Wearable Devices

Abstract

Various embodiments include apparatus and methods that use proximity sensors. One example of a device includes a transducer circuit including a sensor circuit with electrodes, an electrical signal sensing circuit, a substrate supporting and at least partially enclosing the transducer circuit and the electrical signal sensing circuit, and a communication circuit. The transducer circuit converts capacitance changes into electrical signals carried by the electrodes and responds to pressure and / or electric field modulation resulting from hemodynamic or pulse wave events. The electrical signal sensing circuit senses events in response to electrical signals from the transducer circuit. The substrate conforms to a portion of a user, bringing the sensor circuit in sufficient proximity to the user's skin to electrically sense hemodynamic or pulse wave events. The communication circuit responds to the electrical signal sensing circuit by transmitting data indicative of the hemodynamic monitoring.

Description

[Technical field]

[0001] Aspects of various embodiments relate to a proximity sensor circuit and associated sensing method for sensing hemodynamic changes (or pulse waves) in a user. [Background technology]

[0002] In the following description, various examples and applications are disclosed for understanding the present disclosure by way of non-limiting exemplary embodiments. Summary of the Invention [Problem to be solved by the invention]

[0003] In certain exemplary embodiments, aspects of the present disclosure include one or more sensor circuits constructed and arranged to sense hemodynamic changes (or pulse waves) in a user, the sensor circuit being configured to monitor physiological changes in a user using a single electrode placed at or near a measurement site. These and other aspects employ sensor circuits configured to sense hemodynamic changes consistent with one or more embodiments and / or features described below. [Means for solving the problem]

[0004] More specific exemplary embodiments relate to a device that includes at least one sensor circuit, the sensor circuit including an electrode and an electrical signal sensing circuit. The device can be used to non-invasively monitor one or more hemodynamic parameters in real time. For example, the electrical signal sensing circuit can be placed near or on the skin and can sense pulse wave events by monitoring changes in capacitance. The capacitance changes delivered by the electrodes are in response to pressure and / or electric field modulations resulting from pulse wave events or changes in pressure or blood flow (e.g., physiological) in the blood vessel. The electrodes can be used to determine capacitance changes between the electrodes and the skin of a user. The sensor circuit including the electrodes can be placed with a transducer circuit that is used to provide electrical signals indicative of the capacitance and / or pressure changes to the electrical signal sensing circuit. A pulse wave event changes the distance between the user's skin and the electrodes and / or changes the electric field distribution around the blood vessel, which in turn changes the relative capacitance measured by the sensor circuit. The change in capacitance over time can be processed using the electrical signal sensing circuit and can be used to generate and / or discriminate pulse waves. In various embodiments, the pulse waves are correlated to various hemodynamic parameters, for example, the pulse waves are processed to determine heart rate, blood pressure, arterial stiffness, and / or blood volume.

[0005] The electrodes may be in contact with and / or near the user's skin. In some embodiments, the electrodes (whether in contact or not) are restrained to the user by a mechanical restraint (e.g., a wristband, an elastic conforming band, or part of clothing) and / or an adhesive. The electrodes are located near blood vessels, preferably near palpable pulse points such as, but not limited to, the radial, brachial, carotid, tibial, and temporal pulse points.

[0006] In other specific aspects, the device includes multiple electrodes. For example, the device includes multiple sensor circuits, each sensor circuit including one of the multiple electrodes. The multiple electrodes are provided as part of a transducer circuit. The transducer circuit can be used to provide an electrical signal (e.g., digital) to the electrical signal sensing circuit indicative of capacitance changes in response to modulations of the distance, pressure and / or electric field between the user's skin and the electrode, modulations due to hemodynamic or pulse wave events. In various related aspects, the multiple sensor circuits are mechanically separated and / or arranged in an array (e.g., a sensor array). Each sensor circuit may be configured differently, e.g., to have different shapes, dielectric layers, positions, sensitivities, in other configurations described further below.

[0007] Various aspects relate to methods of using the above-described devices, including placing at least one electrode of the device near or on a user's skin and sensing a pulse wave event. The pulse wave event is sensed by monitoring capacitance changes in response to pressure and / or electric field modulation resulting from the hemodynamic or pulse wave event with electrical signal sensing circuitry of the device while the at least one electrode is located near or on the user's skin. The pulse wave event can be used to generate a pulse wave and / or determine various hemodynamic parameters. For example, the method can include using the pulse wave event to determine diastolic blood pressure, systolic blood pressure, arterial wall stiffness, and / or blood volume.

[0008] An illustrative method includes securing a transducer circuit including at least one sensor circuit with a flexible or bendable substrate of a wearable device. The substrate supports and at least partially encloses the transducer circuit and the electrical signal sensing circuit. The substrate further conforms to a portion of the user including a blood vessel and brings at least one electrode in sufficient proximity to the user's skin to electrically sense hemodynamic or pulse wave events via capacitance changes. The capacitance changes are in response to pressure and / or electric field modulation resulting from the hemodynamic or pulse wave events. The transducer circuit converts the capacitance changes into an electrical signal. The method further includes sensing the hemodynamic or pulse wave events in response to the electrical signal from the transducer circuit via the electrical signal sensing circuit, and using a communication circuit, within or outside the wearable device, to respond to the electrical signal sensing circuit by transmitting the hemodynamic monitor data to an external circuit.

[0009] Another aspect relates to the use of the device as part of a wearable device characterized by a flexible or bendable substrate configured and arranged to support and at least partially enclose the transducer circuitry and the electrical signal sensing circuitry and to conform to a portion of a user including a blood vessel for hemodynamic monitoring. As described above, the device includes a transducer circuitry including at least one sensor circuit having an electrode, an electrical signal sensing circuitry, and a communication circuitry.

[0010] The above description / summary is not intended to describe each embodiment or every implementation of the present disclosure. The following figures and detailed description exemplify various embodiments. [Brief description of the drawings]

[0011] Various exemplary embodiments will be better understood from the following detailed description when considered in conjunction with the accompanying drawings.

[0012] [Figure 1] 1 illustrates an example of an apparatus according to the present disclosure.

[0013] [Diagram 2] 1 illustrates an example of a device and the results of its interaction with a user's skin, in accordance with the present disclosure.

[0014] [Diagram 3] FIG. 2 is a block diagram illustrating one example of an implementation of electronics and / or signal flow from a device in accordance with the present disclosure.

[0015] [Figure 4] 1 illustrates various examples of devices according to the present disclosure. [Diagram 5] 1 illustrates various examples of devices according to the present disclosure.

[0016] [Figure 6] 1 shows an apparatus according to an embodiment of the present disclosure.

[0017] [Figure 7] 6(b) and (c) show example data obtained using the apparatus of FIG. 6(b) and (c), according to various embodiments.

[0018] [Figure 8] 1 shows an example of data acquired using an apparatus according to the present disclosure.

[0019] [Figure 9] 9A and 9B show an example of a multiple channel device according to the present disclosure and data acquired using the device.

[0020] [Figure 10] 1 shows an example of data acquired using an apparatus according to the present disclosure.

[0021] [Figure 11] 1 shows an example of data acquired using a device with planar contact electrodes in accordance with the present disclosure.

[0022] [Figure 12] 1 shows an example of data acquired using an apparatus according to the present disclosure.

[0023] [Figure 13] 1 shows an example of data acquired using an apparatus according to the present disclosure.

[0024] [Figure 14] 1 shows an example of data acquired using an apparatus according to the present disclosure.

[0025] [Figure 15] 1 illustrates an example apparatus and data acquired using the apparatus, according to the present disclosure.

[0026] [Figure 16] 1 shows an example of data collected using a device according to the present disclosure.

[0027] [Figure 17] 1 shows examples of data collected using a device and data collected using an arterial line, according to various embodiments.

[0028] [Figure 18] 1 illustrates examples of data collected using a device and collected using an arterial line, according to various embodiments.

[0029] [Figure 19] 1 shows examples of changes in heart rate and blood pressure collected using a device and collected using an arterial line, according to various embodiments.

