasitic capacitance by adjusting the gain of the amplifier. 
     The electrical signals carrying the potential difference that represents the electrical activities of the heart can also be filtered to remove or reduce the noises in the signals. The detection circuitry of a cardiac monitor device can include a low pass filter to remove any high frequency signals. The detection circuitry can include a high pass filter to remove any direct current. In one case, significant noises can be present in the frequency range of 45 Hz to 60 Hz. A notch filter can be used to specifically remove signals in that frequency range. After being filtered, the electrical signals can be amplified multiple times. In one case, the signals can undergo an amplifier with a gain of 100 or so. The amplified signals can be filtered again to further remove the noises in the signals. The signals can then be digitalized and be presented in an electronic device as electrocardiographic information. 
     These and other embodiments are discussed below with reference to  FIGS. 1-11 ; however, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  illustrates an exemplary cardiac monitor device  100 , in accordance with some embodiments. A cardiac monitor device can take different forms, including a wearable device that can be removably coupled to a user&#39;s appendage. In the particular case shown in  FIG. 1 , cardiac monitor device  100  can take the form of an armband that can be removably coupled to a user  102 . While cardiac monitor device  100  is shown as being worn at upper arm  104  of user  102 , cardiac monitor device  100  can also be worn at other locations of user  102 , including, but not limited to, the wrist, leg, neck, or body. Also, while cardiac monitor device  100  is shown as a band in  FIG. 1 , cardiac monitor device  100  can take any other suitable form. Cardiac monitor device  100  can sometimes simply be referred to as a device or a monitor device. 
     Cardiac monitor device  100  can include a housing  108  that can carry circuitry and electronic components that can detect the electrical activities of the heart  106  of user  102 . The circuitry can include at least an antenna  110  and an electrode  112 . In some cases, cardiac monitor device  100  is limited to a single electrode  112 . Electrode  112  can be configured to come into contact with a location of the skin of user  102  such as at upper arm  104  to measure a first electrical potential at the location. For example, if housing  108  takes the form of a band, electrode  112  can be an exposed piece of metal or a metallic terminal that can be located on the interior facing surface of the band so that electrode  112  is in direct physical contact with the skin of upper arm  104  when user  102  wears cardiac monitor device  100 . Antenna  110  can be configured to be positioned across an air gap  114  from the upper body  116  of the user  102 . Antenna  110  can be capacitively coupled with heart  106  using the air gap  114  (i.e. air) between antenna  110  and upper body  116  of user  102  as the dielectric. Based on the coupling, antenna  110  can generate a second electrical potential. As such, cardiac monitor device  100  can monitor the electrical activities of heart  106  based on the two electrical potentials detected. 
     In some embodiments, cardiac monitor device  100  can wirelessly communicate with a portable electronic device  118  using any suitable wireless protocol such as Bluetooth® or WiFi®. Cardiac monitor device  100  can transmit the measured signals carrying information of the potential difference to portable electronic device  118  for further analysis, storage, Internet transmission, and/or display on display assembly  120  of electronic device  118  as visual content. The display of the electrical activities of heart  106  on display assembly  120  can take the form of an electrocardiograph. While electronic device  118  is shown as a wearable electronic device such as a wrist-worn electronic device, electronic device  118  can also take the form of smart phones, tablets or computers. 
     In some cases, cardiac monitor device  100  can itself be a smart device that includes data processing capability, display assembly, and Internet capability. In those cases, cardiac monitor device  100  can process and display the measured data of the cardiac information, such as heart rates and electrocardiograms. Cardiac monitor device  100  can further share the measured data to electronic device  118 . In one particular case, cardiac monitor device  100  can itself be a wrist worn electronic device such as an electronic wrist watch. Instead of being worn at the upper arm, cardiac monitor device  100  can be worn at the wrist. Alternatively, cardiac monitor device  100  that takes the form of a wrist watch can have a flexible band that can be worn at either an upper arm or a wrist. The capacitance between heart  106  and antenna  110  can be inversely related to the distance between heart  106  and antenna  110 . Since heart  106  can have a weak electric field, antenna  110  should be positioned at a close distance from heart  106 . Preferably cardiac monitor device  100  can be positioned at the upper arm of user  102  because the upper arm is in proximity to heart  106 , regardless of the movement of user  102 . However, other locations, such as the wrist, is also possible for cardiac monitor device  100 . 
       FIG. 2  is a system schematic box diagram of a system for displaying real time cardiac information of a user, in accordance with some embodiments. The dash lined box represents user  102  including his/her heart  106  and limb  104 . Cardiac monitor device  100  can include a detection circuitry  124  that can include antenna  110  and electrode  112 . Electrode  112  that can directly measure a first electrical potential of user  102  at limb  104 . Antenna  110  can form a capacitor  126  with heart  106  through capacitive coupling. Through determining and amplifying the potential difference between the first electrical potential and the second electrical potential, detection circuitry  124  can generate signals or data representing the electrical activities of heart  106 . Cardiac monitor device  100  can optionally include an analog-to-digital convertor capable of digitalizing the potential difference before the signals are transmitted or stored in a memory as digitized data. Cardiac monitor device  100  can include an output that can transmit signals carrying information of the potential difference to an external circuit. The output can take various forms. In one case, the output can be a transceiver  128 . 
     The external circuit can be carried by a portable electronic device. For example, cardiac monitor device  100  can be paired with electronic device  118  so that signals or data representing the electrical activities of heart  106  can be transmitted from transceiver  128  to transceiver  130  of electronic device  118 . Electronic device  118  can include processor  132  that can analyze the signals and data. In some cases, processor  132  can also issue a command to control cardiac monitor device  100 . The command can be transmitted from transceiver  130  to transceiver  128  to control cardiac monitor device  100 . Processor  132  can also generate signals that can represent potential differences between electrode  112  and antenna  110 , which can represent the electrical activities of heart  106 . Electronic device  118  can include a memory  134  capable of storing data. Processor  132  can cause the data values of the signals saved in the memory  134  as historical data of the electrical activities of heart  106 . Processor  132  can also retrieve historical data of heart activities of user  102  from memory  134  to compare the historical data to the real time data. Electronic device  118  can also include a display assembly  136  that can present cardiac information based on the electrical activities of heart  106  analyzed by processor  132 . Controlled by processor  132 , display assembly  136  can present the electrical activities of heart  106  in a form of electrocardiograph. In other words, display assembly  136  can display signals sent from cardiac monitor device  100  as visual content. The visual presentation of cardiac information can take the form of heart rate, electrocardiography, and/or other suitable presentations. Processor  132  can provide analysis of a user&#39;s health condition based on the cardiac information and/or based on the current electrical activities of heart  106  compared to historical data of heart  106 . Processor can in turn cause display assembly  136  to issue a notification regarding the electrical activities of heart  106  based on the analysis. 
     In some embodiments, cardiac monitor device  100  can optionally include a processor  138  that can analyze the potential difference between antenna  110  and electrode  112 . Processor  138  can perform the activities that are the same as processor  132 . Cardiac monitor device  100  can also optionally include memory  140  that can store historical data of the electrical activities of heart  106 . 
       FIG. 3  illustrates a schematic box diagram of detection circuitry  124 , in accordance with some embodiments. While  FIG. 3  illustrates an exemplary component arrangement in the circuitry, it is understood that some of the components can be optional. Also, the order of some of the components can be changed. Detection circuitry  124  can include electrode  112  that can detect a first electrical potential of limb  104 . In one case, first electrical potential of limb  104  can serve as the reference potential of detection circuitry  124 , which can be treated as the ground of detection circuitry  124 . Detection circuitry can also include antenna  110  that is capacitively coupled with the heart  106  of user  102  to form capacitor  126  to generate a second potential. Since the capacitance generated can have a small value (e.g. in the magnitude of pico-Farad or even femto-Farad), the parasitic capacitance of the circuitry  124  can have a comparatively significant magnitude. Hence, a capacitance neutralization circuit  302  can be coupled to detection circuitry  124  to remove or minimize the effect of parasitic capacitance. Capacitance neutralization circuit  302  can sometimes be referred to as a parasitic capacitance reduction unit. 
     Detection circuitry  124  can include an instrumentation amplifier  306  that can compare the potential difference between the first potential and the second potential. Instrumentation amplifier  306  can be a type of differential amplifier circuit that can mainly serve to determine the potential difference between electrode  112  and antenna  110 . The difference can also optionally be amplified based on the gain of instrumentation amplifier  306 . However, in one case, the amplification can be performed in a more downstream component. In such case, instrumentation amplifier  306  can have a gain of 1. It should be understood that other value of the gain of instrumentation amplifier  106  is also possible. 