[0030] [Figure 20] 1 shows examples of respiratory rates collected using a device, according to various embodiments.

[0031] [Figure 21] 1 shows example data collected using a multiple electrode device, according to various embodiments.

[0032] [Figure 22] 1 shows examples of data collected using a device with multiple electrodes located at different locations, according to various embodiments.

[0033] [Diagram 23] 1 shows example data collected using a multiple electrode device, according to various embodiments.

[0034] [Figure 24] 1 illustrates an example of a pulse wave generated using a wearable device, an arterial pathway, and an optical sensor, according to various embodiments.

[0035] Various embodiments described herein are susceptible to application and modification, and aspects thereof are shown by way of example in the drawings and described in detail. However, it is not intended to limit the present disclosure to the described embodiments. On the contrary, it is intended to include all applications, equivalents, and alternatives within the technical scope of the present disclosure, including the aspects defined in the claims. Also, the term "example" as used in this application is for illustration only, not for limitation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Aspects of the present disclosure are believed to be applicable to a variety of different types of devices and methods of using same that include a sensor circuit worn by a user and constructed and arranged to sense a pulse wave event aspect, condition, and / or characteristic of the user. In specific examples, aspects of the present disclosure have been shown to be beneficial when used as a strap located or wrapped around the wrist, although it will be apparent that the present disclosure is not necessarily limited to such. Various aspects will become apparent from the following description of non-limiting examples according to illustrative circumstances.

[0037] Thus, in the following description, various specific details are set forth to illustrate specific examples of the present disclosure. However, it will be apparent to one of ordinary skill in the art that one or more other examples and / or modifications thereof may be practiced without the specific details set forth below. For example, well-known features are not described in detail below to clarify the description of the examples herein. For convenience of description, the same reference numbers used in different drawings may represent the same components or additional instances of the same components. Also, although aspects and features are sometimes shown in separate drawings, features from one drawing or embodiment may be combined with features from other drawings or embodiments without the combination being explicitly shown or described.

[0038] Various embodiments of the present disclosure relate to a device that includes at least one sensor circuit having electrodes and an electrical signal sensing circuit. The device can be used to non-invasively and in real time monitor one or more hemodynamic parameters and pulse wave events. Surprisingly, it has been discovered that a common floating ground and a signal electrode that does not require contact with the user's skin can be used to measure the pulse wave events. In various embodiments, the pulse wave events can be monitored hands-free and without interference from environmental noise (e.g., human voice and other background noise, electrical interference, and ambient light). The electrodes (or electrode arrays) have relatively low power consumption (e.g., between 5 microwatts and 3 milliwatts, although embodiments are not limited thereto). In certain embodiments, power consumption can be further reduced by only storing data and / or transmitting the stored data in bursts after a trigger event (e.g., the occurrence of a particular cardiac event, such as a heart rate above a threshold, an event indicative of a problem, etc.). The electrical signal sensing circuitry can sense a pulse wave event by monitoring a pressure difference resulting from a pulse wave event or a capacitance change resulting from a pulse wave event while at least one electrode is positioned near or on the skin. The electrodes can be used to determine a capacitance change between the electrodes and the user's skin. A pulse wave event changes the distance between the user's skin and the electrodes, resulting in a relative change in capacitance and / or signal amplitude and quality measured by the transducer circuitry and the electrical signal sensing circuitry. The change in capacitance over time is processed by the electrical signal sensing circuitry and used to generate and / or determine a pulse wave. In various embodiments, the pulse wave is correlated with various hemodynamic parameters. Specific examples include pulse waves processed to determine heart rate, blood pressure, arterial wall stiffness, and / or blood volume. The electrodes are placed in contact with and / or near the user's skin. In some examples, the electrodes are placed close enough to the user's skin to electrically sense hemodynamic or pulse wave events via the capacitance change carried by the electrode (or electrodes).In this example, "sufficiently close" refers to a close distance, including to a blood vessel wall, from as far as 1 millimeter (mm) from the skin to as close as zero or in contact with the skin. In some embodiments, the sensor circuit (e.g., electrodes) are constrained on the user (whether in contact or not) using a mechanical restraint (e.g., a flexible or bendable substrate such as a wristband, sock, glove, sleeve, or other part of a wearable device or garment) and / or adhesive.

[0039] The capacitance changes delivered by the electrodes and respective sensor circuits are in response to pressure and / or electric field modulations resulting from hemodynamic or pulse wave events. More specifically, the sensor circuits and electrodes can acquire (or sense) capacitance changes through proximity sensing of the user's skin (which in existing capacitance sensor and other devices requires physical deformation), thereby functioning or being a proximity sensor. The proximity sensing and / or capacitance changes are in response to modulations in the distance between the user's skin and the sensor circuits and / or modulating fringe area lines.

[0040] In another specific embodiment, the device comprises a plurality of electrodes. The plurality of electrodes are disposed as part of a transducer circuit, which is used to provide a signal indicative of the change in capacitance and / or pressure to an electrical signal sensing circuit. For example, the transducer circuit comprises a plurality of sensor circuits, each of which comprises one of the plurality of electrodes. The electrical signal sensing circuit is disposed with the transducer circuit to monitor a pressure difference of less than 1 kPa, for example, between 0.3 kilopascals (kPa) and 1 kPa. The different electrodes can have different shapes, sensitivities, and / or placement locations. The transducer circuit can convert the capacitance change into an electrical signal (e.g., a digital signal). As disclosed herein, the transducer circuit and the electrical signal sensing circuit are supported and at least partially enclosed by a substrate.

[0041] As mentioned above, specific embodiments of the present disclosure relate to methods of using the device, the methods including placing at least one electrode of the device near or on the skin of a user and sensing a pulse wave event. The pulse wave event is sensed by monitoring a pressure differential due to the pulse wave event and / or monitoring a capacitance change (or a relative capacitance change) due to the pulse wave event using electrical signal sensing circuitry of the device while the at least one electrode is placed near or on the skin of the user. The pulse wave event can be used to generate a pulse wave and / or determine various physical and / or hemodynamic parameters. For example, the method includes using the pulse wave event to determine diastolic blood pressure, systolic blood pressure, arterial wall stiffness and / or blood volume.

[0042] Somewhat surprisingly, pulse wave events can be monitored using one or more electrodes placed on or near an arterial pulse point. For example, in response to a pulse wave event, each electrode provides a signal indicative of a pulse wave event. The electrode (or electrodes) are connected to a circuit, such as a transducer circuit. More specifically, each electrode (e.g., an electrical conductor) is connected to a respective sensor circuit used to measure or detect a signal indicative of a pulse wave event (e.g., capacitance value and / or capacitance change) from the electrode and provides the signal to the transducer circuit. The transducer circuit converts the signal indicative of the pulse wave event into an electrical signal and provides it to the electrical signal sensing circuit. The pulse wave event includes or indicates a hemodynamic response and / or a characteristic (e.g., contraction of the heart muscle) caused by and / or indicative of a heart beat (e.g., a heart beat or sound, a pulse of blood). The electrical signal sensing circuit (and / or transducer circuit) can include commercially available or custom designed circuitry for a capacitive touch screen and can communicate wirelessly or wired with a central processing unit (CPU). Additionally, the transducer circuitry and / or sensor circuitry may have a floating ground. The signal measured with the electrodes is due to small pressure differences and / or skin movements that modulate the fringe area at the electrodes, resulting in a measurable change in capacitance. The electrodes can be attached to the skin of a user (or other animal or living organism) using an adhesive (e.g., tape) or mechanically using a strap such as a watch band, bracelet, or wristband.

[0043] In a specific embodiment, the electrodes are surrounded by a dielectric layer (e.g., an encapsulant). When multiple electrodes are used, the dielectric layer of each of the multiple electrodes may have different structural characteristics to adjust the signal sensitivity of each electrode. Examples of such characteristics may include, among others, the thickness of the dielectric layer, the composition, structure, and resistance of the dielectric material used. Each of the multiple electrodes is associated with different characteristics based on at least one electrode shape and the dielectric layer used for the electrode. The different electrodes are used to output signals that are in response to the monitored pulse wave events. The signals from the different electrodes may be used in a differential mode to remove signals that may be common between the electrodes, such as temperature changes or user movements (e.g., noise), and to enhance signals or pulse wave events that may be measured by more sensitive electrodes, such as pulse wave pressure differences. In a related specific embodiment, one or more of the multiple electrodes are electrically shielded or insulated from each other. Also, a spacer may be used to adjust or set the distance between the at least one sensor circuit and / or electrode and the user's skin.

[0044] The signals provided by the electrodes may be used to determine various hemodynamic parameters. For example, in response to a pulse wave event, one or more signals indicative of a capacitance change are provided to an electrical signal sensing circuit. As described above, the capacitance change delivered by at least one electrode is a response to pressure and / or electric field modulation resulting from a hemodynamic or pulse wave event. The electrical signal sensing circuit uses the one or more signals to determine heart rate, diastolic blood pressure, systolic blood pressure, and / or arterial wall stiffness. The signals may be processed by one or more band pass filters or other signal processing techniques. For example, the signals may be filtered digitally or by a circuit design that minimizes artifacts due to factors such as pressure changes, movements such as breathing, arm movements, and external vibrations.

[0045] These surprising findings are particularly useful for non-invasive and / or continuous monitoring of blood pressure or other hemodynamic parameters. In particular embodiments, the devices may be used to provide sensitivity to pressure differences and / or capacitance changes caused by pulse wave events. Additionally, the devices and / or portions of the devices (e.g., electrodes) may be easier to fabricate compared to capacitive sensors due to fewer design parts and materials, allowing the subject devices to be more robust.

[0046] In a related specific embodiment, the device includes or is part of a portable / wearable device and / or apparatus capable of continuously monitoring heart rate and other hemodynamic effects such as diastolic blood pressure, systolic blood pressure, arterial wall stiffness. As an example, a smart bandage can be applied over the arterial pulse point and transmits data in real time to a receiver. Another example comprises a smart watch band with real time readout, data storage and / or transmission. Other embodiments involve small surface movements or pressure differences that modulate the fringe area at the electrodes.

[0047] Referring now to the drawings, Figures 1(a)-(b) show examples of devices according to the present disclosure. As shown in Figures 1(a)-(b), each device includes a sensor circuit with electrodes and an electrical signal sensing circuit. The devices can monitor pressure differentials and / or capacitance changes resulting from pulse wave events, which are used to determine one or more hemodynamic parameters. The pulse wave events can be used to generate a waveform or portion of a waveform indicative of a user's or animal's response to the pulse or a pulse (e.g., indicative of palpation of a heartbeat). The pulse wave events can be acquired as a signal and used to determine hemodynamic parameters such as heart rate, diastolic blood pressure, systolic blood pressure, and / or arterial wall stiffness.

[0048] FIG. 1(a) illustrates an example of a device including a sensor circuit 103 with an electrode 102 and an electrical signal sensing circuit 106. The electrode 102 is placed near or on the skin of a user (or other animal). The electrical signal sensing circuit 106 can include a proximity electrical signal sensing circuit that senses pulse wave events while the electrode 102 is placed near or on the skin of the user. In an embodiment, as further described below, the electrode 102 may be in direct contact with the skin or may be electrically or mechanically isolated from the skin, for example by air or a dielectric material. The electrode 102 is used to sense pressure and / or capacitance changes resulting from pulse wave events and output signals indicative of the sensed pressure or capacitance changes to the electrical signal sensing circuit 106 via the sensor circuit 103 and communication path 104 (e.g., the electrode is connected or plugged into the sensor circuit 103, which acquires and outputs signals indicative of capacitance values). The electrical signal sensing circuit 106 monitors the changes in pressure or capacitance (relative capacitance change) due to the pulse wave events and determines hemodynamic parameters such as heart rate from the monitored results. The changes in pressure and / or capacitance are measured based on the relative changes in capacitance that may be caused by changes in the distance between the electrodes 102 and the user's skin and / or changes in the electric field around the blood vessel.

[0049] In a specific embodiment, the sensor circuit 103 and / or electrode 102 (or electrodes) are mechanically constrained to the skin or other body part, such as by a wristband or a piece of clothing. The mechanical constraint may be by an elastic, flexible or bendable band and / or adhesive that attaches the sensor circuit 103 and / or electrode 102 to the skin or body. The adhesive may be applied to the outer periphery of the sensor circuit 103 (and not necessarily between the electrode 102 and the skin or other body part). In other embodiments, the electrode 102 does not physically contact the skin, for example, via a spacer or as described below. The capacitance change of the subject is relative, not absolute. The base capacitance of the electrode 102 depends on the respective shape and extent of the electrode 102 and / or sensor circuit 103 design. In an exemplary embodiment, the electrical signal sensing circuit 106 is capable of measuring an input range (e.g., capacitance change) of plus or minus 15 picofarads (pF) with up to a 100 pF offset. The base capacitance is on the order of 5-75 pF and the resulting pulse waveform signal (from a pulse wave event) has a maximum amplitude on the order of 0.1-1 pF, however, embodiments are not so limited and these values ​​may vary in different applications depending on the sensor and electrode design.

[0050] The relative change in capacitance over time can be used to generate and / or otherwise output a pulse waveform signal. The pulse waveform signal can be indicative of a hemodynamic parameter and / or can include an arterial pulse wave (also referred to as an "arterial pressure wave"). The change in capacitance due to a pulse wave event can be used to determine hemodynamic parameters, such as various hemodynamic parameters. As will be appreciated by those skilled in the art, an arterial pulse waveform is a waveform generated by the heart as it contracts and the wave travels along the arterial walls of the arterial tree. In general, there are two main components of this wave: a forward wave and a reflected wave. The forward wave is generated by the heart (ventricles) contracting during systole. This wave travels from the heart down the aorta and is reflected into the two iliac vessels at a bifurcation or "crossing" of the aorta. In a healthy individual, the reflected wave can return during diastole after the aortic valve closes. The returned wave has a notch and pushes blood through the coronary vessels, thus aiding in the perfusion of the heart. The speed at which the reflected wave returns is very important, because the stiffer the artery, the faster it returns. This then goes into systole, increasing the final blood pressure reading. The arterial pulse wave travels faster than the blood expelling it.

[0051] The exemplary device shown in FIG. 1(a) (and FIG. 1(b)) may have a variety of applications, as shown in FIG. 1(b). One exemplary application includes modifying the electrode 102 to electrically insulate it from the user's skin. The electrode 102 is insulated by adding a dielectric layer around and / or over (e.g., surrounding) a portion of the electrode 102. In one specific embodiment, the electrode 102 is connected to a circuit (e.g., a sensor circuit, such as a circuit board or chip) that is included in a wristband. The electrode 102 may be flexible. For example, the electrode 102 may be folded and hidden within the wristband when worn by the user. In alternative and / or additional embodiments, the electrode 102 may be integrated and / or embedded in the wristband. The dielectric layer may be formed from a variety of different dielectric (or insulating) materials, such as polyester (e.g., polyethylene terephthalate), polyolefin, fluoropolymer, polyimide, polyvinyl chloride, cellulose, paper, fabric, and / or other insulating materials. The dielectric layer may also have different thicknesses, for example on the order of 5-250 microns, and embodiments are not limited thereto, and the dielectric layer may be thicker or thinner depending on the strength and / or comfort of the user when wearing the device, or to adjust the sensitivity of the sensor circuit 103.