     After the potential difference is determined, the electrical signal can undergo a filter circuit  308  that can include one or more filters that filter different frequencies of electrical signals. Typical bio-potential of electrocardiogram signals can have a frequency range of 0.05 Hz to 150 Hz and signal amplitude range from 0.1 mV to 5 mV. The detection of the electrical activity of a heart can be subject to different sources and levels of noises. One potential significant source of noise is from electromyogram, which can have a frequency range of 25 Hz to 3060 Hz and signal amplitude that can be significantly stronger than the signals of electrocardiogram. Electromyogram can have a noticeable overlap in frequency with electrocardiogram in the range of 45 Hz to 60 Hz. Another potential significant source of noise is any alternating current and any coupling with alternating currents. A typical alternating current can have a frequency range of 50 Hz to 60 Hz and significantly stronger signals. Hence, in one embodiment, filter circuit  308  can allow signals with frequency range of 0.5 Hz to 40 Hz to pass. By using such frequency range, detection circuitry  124  can target a significant portion of typical frequency range of electrocardiogram signals that does not significantly overlap with electromyogram or alternating currents. 
     Filter circuit  308  can include a high pass filter that can eliminate low frequency electrical signals that are below the lower bound of the target frequency range of filter circuit  308 . The high pass filter can reduce or eliminate any unwanted direct currents in detection circuitry  124 . Filter circuit  308  can also include a low pass filter that can eliminate electrical signals with frequencies that are higher that the upper bound of the target frequency range of filter circuit  308 . The low pass filter can reduce or eliminate any unwanted alternating currents and other noises in detection circuitry  124 . Since the frequency range of 45 Hz to 60 Hz can present different sources of noises, filter circuit  308  can additionally include a notch filter that specifically removes frequency range of 45 Hz to 60 Hz. 
     After the electrical signals are filtered by filter circuit  308 , the electrical signals, which can solely or at least mainly represent the potential difference between antenna  110  and electrode  112 , can be amplified by amplifier  310 . Amplifier  310  can be any suitable amplifier such as an operational amplifier based multiplier. The multiplier can be inverting or non-inverting. Since the bio-potential detected can have a small value (in the range of 0.1-5 mV), the amplification can be in ten or hundred folds. In one particular embodiment, amplifier  310  can have a gain of 100. 
     After the amplification, the electrical signals at the output of amplifier  310  can be filtered again by a second filter circuit  312 . Since amplifier  310  can have a high gain, any residual noise may also be amplified along with the targeted potential difference. Hence, second filter circuit  312  can filter the amplified signals one more time to retain only the amplified signals at the target frequency range. Again, similar to first filter circuit  308 , second filter circuit  312  can include one or more high pass filter, law pass filter, and notch filter. 
     The amplified and filtered signals after amplifier  310  and the filters  308  and/or  312  can be transmitted to output  314 . Output  314  can be connected to a processor of cardiac monitor device  100  for analysis or to a transmitter of cardiac monitor device  100  to send out the signals to an electronic device for processing and storage. Output  314  can transmit signals carrying information of the potential difference to another component or another device. 
       FIG. 4A  illustrates a capacitor circuit  400  that illustrates the principle of one exemplary implementation of how antenna  110  and electrode  112  determine the electrical activity of heart  106 , in accordance with some embodiments. Capacitor circuit  400  can include a first capacitor  402  and a second capacitor  404  connected in series. First capacitor  402  can have two metal plates that are separated by air. Hence, first capacitor  402  can have a capacitance of C air , which can depend on the permittivity of air. A first metal plate  406  of first capacitor  402  can be connected to an electric field source  408  relative to a reference level  410 . A second metal plate  412  of first capacitor  402  can be connected to second capacitor  404 . Second capacitor  404  can have a capacitance C in . Second capacitor  404  is also connected to the same reference level  410 . For an alternating circuit, the impedance of a capacitance is equal to the inverse of jwC, wherein w is the frequency of the electrical current and C is the capacitance of the capacitor. Since first capacitor  402  and second capacitor  404  are connected in series, equation (1) below can represent the relationship between the electrical potential V s  of electric field source  408  and the electrical potential V in  at second capacitor  404 .
 