[0052] The pulse wave shape varies from user to user and / or based on the measurement location. For example, a wide pulse pressure suggests or indicates aortic regurgitation (during diastole, arterial pressure falls to allow blood to fill the left ventricle through the regurgitating aortic valve). A narrow pulse pressure indicates cardiac tamponade or other low output conditions (e.g., severe cardiogenic shock, massive pulmonary embolism, or tension pneumothorax). The pulse wave shape can also be adjusted depending on the location of the measurement, such as away from the aorta (e.g., brachial, radial, femoral, and dorsalis pedis). However, with the change in waveform shape, the mean arterial pressure (MAP) does not change and / or changes within a threshold range. This is because there is little change in resistance to flow from the aorta to the radial artery. The MAP begins to change when the location is moved to the arterioles. The change in shape from the aortic location to the dorsalis pedis includes an increase in the systolic peak, a dicrotic ridge further away from the systolic peak, a lower end diastolic pressure (e.g., wider pulse pressure) and a later arrival of the pulse (e.g., 60 second delay from the aorta to the radial artery). When the systolic peak is steeper and further down the arterial tree, the resulting shape is often referred to as terminal distal systolic pulse amplification.

[0053] Embodiments of the present disclosure are used to output pulse waves and determine various hemodynamic parameters using devices including wearable devices with non-invasive sensor circuits. The devices can be used to monitor heart rate, diastolic blood pressure, systolic blood pressure, arterial wall stiffness, blood volume, and other parameters. Previous invasive devices, such as arterial lines, are medically inserted into users, but are painful, restrict patient movement, and expose users to the risk of infection and other complications. For example, an arterial line is a thin catheter that is inserted into a user's artery. The catheter is often inserted into the radial artery in the wrist, but may also be inserted into the brachial artery in the elbow, the femoral artery in the groin, the dorsalis pedis artery in the foot, and / or the ulnar artery in the wrist. Arterial lines are used in intensive care and anesthesia to monitor blood pressure directly and in real time. Because insertion is painful, anesthesia (e.g., lidocaine) is used to make insertion more tolerable and help prevent vasospasm. Complications from arterial lines can cause tissue damage and even amputation. The device of the present disclosure can be used to non-invasively monitor blood pressure in real time. The device can avoid and / or mitigate risks associated with invasive devices, such as temporary occlusion of the aorta, pseudoaneurysm, hematoma formation or bleeding at the needle insertion site, abscess, cellulitis, median nerve paralysis, suppurative thromboarteritis, air embolism, compartment syndrome, and carpal tunnel syndrome, nerve damage, etc.

[0054] As shown in FIG. 1(b), various characteristics may be altered to adjust the sensitivity of the device and / or improve the signals obtained by the electrodes. FIG. 1(b) shows an example of a device with multiple electrodes 102-1, 102-2, and 102-3. Each electrode 102-1, 102-2, and 102-3 is used to sense pressure or capacitance changes due to pulse wave events (e.g., caused by changes in distance between an electrode and the skin surface) as described above. The electrodes 102-1, 102-2, and 102-3 are part of or form a transducer circuit 110 that provides one or more signals to an electrical signal sensing circuit 106. The electrodes 102-1, 102-2, and 102-3 may be placed at different locations on the device to improve location accuracy and / or provide one or more reference signals for different analyses. In one embodiment, each electrode 102-1, 102-2, and 102-3 provides a signal indicative of a pressure or capacitance change (due to a pulse wave event) to the electrical signal sensing circuit 106. In a specific embodiment, the transducer circuit 110 can have a floating ground. In another specific embodiment, at least one sensor circuit has a floating ground (e.g., two sensor circuits each have a floating ground, all sensor circuits each have a floating ground). Also, the transducer circuit 110 and at least one sensor circuit can both have a floating ground.

[0055] Although Figure 1(b) (as well as other illustrations, including but not limited to Figures 2(a), (b) and (d)) does not show sensor circuitry connected to the electrodes and / or to each of the electrodes, it will be apparent to one of ordinary skill in the art that in various embodiments, each electrode is connected to a sensor circuit as described above. Thus, while Figure 1(b) as well as other illustrations omit sensor circuitry for clarity, this is not intended to be limiting.

[0056] In various embodiments, the device (e.g., the electrical signal sensing circuit 106) may further comprise wireless communication circuitry. The wireless communication circuitry wirelessly communicates data from the electrical signal sensing circuit 106 to circuitry external to the device. The communication circuitry is constructed and arranged to communicate the acquired changes due to the hemodynamic pulse wave events to external processing circuitry. The communication circuitry may be located internal or external to the wearable device and / or device and responsive to the electrical signal sensing circuitry by transmitting hemodynamic monitoring data to the external circuitry. The device may also comprise power supply circuitry 112, as further described below.

[0057] In some embodiments, one or more of the plurality of electrodes 102-1, 102-2, and 102-3 may be electrically isolated from the user's skin. As described above, the electrodes 102-1, 102-2, and 102-3 may be isolated by adding dielectric layers 108-1, 108-2, and 108-3 to some or all of the plurality of electrodes 102-1, 102-2, and 102-3. The dielectric layers 108-1, 108-2, and 108-3 surround each of the electrodes 102-1, 102-2, and 102-3 and / or each of the sensor circuits. However, embodiments of the present disclosure are not limited to this case and may include a dielectric layer disposed over a portion and / or region of the electrodes that are positioned to contact the user's skin and / or at least partially surround each of the electrodes or sensor circuits.

[0058] As shown in FIG. 1(b), the transducer circuit 110 can be used to provide a differential mode to remove artifacts that shift the reference due to user movement, e.g., limb movement, breathing, and / or body temperature changes. In various embodiments, the different electrodes 102-1, 102-2, and 102-3 of the transducer circuit 110 have different constructional properties and / or characteristics that can be used to modulate the sensitivity of each sensor circuit comprising the electrodes. For example, the electrodes 102-1, 102-2, and 102-3 can have different shapes (e.g., geometries), be positioned at different locations relative to the user and / or device, and be made from different materials. In other embodiments, the different constructional properties and / or characteristics include different compositions, components, textures, and / or thicknesses of encapsulants that electrically isolate the electrodes. For example, the dielectric layers of each electrode 102-1, 102-2, and 102-3 can be formed from dielectric materials of different compositions, configurations, and / or thicknesses to vary the sensitivity and / or properties of the shielding used to separate the electrodes. Accordingly, the multiple electrodes may include an encapsulant constructed and arranged to set the sensitivity of each of the multiple electrodes.

[0059] In various embodiments, the device further comprises a power supply circuit 112. The power supply circuit 112 provides power to at least the electrical signal sensing circuit 106. In a particular embodiment, the power supply circuit 112 is a passive or inductive power supply circuit, for example, an inductive circuit. Examples of power supply circuits include batteries, solar power converters, electromechanical systems, wall plug-ins (e.g., mains electricity), and other power sources.

[0060] FIG. 2(a) shows an example of a device with a sensor circuit with an electrode 214 that interacts with the skin 218. As mentioned above, the sensor circuit and electrode convey a capacitance change upon proximity sensing of the user's skin (as opposed to being physically deformed as a capacitance sensor), thereby functioning as or being a proximity sensor. A (proximity) sensor circuit with a single electrode 214 placed near an arterial pulse point (e.g., artery 216) can be used to measure the arterial pulse wave via the capacitance change. Heart rate and other hemodynamic parameters can be derived from this waveform. The electrode 214 is in direct contact with the skin 218 or is electrically insulated or separated from the skin 218. It does not need to be mechanically coupled to the skin 218. The composition, configuration, and thickness of the electrical insulation are selected to adjust the sensitivity of the sensor. A spacer structure can be used to control the distance between the electrode and the skin. The circuit has a floating ground (e.g., the sensor circuit and / or the transducer circuit can have one floating ground).

[0061] An array of electrodes can be used to improve positional accuracy and / or provide a reference signal for different analyses. Signals can also be improved by electrode design that optimizes fringe area distribution. For example, in one embodiment, analog responses are sensed by an array of sensor circuits, each sensor circuit having a single electrode. Two or more electrodes in the array have different sensitivities, and the analog responses sensed by two or more sensor circuits in the array can be applied to different sensing applications.

[0062] Figure 2(b) shows an example of a pulse wave 209 sensed using the device of Figure 2(a). As shown, the periodicity of the pulse wave 209 reflects the cardiac cycle and can be used to determine the user's heart rate.

[0063] FIG. 2(c) shows an example of a mechanism for a device monitoring pulse wave events. As shown in FIG. 2(c), the user's skin 218 acts as a ground plane for the mechanism. Without being limited to a particular theory, the mechanism in accordance with one or more embodiments of the present disclosure is as follows: (i) the skin 218 acts as a ground plane, and arterial pressure changes cause a displacement of the surface of the skin 218, which changes the distance between the electrode 214 and the skin 218, which is measured as a change in capacitance; (ii) the potential of the blood (and the skin above it) in the artery 216 changes with the heartbeat, which changes the fringe area lines, which are reflected as a change in impedance; and (iii) a combination (contribution) of each of the above mechanisms is included.

[0064] FIG. 2(d) illustrates an example of the device shown in FIG. 2(c), further comprising one or more spacers that set a distance (e.g., a minimum distance) between at least a portion of the sensor circuit (e.g., electrode 214) and the skin 218. The spacers 217 have structures formed from a material and a length (e.g., distance from the electrode to the skin surface) that sets the distance between at least a portion of the sensor circuit / electrode and the skin. The length ranges from 0.1 millimeters (mm) to 1.0 mm, although embodiments are not so limited. The embodiment shown in FIG. 2(d) illustrates a square-shaped spacer, but embodiments are not so limited and may include two or more spacers and spacers of different shapes, for example, layers formed from material with non-flat and / or structural shapes.

[0065] 3 is a block diagram illustrating an example of an approach for implementing electronics and / or signal flow from a device (e.g., including sensor circuitry 324, transducer circuitry 326, electrical signal sensing circuitry 327, and communication circuitry 330) located near the skin of a user to a remote / wireless communication capable transceiver and CPU 334 (e.g., receiving via antenna 336) according to the present disclosure. CPU 334 and / or electrical signal sensing circuitry 327 are programmed to perform operations such as, but not limited to, process raw data indicative of the presence of specific hemodynamic signals, develop waveforms from the raw data, and / or evaluate the integrity, quality, and relevance of the hemodynamic signals and / or waveforms for a particular application related to the hemodynamic status or health of a user (e.g., indicative of a change in the user's heart rate or other hemodynamic indicators or parameters, such as diastolic blood pressure, systolic blood pressure, arterial stiffness, blood volume, and / or one or more indicators or parameters).

[0066] The electrodes of the sensor circuit 324 acquire capacitance changes in response to the pulse wave events and provide the capacitance changes to the transducer circuit 326. In one embodiment, the transducer circuit 324 is or includes a capacitance-to-digital converter. The capacitance-to-digital converter converts the capacitance values ​​(e.g., relative changes) to digital signals and outputs the digital signals to an electrical signal sensing circuit 327, which may include or be a microcontroller or other processing circuit. The electrical signal sensing circuit 327, using power from a power source 328, measures and / or records the arterial pulse waves, optionally conditions the signal, evaluates the quality of the data, and / or determines one or more hemodynamic parameters. The electrical signal sensing circuit 327 outputs the waveform and any other data to a CPU 334 via a communication circuit 330 (e.g., an integral transceiver) and an antenna 332.

[0067] The sensing device, as described herein, can be used to monitor pulse wave events in a hands-free manner and without interference from environmental noise (e.g., human voice and other background noise, electrical interference, and / or ambient light). Additionally, the electrical signal sensing circuitry can sense hemodynamic or pulse wave events in response to electrical signals from the transducer circuitry. The electrodes (or arrays of electrodes) have relatively low power consumption (e.g., between 5 microwatts (or less) and 3 milliwatts). In a specific embodiment, power consumption can be further reduced by storing data after a trigger event and / or only transmitting the stored data in a burst transmission. The trigger event can include a particular cardiac event indicative of a problem, e.g., a heart rate above or below a threshold amount, and / or a particular waveform characteristic.

[0068] Figures 4(a)-5(b) show various examples of devices having an array of sensors according to the present disclosure, for example, Figures 4(a)-(b) show an example of a device having four electrodes configured to interact with a user's skin.

[0069] 4(a) is a top (or bird's-eye) view of a device including a sensor array with four sensor circuits with four electrodes 447, 449, 451 and 453. Line widths and spacings are on the order of 0.1 mm to 20 mm for pulse monitoring. As shown, the sensor array includes optional ground connections 440, 458 and optional active shield connections 442, 448, 450 and 456. The array of sensors further includes sensor connections 444, 446, 452 and 454, and insulating layers 460 and 443.

[0070] FIG. 4(b) is a side view of the device shown in FIG. 4(a). As shown, the layers include an insulating layer 460, four electrodes 445 (e.g., electrodes 447, 449, 451, and 453 shown in FIG. 4(a)), and another insulating layer 443. The device includes an active portion (or region) 455 configured to be placed near or in contact with the skin of a user or other subject. The length of the active portion 455 is on the order of 0.1 mm to 20 mm or more for pulse monitoring. The active portion 455 may be in contact with the skin or may be spaced apart from the skin by a distance of up to 1 mm without contact. In various specific embodiments, the distance is typically less than 100 microns from the skin, which is sufficient to obtain a signal with a low enough signal-to-noise value to obtain heart rate and / or blood pressure. In specific embodiments, the electrodes 445 are non-planar or wavy for sensitivity purposes to reduce contact with the skin. The smaller the active area, the more sensitive it is, but the more difficult it is to position accurately.

[0071] In various embodiments, the device includes a packaged sensor array that includes (four) electrodes 445 configured to interact with the skin of a user. The sensor array (e.g., electrodes) may be packaged with an insulating material (e.g., a dielectric material) to provide environmental stability and moisture resistance. Insulating materials include polyester, polyolefin, fluoropolymer, polyimide, polyvinyl chloride, cellulose, paper, cloth, and other materials. The thickness of the packaging may be on the order of 5 to 250 microns or more. Similarly, the thickness of any adhesive and conductor layers is on the order of tens of microns, typically less than 70 microns for the adhesive and less than 5 microns for the conductor layers. The conductor layers are optional passive shielding layers and / or connected to control devices to provide active shielding.

[0072] In a specific embodiment, the layers include an optional shielding and adhesive coated insulating layer, an insulating layer, one or more electrodes, another insulating layer, and an optional shielding and another adhesive coated insulating layer, as further described with reference to Figures 5(a)-(b).

[0073] In some embodiments, the sensor array (e.g., electrodes) are packaged in an insulating material (e.g., a dielectric material) to provide additional environmental stability and moisture resistance. One or more insulating layers may be slit in one or more locations to mechanically isolate the individual sensor circuits and improve conformance of the packaged sensor to the underlying substrate.

[0074] In a further specific embodiment, the packaged sensor array comprises (four) electrodes 445 and a spacer layer. The spacer layer comprises one or more spacers that can set or adjust the distance of the sensor circuitry and / or electrodes (at least a part of them) from the skin surface, as already shown in FIG. 2(d). The spacer layer can minimize or mitigate stray capacitance from non-active (non-sensing) areas. The thickness of the spacer layer is on the order of 0.1 mm to 5 mm or more, as long as the distance does not affect the sensor sensitivity. The sensor array (e.g., electrodes) may be packaged in an insulating material (e.g., a dielectric material) to provide environmental stability and moisture resistance. The thickness of the packaging is on the order of 5 to 250 microns or more. Similarly, the thickness of any adhesive and conductor layers is on the order of tens of microns, typically less than 70 microns for the adhesive and less than 5 microns for the conductor layers.