 V   in =[(1/ jwC   in )/(1/ jwC   in +1/ jwC   air )]× V   s   Eq. (1)
 
     By simplifying equation (1), the relation of V in  and V s  can be represented by equation (2) below. 
     
       
         
           
             
               
                 
                   
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     Now referring to  FIG. 4B , in accordance with some embodiment, a second capacitor circuit  414 , which can be equivalent to the general arrangement of capacitor circuit  400 , can be constructed using antenna  110  and electrode  112  to detect the electrical potential of heart  106 , which can be equivalent to the electric field source  408 . First capacitor  402  can be replaced by antenna  110  that is capacitively coupled with heart  106 . Second capacitor  404  can remain in second capacitor circuit  414  and can be connected to electrode  112 , which can serve as reference level  410 . In other words, since electrode  112  is configured to be in physical contact of limb  104 , the electrical potential of limb  104  is the equivalent of the reference level  410  in  FIG. 4A . It should be noted that while limb  104  in  FIG. 4B  is represented by a hand, electrode  112  can be in contact with other location of the body such as an upper arm. The electrical potential of heart  106  relative to electrical potential of limb  104  (i.e. the potential difference between heart  106  and limb  104 ) can be V s  in this system. V s  can be determined by V in  using the equation (2). In other words, the electrical activity of heart  106  can be determined by capacitor circuit  414  using antenna  110  that capacitively couples with heart  106  and electrode  112  that can be configured to be in contact with a part of the user&#39;s body. In one case, antenna  110 , capacitor  404 , and electrode  112  can be connected in series. 
       FIG. 5  illustrates a portion of detection circuitry  124 , in accordance with some embodiments. An exemplary instrumentation amplifier  306  can be added to point  502  of circuit  414  shown in  FIG. 4B  in accordance with some embodiments. In one case, capacitor  404  may not be a separate capacitor added to detection circuitry  124 . Instead, capacitor  404  may represent the inherent capacitance (or parasitic capacitance) of instrumentation amplifier  306 . Instrumentation amplifier  306  can have its non-inverting input terminal  506  connected to point  502 . It should be noted that point  502  can have the potential V in  relative to electrode  112 . Operational amplifier  306  can have its inverting input terminal  508  connected to its output  510  in a feedback loop. Hence, operational amplifier  306  can serve as a unity gain buffer that can measure the potential V in  at point  502  and that can output such potential. Operational amplifier  306  can output V in  for further processing so that the potential of heart  106  relative to electrode  112  can be determined based on Equation (2). In some cases, operational amplifier  306  can also include resistors (not shown) of different values at the feedback loop so that operational amplifier  306  can also serve as a multiplier to amplify V in . 
       FIG. 6  illustrates a portion of detection circuitry  124 , in accordance with some embodiments. An exemplary capacitance neutralization circuit  302  can optionally be added to detection circuitry  124  to reduce the parasitic capacitance of detection circuitry  124 . This particular embodiment of detection circuitry  124  can be constructed based on the circuit shown in  FIG. 5 . As explained above, capacitor  404  may represent the parasitic capacitance of instrumentation amplifier  306  or the parasitic capacitance of the system. Referring to equation (2), which is reproduced below, yin can have a value that is smaller than V s  because the denominator of equation (2) is equal or larger than the numerator. 
     