[0075] The packaged sensor array further comprises a shielding layer. As described further below, one or more insulating layers comprise an adhesive coating on their inner surface and are adhered one to the other, e.g., an insulating layer is adhered to another insulating layer. The insulating layer comprises a conductor layer on its outer surface that contacts the user's skin. The conductor layer may be arranged to be sandwiched between two insulating layers. The conductive material may be, for example, aluminum, gold, carbon, or copper that is printed, evaporated, sputtered, or plated onto a non-conductive substrate (e.g., a PET or polyimide substrate). The insulating layer may be slit at one or more locations to mechanically separate the individual sensor circuits and improve the compatibility of the packaged sensor circuits with the underlying substrate. The substrate is thus constructed and arranged as a user accessory that conforms to the wrist, limb, or other body part of a user.

[0076] In a specific embodiment, insulating layers 443, 460 and electrodes 445 are formed from flexible flat cable (FFC / FPC) (e.g., commercially available Molex 15168-0147), insulating layer 460 with adhesive coating is formed from polyethylene terephthalate (PET) with adhesive (e.g., commercially available Avery 15660), insulating layer 443 with conductor layer is formed from 12 micron PET with vapor deposited aluminum of about 2 optical density or higher (e.g., commercially available Celplast Cel-Met 48g), and the spacer layer is formed from a layer of foam tape (e.g., commercially available Nexcare 731). The individual electrodes are 0.625 mm wide with 0.625 mm spacing between them.

[0077] Different electrodes 445 may have different capacitance sensitivities. The device includes a spacer layer that covers the active parts of some but not all of the sensors. The sensor circuits may have separate readout devices to prevent or mitigate crosstalk through common circuits.

[0078] The flexibility or flexing of the sensor circuits shown in this disclosure (including, for example, FIGS. 1(a)-(b), 2(a), (c)-(d), 4(a)-(b), 5(a)-(b), 6(b), and 16(a)) is sufficient to obtain a change in pressure or capacitance (e.g., a change in capacitance value). More specifically, the stiffness of the sensor is inversely proportional to the thickness and / or length of the sensor circuit (e.g., the thicker or longer the electrodes, the stiffer they are). The flexibility and thickness (and / or length) may be configured to correlate sufficiently to provide sensitivity to pressure changes of 0.3 kilopascals (kPa) to 1 kPa and / or capacitance changes of ±15 picofarads (pF) from a baseline capacitance of the sensor circuit. In more specific embodiments, the flexibility and thickness and / or length may be configured to correlate sufficiently to provide sensitivity to pressure changes of 0.5 kPa to 1 kPa. Further, as described herein, measurements of pressure changes indicative of capacitance changes are sensed when the sensor circuit is in contact with the skin or other surface, and the sensed capacitance changes are obtained when the electrodes are not in contact with (but are spaced up to 1 mm from) the user's skin or other surface.

[0079] 5(a)-(b) show an example of a device with a packaged sensor array with multiple (e.g., four) electrodes with different capacitance sensitivities. The device includes a spacer layer 545 that covers the active portions of some of the sensor circuits (e.g., electrodes 547 and 548), but not all of the sensor circuits (e.g., except for electrodes 549 and 550). Alternatively and / or additionally, some of the sensor circuits (e.g., electrodes 549 and 550) and parts of the insulating layers 541, 543 are shorter in length (relative to the edge of the device adjacent the active portion 551) than other sensors (e.g., electrodes 547, 548). The readout electronics may be separated in the sensor circuits to prevent or mitigate crosstalk through common circuits. As described above, one or more of the insulating layers 530 may include an adhesive coating on its inner surface to bond the insulating layer 530 to other layers, e.g., the insulating layer 530 to the other insulating layers 541, 544. Another insulating layer 544 includes a conductive layer on its outer surface that contacts the user's skin.

[0080] 5(a) shows a top (or bird's-eye) view of a device with four electrodes 547, 548, 549 and 550. As shown, the sensor array includes optional ground connections 531 and 540 and optional active shield connections 532, 535, 536 and 539. The sensor array further includes sensor connections 533, 534, 537 and 538, insulating layers 541 and 543, a spacer layer 545 and additional insulating layers 544 and 530 with optional shielding and adhesive coatings. The insulating layers 541 and 543 may be slit at one or more locations 542 to mechanically isolate the individual sensor circuits and improve the conformance of the packaged sensor to the underlying substrate.

[0081] Figure 5(b) is a side view of the device shown in Figure 5(a). As shown, the layers include an insulating layer 530 having an adhesive coating on its inner surface (e.g., the surface adjacent insulating layer 541), an insulating layer 541, four electrodes 546 (e.g., electrodes 547, 548, 549 and 550 in Figure 5(a)), another insulating layer 543, a spacer layer 545, and another insulating layer 544 having a conductive material on its outer surface (e.g., the surface opposite and / or not adjacent to spacer layer 545). The device includes an active portion 551 as described above.

[0082] 6(a)-(c) show a device according to the present disclosure. In a specific embodiment, as shown in FIG. 6(b) and (c), the device can include a flexible ribbon sensor array 602 configured and arranged to sense pulse waves. The flexible ribbon sensor array 602 is fitted and secured to a wristband 604 and wrapped around the wrist of a user 603, as shown in FIG. 6(c). The chart in FIG. 6(a) shows capacitance data for a characteristic radial artery pulse waveform 601. In an embodiment, a bandpass filter (20Hz / 0.5Hz) is used to process the data, and the measured heart rate is obtained, which is 71 bpm. The baseline heart rate (according to Fitbit Charge HR®) is 70 bpm, indicating that the sensor signal reflects the cardiac cycle. In this embodiment, the flexible ribbon sensor array 602 is secured by an elastic wristband 604, which makes uniform contact with the user's skin. Molex 15168-0147 FFC jumper cable can be used as the flexible ribbon sensor array in various embodiments. Heart rate can be calculated from the waveform data by Fourier transform. The flexible ribbon sensor array 602 can be connected to a Bluetooth proximity sensor circuit (e.g., an electrical signal sensing circuit).

[0083] FIG. 7 shows examples of data acquired using the device of, for example, FIG. 6(b)-(c) according to various embodiments. In certain embodiments, the device includes a ribbon cable implemented to allow multiple channels to be measured simultaneously (or alternatively, selectively, in parallel or sequentially) along different signal paths provided by the conductors of the cable. In such embodiments, different electrodes (and respective sensor circuits) are configured in any of a number of channels (e.g., signal paths) each carrying a signal for sequential processing by the electrical signal sensing circuitry and / or sequential or simultaneous processing by the electrical signal sensing circuitry. As an example of four channels being measured, the device includes four electrodes, one for each signal path / channel, as shown in FIG. 7(a). As in FIG. 6(a), a bandpass filter (20Hz / 0.5Hz) is used to extract data (e.g., from unfiltered data 705, 707, 709, 711 from the four channels). In this example, the measured heart rate is 71 bpm and the baseline heart rate (according to Fitbit Charge HR®) is 70 bpm. In this example, the flexible ribbon sensor array is secured by an elastic wristband to ensure uniform contact with the user's skin. Molex 15168-0147 FFC jumper cable can be used as the flexible ribbon sensor array in various embodiments. Heart rate can be determined from the waveform data by Fourier transform. The flexible ribbon electrodes can be connected to a Bluetooth proximity sensor circuit (e.g., an electrical signal sensing circuit).

[0084] Figure 8 shows example data 802, 804, 806, and 808 acquired using the device. In certain embodiments, the device can include an additional dielectric insulation layer (tape) to modify the signal to noise response. The top two charts (e.g., data 802, 804) show the response of an electrode without a dielectric insulation layer. The bottom two charts (e.g., data 806 and 808) show the response of an electrode with one dielectric insulation layer, showing a drop in signal amplitude.

[0085] 9A-9B show examples of devices with multiple channels and data acquired using the devices, according to various embodiments. One or more channels include or are associated with a dielectric layer that can reduce signal strength. FIG. 9A shows examples of data acquired using a device with four channels (e.g., signal paths in which electrodes are configured to carry respective signals). Signal amplitude can be reduced by one or two dielectric layers (e.g., one or two tapes) compared to direct contact. As shown, waveform 914 is data acquired using an electrode with no dielectric layer, waveform 915 is data acquired using an electrode with one dielectric layer, waveform 916 is data acquired using an electrode with two dielectric layers, and waveform 917 is data acquired using an electrode with no dielectric layer. The device used to collect the illustrated data includes a sensor strip and is mechanically connected to the user's skin, for example, via a wristband.

[0086] In certain embodiments, the dielectric layer modulates the amplitude of the pulse wave but does not prevent observation of baseline shifts due to unnatural components from movement or breathing. FIG. 9B shows data acquired using the above device in response to signal changes caused by a 6 inch up and down movement of a user's hand. As shown, each channel can be used to acquire observations of baseline shifts due to user movement, shown as waveforms 918, 919, 920 and 921, respectively. A sensor circuit with low sensitivity to pulse waveform signals (e.g., a sensor circuit with one or two layers of dielectric material) can serve as a reference to remove baseline shifts due to user movement in differential mode.

[0087] FIG. 10 shows examples of data acquired using a device according to various embodiments. Particular embodiments incorporate one or more electrodes (e.g., sensors) placed at various locations, e.g., on the front, back, and / or sides of the wrist. The location of the electrodes at different locations serves as a measure of the total motion artifact in differential mode. The locations are selected to mimic the motion artifact observed at the pulse point. FIG. 10 shows different data acquired with each electrode (e.g., organized as channels) of a device with four sensor circuits placed at different locations around the wrist. The acquired data is shown as waveforms 1003, 1005, 1007, and 1009. The sensor circuits are mechanically coupled to the user via a wristband.

[0088] In certain embodiments, the device is implemented with different types of electrodes. For example, Figures 11-15(b) show data acquired using different types of electrodes.

[0089] FIG. 11 shows an example of data acquired using a device with a single strip electrode with a planar contact point. The data 1129 shown in FIG. 11 is unfiltered. A bandpass filter (20Hz / 0.5Hz) is used to extract the data. In an example, the calculated HR is 63 bpm and the baseline HR (according to Fitbit Charge HR®) is 63 bpm. In this example, the copper tape electrode is 6 mm wide and 3 centimeters (cm) long, with a planar copper contact point against the user's skin and uniformly contacted to the user's skin by an elastic wristband, although the disclosure is not limited to this example. The electrodes are of various dimensions, e.g., widths ranging from 0.5 mm to 6 mm, widths ranging from 0.5 mm to 1 cm, and lengths ranging from 0.5 mm to 3 cm.

[0090] FIG. 12 shows an example of data acquired using a device according to various embodiments. As described above, the device includes at least one sensor circuit with an electrode, the corner of which is placed near the skin of the user. The corner contact is near the skin but not touching the skin of the user. The closer the corner contact is to the skin, the stronger the resulting signal will be. FIG. 12 shows an example of a pulse wave 1238 acquired using the device described above. The pulse wave 1238 shows the signal from the sensor circuit, and data 1234, 1236 and 1239 show the signal from a free signal channel where no sensor circuit is connected. In this example, the sensor circuit includes a 6 mm wide copper tape electrode with a corner contact.

[0091] 13(a)-(b) show examples of data acquired using a device according to various embodiments. The device includes a single electrode formed from a conductive fabric. For example, the fabric electrode is 2 mm wide and 2 cm long. FIG. 13(a) shows an example of a pulse wave 1350 acquired using a fabric electrode. The electrode can be laid flat on the user's skin and held on the skin by a wristband. The user's arm can be raised and bent, and data is acquired after the user steps. FIG. 13(b) is an example graph of heart rate 1354 over time, generated using the data of FIG. 13(a). A bandpass filter (20Hz / 0.5Hz) is used to process the pulse waveform data, the heart rate is calculated from the Fourier transform of the pulse wave, and the heart rate value is averaged over a period (e.g., 15 seconds). The reference data 1353 in this example lags the experimental data by a period (e.g., 30 seconds) due to the difference in the averaging period.

[0092] FIG. 14 shows an example of data acquired using a device according to various embodiments. The device includes a single (meshed) wire electrode. As shown, the acquired data includes a pulse wave 1457. To determine the heart rate, a bandpass filter (1 Hz / 2 Hz) is used to extract the heart rate data. In an example, the calculated heart rate is 71 bpm and the baseline heart rate (according to Fitbit Charge HR®) is 72 bpm. The electrodes are made of steel (e.g., steel picture wire) and secured by an elastic wristband.

[0093] 15(a)-(b) show an example of a device and data acquired using the device, according to various embodiments. As shown in FIG. 15(a), the electrodes 1559 have a more complex geometry, e.g., a star-shaped copper foil electrode that is placed flat on the user's skin and secured to the skin by a wristband. FIG. 15(b) shows examples of filtered and unfiltered pulse waves (e.g., unfiltered waveform 1561 and filtered waveform 1562) acquired using the device of FIG. 15(a). A bandpass filter (20Hz / 0.5Hz) is used to extract the data. In the example, the calculated heart rate is 71 bpm and the baseline heart rate (according to Fitbit Charge HR®) is 71 bpm.

[0094] Referring to the block diagram of FIG. 3, the signal flow from the body-worn transducer is converted for digital processing (performed by a microcontroller) and wirelessly (and / or wired) communicated to a remote user interface. In certain embodiments, the relevant signal is acquired by the sensor circuitry and processed and detected / measured by the transducer (e.g., capacitance-to-digital converter) and electrical signal sensing circuitry (e.g., a microcontroller), regardless of whether the transducer and / or sensor circuitry are initially configured to touch the user's skin (in the case of conductive transducers that rely solely on electrical conduction) and / or the particular type of interface between the user's skin and the transducer. Depending on the possible mechanisms described above, unlike existing sensor approaches, the present embodiment does not rely on the amount of initial contact with the user's skin and / or the type of interface (which are insensitive to changes in fringe area and / or small changes in distance between the electrodes and the skin). In various embodiments, the signal carried by the electrodes is not affected or altered by brightness changes due to hemodynamic or pulse wave events, as in, for example, photoplethysmography (PPG) sensors.

[0095] In various embodiments, a sensor circuit with a single electrode is used for proximity sensing. As described above, capacitance changes are conveyed through the electrodes and each sensor circuit and are responsive to pressure and / or electric field modulations resulting from hemodynamic or pulse wave events. The capacitance changes are due to changes in vascular pressure, geometry, or electric field distribution, but these parameters are not measured directly. The sensor circuit and electrodes obtain (or sense) the capacitance changes through proximity sensing of the user's skin (as opposed to physically deforming the device as a capacitance sensor), thereby functioning as or being a proximity sensor. The proximity sensor and / or capacitance changes are responsive to changes in distance between the user's skin and the sensor circuit and / or changes in the fringe area lines.

[0096] Various embodiments described above and in the detailed / exemplary embodiments further below refer to a user and a respective wearable device conforming to the skin or body of the user. Those skilled in the art will appreciate that the user is not limited to humans. In specific embodiments, the user includes a life form or animal (other than human), such as horses, dogs, cows, birds, reptiles, various animals monitored in zoos and other species of life forms or animals (e.g., zebras, elephants, pandas, etc.), life forms or animals monitored in the wild, and other life forms. The skin of the user (e.g., animal) may be covered with hair, and the wearable device conforms to or is mechanically constrained to the body of the user (e.g., animal).

[0097] Slides 17 and 18 of the provisional application entitled “Proximity Sensor and Related Sensing Method,” filed March 29, 2019 (Serial No. 62 / 314,474), illustrate in detail one example of how the sensor circuitry may be embodied in relation to a particular specific embodiment, and are incorporated herein in their entirety for teaching purposes.