       
         
           
             
               
                 
                   
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                             a 
                             ⁢ 
                             i 
                             ⁢ 
                             r 
                           
                         
                         + 
                         
                           C 
                           
                             i 
                             ⁢ 
                             n 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
       
     
     It should be noted that V s  can have a relative small value because V s  can represent the biopotential of heart  106 . The parasitic capacitance of the system, Cm, can have a relatively large value compared to capacitance of air, Can, which can be in the magnitude of pico-Farad or even femto-Farad. If the parasitic capacitance of the system, Cm, is large, it can significantly reduce the value of yin according to Equation (2). 
     A capacitance neutralization circuit  302  can be added to reduce the effect of the parasitic capacitance of the system so that the detected value of yin can be maximized. A capacitor  602 , having a capacitance C n , can be added to the circuit and can reduce the effect of parasitic capacitance of detection circuitry  124 . The capacitor  602  can connect the non-inventing input terminal of instrumentation amplifier  306  and the output of instrumentation amplifier  306  at point  604  to form a feedback loop. An amplifier  606  with gain A can be connected to capacitor  602 . The overall capacitance of the system, C in ′, can be reduced based on Equation (3) below.
 
 C   in   ′=C   in +(1− A ) C   n   Eq. (3)
 
     By adjusting the gain of amplifier  606  and the value of the capacitance C n  of capacitor  602 , the overall capacitance of C in ′ of the system can be reduced. For example, in one case, the actual parasitic capacitance C in  can be estimated and capacitor  602  can have the capacitance value C n  equal to the estimated value of Cm. The gain of amplifier  606  can be set to 2. Hence, ideally the overall capacitance of C in ′ of the system can be zero or can at least be minimized. When the overall capacitance of C in ′ of the system is reduced, yin can be maximized according to Equation (4) below. 
     
       
         
           
             
               
                 
                   
                     V 
                     
                       i 
                       ⁢ 
                       n 
                     
                   
                   = 
                   
                     
                       V 
                       s 
                     
                     × 
                     
                       
                         C 
                         
                           a 
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                           i 
                           ⁢ 
                           r 
                         
                       
                       
                         
                           C 
                           
                             a 
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                             i 
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                             r 
                           
                         
                         + 
                         
                           C 
                           
                             i 
                             ⁢ 
                             n 
                           
                           
                             
                                 
                             
                             ′ 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     4 
                     ) 
                   
                 
               
             
           
         
       
     
     The capacitance neutralization circuit  302  can also include a comparator  608  that can compare the output of instrumentation amplifier  306  to a reference signal. Based on the comparison results, comparator  608  can control the gain of amplifier  606 . By dynamically adjusting the gain A of amplifier  606  to minimize the value of CZ, the effect of parasitic capacitance of the system can be minimized. 
       FIG. 7  illustrates a filter circuit  700 , in accordance with some embodiments. After instrumentation amplifier  306  outputs electrical signals that can represent V in  or amplified V in , the electrical currents can undergo one or more filters that can remove or attenuate components of the signals that are not in the targeted frequency range. Filter circuit  700  can be an exemplary filter circuit that can be used as the filter circuit  308  and/or  312 . It should be noted that the arrangement of filter circuit  700  is exemplary only and the exact configuration of filter circuits  308  and  312  can vary. Also, one or more components shown in filter circuit  700  can be optional. Filter circuit  700  can include a low pass filter  702 , a high pass filter  704 , and a notch filter  706 . The three filters can be arranged in any order. 
     Low pass filter  702  can include a capacitor  708  that can be connected to ground. Capacitor  708  can be connected to the main signal path in parallel. Capacitor  708  can have low impedance at high frequency so that signals with high frequency can be removed/attenuated. In one case, signals with frequency of 45 Hz or above can be removed/attenuated. 
     High pass filter  704  can include an inductor  710  that can be connected to ground. Inductor  710  can be connected to the main signal path in parallel. Inductor  710  can have low impedance at low frequency so that signals with low frequency can be removed/attenuated. In one case, signal with frequency of 0.5 Hz or below can be removed/attenuated. 
     Notch filter  706  can be used to remove signals at a certain specific frequency range. Notch filter  706  can include a capacitor  712  and an inductor  714  that can be connected in series. Capacitor  712  and inductor  714  combined can be connected to the main signal path in parallel. Capacitor  712  and inductor  714  combined can have low impedance at a specific frequency range based on the relative value of the capacitance of capacitor  712  and the inductance of inductor  714 . In some cases, since signals with frequency of 45 Hz to 60 Hz can include significant noises from different sources, notch filter  706  can specifically remove/attenuate components of the signals in such frequency range. 
       FIG. 8  is a plan view of an exemplary electrode  800 , in accordance with some embodiments. Electrode  800  can be used as the electrode  112 . Electrode  800  can include a surface  802  and a metal moat  804  that can surround surface  802  of electrode  800 . Metal moat  804  can be used as a shield to isolate noise from coupling to electrode  800 . Electrode  800  can be a metallic plate. Metal moat  804  can include an outer wall  806  that can generally surround an inner wall  808 . Inner wall  808  can be connected to the main detection circuitry while outer wall  806  can be connected to ground. In one case, both outer wall  806  and inner wall  808  can protrude from the surface  802 . Metal moat  804  can serve as a shield to remove the noise level of the cardiac monitor device in a manner similar to co-axial cable. Similar metal moat can also implemented for any antenna of a cardiac monitor device, such as antenna  110 . 
       FIG. 9  is a flowchart depicting a method  900  for monitoring cardiac information of a person, in accordance with some embodiments. The method  900  can be performed, at least in part, by one or more of the cardiac monitor device  100  or the portable electronic device  118 . At step  902 , the method can include measuring a first electrical potential at a location of the person. The location can be a location of a limb of the person. An electrode can be configured to be physically in contact with the person to measure the first electrical potential. At step  904 , the method can include coupling capacitively with the person using an antenna to generate a second electrical potential. The antenna can also be located at the limb of the person. At step  906 , the method can include determining a potential difference between the first electrical potential and the second electrical potential. The potential difference can represent the electrical activity of the heart of the person. At step  908 , the method can include filtering the electrical signals that carry the information of the potential difference. Signals with frequencies that are beyond the targeted frequency range (such as a certain range of typical ECG signals) can be filtered. At step  910 , the method can include amplifying the signals. The gain of the amplification can vary. In one case, the gain can be 100. At step  912 , the amplified signals can be filtered again to ensure a vast majority, if not all, of noise can be filtered and removed. The filtered signals can represent the electrocardiogram information of a user. At step  914 , the method can include presenting ECG information on a display. 
       FIG. 10  is a flowchart depicting a method  1000  for monitoring the activity of the heart of a person, in accordance with some embodiments. Since only a single electrode is needed to detect the cardiac information of a person using a cardiac monitor device that can take the form of a wearable device such as an armband, the activity of the heart can be monitored in a prolonged period continuously (such as continuously over days or even months). At step  1002 , the method can include monitoring, continuously, the cardiac information of a user, such as by detecting a potential difference between the heart and a limb of the user. The step can also include digitalizing the potential difference as digitalized data and storing the digitalized data in a memory. Step  1002  can include issuing and transmitting a command from a portable electronic device to a cardiac monitoring device. The digitized data can then be transmitted from the cardiac monitoring device to the portable electronic device as signals received by a transceiver of the portable electronic device. 
     At step  1004 , the method can include comparing the cardiac information monitored to historical data of the user. A processor of the portable electronic device can perform an analysis of the cardiac information via a comparison with the historical data of the user. At step  1006 , the method can include providing notifications and presenting visual content to the user based on the comparison and/or based on the cardiac information. This step can include presenting the potential difference as electrocardiographic visual content. The notifications can be presented on a display of the cardiac monitor device or a display assembly of a portable electronic device that can be paired with the cardiac monitor device. The notifications can also be routine notifications and/or notifications based on specific conditions. For example, a routine notification can be presented once a day to notify the user that his or her heart activity is normal. When an abnormal heart activity (such as an irregular heart beat, faster or slower than usual heart beat) is detected, notifications can be presented to provide warnings to the user. In addition, in response to the user&#39;s selection, cardiac information including electrocardiogram and heart beat can also be presented. 
       FIG. 11  is a block diagram of an electronic device  1100  that can represent the components of cardiac monitor device  100  and/or portable electronic device  118 , in accordance with some embodiments. It will be appreciated that the components, devices or elements illustrated in and described with respect to  FIG. 11  may not be necessary and thus some may be omitted in certain embodiments. The electronic device  1100  can include a processor  1102  that represents a microprocessor, a coprocessor, circuitry and/or a controller for controlling the overall operation of electronic device  1100 . Although illustrated as a single processor, it can be appreciated that the processor  1102  can include a plurality of processors. The plurality of processors can be in operative communication with each other and can be collectively configured to perform one or more functionalities of the electronic device  1100  as described herein. In some embodiments, the processor  1102  can be configured to execute instructions that can be stored at the electronic device  1100  and/or that can be otherwise accessible to the processor  1102 . As such, whether configured by hardware or by a combination of hardware and software, the processor  1102  can be capable of performing operations and actions in accordance with embodiments described herein. 
     The electronic device  1100  can also include user input device  1104  that allows a user of the electronic device  1100  to interact with the electronic device  1100 . For example, user input device  1104  can take a variety of forms, such as a button, keypad, dial, touch screen, audio input interface, visual/image capture input interface, input in the form of sensor data, etc. Still further, the electronic device  1100  can include a display  1108  (screen display) that can be controlled by processor  1102  to display information to a user. Controller  1110  can be used to interface with and control different equipment through equipment control bus  1112 . The electronic device  1100  can also include a network/bus interface  1114  that couples to data link  1116 . Data link  1116  can allow the electronic device  1100  to couple to a host computer or to accessory devices. The data link  1116  can be provided over a wired connection or a wireless connection. In the case of a wireless connection, network/bus interface  1114  can include a wireless transceiver. 
     The electronic device  1100  can also include a storage device  1118 , which can have a single disk or a plurality of disks (e.g., hard drives) and a storage management module that manages one or more partitions (also referred to herein as “logical volumes”) within the storage device  1118 . In some embodiments, the storage device  1118  can include flash memory, semiconductor (solid state) memory or the like. Still further, the electronic device  1100  can include Read-Only Memory (ROM)  1120  and Random Access Memory (RAM)  1122 . The ROM  1120  can store programs, code, instructions, utilities or processes to be executed in a non-volatile manner. 
     In some case, ROM  1120  can include a non-transitory computer readable storage medium configured to store instructions that, when executed by a processor included in electronic device  1100 , cause electronic device  1100  to perform different processes and methods described in accordance with different embodiments. The RAM  1122  can provide volatile data storage, and store instructions related to components of the storage management module that are configured to carry out the various techniques described herein. The electronic device  1100  can further include data bus  1124 . Data bus  1124  can facilitate data and signal transfer between at least processor  1102 , controller  1110 , network interface  1114 , storage device  1118 , ROM  1120 , and RAM  1122 . 
     As described above, one aspect of the present technology is the gathering and use of data available from various sources to improve the delivery to users of health content or any other content that may be of interest to them. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to provide insights into a user&#39;s general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals. Accordingly, use of such personal information data enables users to adjust their exercise routines or lifestyle. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide suggestions to a user for healthy recipes or the location of nearby fitness facilities. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of advertisement delivery services, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In another example, users can select not to provide health and fitness data for targeted advertisement delivery services, while providing other personal information data such as location. In yet another example, users can select to limit the length of time health and fitness data is maintained or entirely prohibit the development of a baseline health profile. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, content can be selected and delivered to users by inferring preferences based on non-personal information data or a bare minimum amount of personal information, such as the content being requested by the device associated with a user, other non-personal information available to the device, or publicly available information. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20180911
Publication Date: 20210810
Grant Date: 20210810
Priority Date: 20170925
Inventors: WU, CHIA CHI
TSUI, SHENG-YANG
LIN, SHU YU
Assignee: APPLE INC
CPC Classifications: [{"code": "A61B5/7225", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/7203", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/6831", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/6824", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/681", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/316", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/25", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/02438", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/0022", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/0006", "inventive": true, "first": true, "tree": "[]"}, {"code": "A61B5/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/7225", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/25", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/0022", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/02438", "inventive": true, "first": true, "tree": "[]"}, {"code": "A61B5/0006", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/7203", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/6824", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/681", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/6831", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/316", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/681", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/7203", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/6824", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/0022", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/25", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/316", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/02438", "inventive": true, "first": true, "tree": "[]"}, {"code": "A61B5/6831", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/7225", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/0006", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 77178990