[0098] (More specific examples) An embodiment of the present disclosure includes the use of a device comprising an electrical signal sensing circuit and at least one sensor circuit comprising electrodes to monitor capacitance and / or relative capacitance changes in response to changes in distance between each electrode and the user's skin and / or changes in electric field near the arterial pulse point caused by a pulse wave event. The changes in capacitance are used to determine pulse waves and / or pressure differences. The pulse waves are used to non-invasively determine various hemodynamic parameters and / or changes in parameters such as heart rate, diastolic blood pressure, systolic blood pressure, arterial wall stiffness, and blood volume.

[0099] FIG. 16 shows example data collected using devices according to various embodiments. The data includes a range of different shaped pulse waves 1664, 1665, 1666, 1667, 1668, 1669, 1670, 1671, 1672, 1673, 1674, 1675, 1676, and 1677 (collectively referred to below as "pulse waves" for ease of reference) that can be obtained using devices of the present disclosure. The illustrated pulse waves are obtained by measuring the relative change in capacitance and are not referenced to absolute capacitance values. However, embodiments of the present disclosure are not so limited.

[0100] 17(a)-(c) show examples of data acquired with a device and data collected with an arterial line, according to various embodiments. The data acquired with the device (placed near the user's left radial artery pulse point) tracks and / or mimics the data acquired with an arterial line implanted in the right radial artery. FIG. 17(a) shows data 1773 acquired with a device according to various embodiments mimicking data 1772 acquired with an arterial line. FIG. 17(b) shows data 1773 (e.g., waveforms) and FIG. 17(c) shows data 1772, which are separated for further illustration.

[0101] 18(a)-(c) show examples of pulse waves collected using a device and using an arterial line, according to various embodiments. Data acquired using the device (placed near the user's left radial artery pulse point) tracks and / or mimics data acquired using an arterial line implanted in the right radial artery. Heart rate can be determined by beat-to-beat analysis by measuring the pulse length. Heart rate variability is obtained from the distribution of individual heart rate values. FIG. 18(a) shows pulse waveform data 1877 acquired by the device mimicking pulse waveform data 1875 acquired using an arterial line. FIG. 18(b) shows pulse waveform data 1877 (e.g., waveform) and FIG. 18(c) shows pulse waveform data 1875, which are separated for further illustration.

[0102] 19(a)-(c) show examples of heart rate and blood pressure changes collected using a device and using an arterial line according to various embodiments. Heart rate and blood pressure patterns and abnormalities are followed and / or monitored in various embodiments. The patterns and / or abnormalities are indicative of various health conditions, such as fibrillation, high blood pressure, peripheral vascular disease, aortic regurgitation, aortic stenosis, and / or left ventricular failure, among others. Data acquired using a device (placed near the user's left pulse point) tracks and / or mimics data acquired using an arterial line implanted in the right radial artery. FIG. 19(a) shows data 1981 acquired using a device according to various embodiments mimicking data 1979 acquired using an arterial line. FIG. 19(b) shows data 1981 (e.g., waveforms) and FIG. 19(c) shows data 1979, which are separated for further illustration.

[0103] FIG. 20 illustrates an example of a respiratory rate collected using a device according to various embodiments, which may be used to measure and / or monitor respiratory rate from a respiratory mode. For example, FIG. 20 illustrates data 2087, 2088, 2089, and 2090 acquired using four different channels, showing periodic baseline shifts along with characteristic cycles associated with a user's respiratory motion.

[0104] FIG. 21 shows an example of data collected using a device with multiple electrodes positioned at different locations, according to various embodiments. As described above, the electrodes are positioned to have multiple channels, each carrying a signal for processing by the electrical signal sensing circuitry. The quality and amplitude of data acquired between the channels (which may be acquired simultaneously) may vary depending on the location of each electrode. FIG. 21 shows filtered data 2115, 2116, 2117, and 2118 (e.g., filtered raw data acquired using four channels).

[0105] FIG. 22 shows an example of data collected using a device with multiple electrodes placed at different positions, according to various embodiments. As previously described in conjunction with FIG. 21, the position of the electrodes affects the quality of the data acquired. Additionally and / or alternatively, the electrode positions may be a mixture of regular and inverse positions (respectively). FIG. 22 shows filtered data 2221, 2222, 2223, and 2224 acquired using four electrodes as described above.

[0106] FIG. 23 shows an example of data collected using a device with multiple electrodes, according to various embodiments. In various embodiments, data acquired using the electrodes can be processed using bandpass filters to reduce baseline drift and signal noise. For example, FIG. 23 shows filtered data 2345, 2346, 2347, and 2348 acquired using four identical channels (e.g., filtered using a 0.1 to 20 Hz bandpass filter).

[0107] As shown and described above, the pulse wave can be used to determine various hemodynamic parameters. For example, the shape and other characteristics of the pulse wave can be correlated to blood pressure. In other embodiments, heart rate and heart rate variability can be obtained by determining the timing of each pulse. Additionally, changes in blood pressure can be monitored by initially calibrating the data (e.g., calibrating the arterial line against an inflatable cuff).

[0108] Various techniques, including feature analysis and computational fluid dynamics, can be applied to analyze the pulse waves and / or determine various hemodynamic parameters. For example, features resulting from hemodynamic phenomena correlate with blood pressure, arterial stiffness, and other hemodynamic parameters. For more general and specific information on features resulting from hemodynamic phenomena, see JRSM Cardiovascular Disease 1.4(2012):cvd.2012.012016, PMC, Web, January 31, 2017; Cecelia, Marina, and Phil Chowienczyk, "Role of Arterial Stiffness in Cardiovascular Disease," Journal of Applied Physiology, Vol. 116, no. 11, 1396-1404, June 1, 2014; Baruch, Martin, David A. Donley et al., "Aerobic Exercise Training Reduces Arterial Stiffness in Metabolic Syndrome," Biomedical Engineering Online 13.1(2014):96. See, C et al., "Validation of Pulse Decomposition Analysis Algorithms Using Central Arterial Blood Pressure," and Munir, Shahzad et al., "Peripheral Augmentation Index Defines Relationship Between Central and Peripheral Pulse Pressure," Hypertension 51.1 (2008):112-118, both of which are incorporated herein in their entirety. As another example, the Augmentation Index (AI), (peripheral second systolic blood pressure (pSBP2)-diastolic blood pressure (DBP)) / peripheral systolic blood pressure (pSBP)-DBP), can be used as a marker of arterial wall stiffness and can be correlated with both peripheral and central peak blood pressures (pPP and cPP). AI is a normalized parameter and can be analyzed without absolute calibration. Computational fluid dynamics involves modeling the vasculature as an inductor-capacitor-resistor (LCR) circuit and / or a network of elastic pipes, with calculated parameters such as pulse wave velocity and / or waveform.For more general and specific information regarding computational fluid dynamics applied to the determination of hemodynamic parameters, see Lee, Byoung-kwon, "Computational Fluids in Cardiovascular Disease," Korean Journal of Cardiology 41.8 (2011):423-430, and Xiaoman Xing and Mingshan Sun, "Optical Blood Pressure Estimation Using Photoplethysmography and FFT-Based Neural Network," Biomed.Opt.Express7, 3007-3020 (2016), both of which are incorporated herein in their entirety. One model for obtaining the relationship between pulse waves (obtained by PPG) and blood pressure includes the following equation, where g is defined by the coefficient E of the vascular wall: E=E0e γP For example, the normalized waveform is given by: TIFF0007648197000001.tif115117

[0109] Various techniques are applied to correlate pulse waves with blood pressure values. For more general and specific information on techniques related to correlating pulse waves with blood pressure values, see Xing, Xiaoman, and Mingshan Sun, "Optical Blood Pressure Estimation Using Photoplethysmography and FFT-Based Neural Networks," Biomedical Optical Express 7.8 (2016):3007-3020, and http: / / cs229.stanford.edu / proj2014 / Sharath%20Ananth,Blood%20Pressure%20Detection%20from%20PPG.pdf, both of which are incorporated herein in their entirety.

[0110] 24(a)-(b) show examples of pulse waves generated using a wearable device, an arterial line, and an optical sensor, according to various embodiments. The wearable device includes a sensor circuit with electrodes, as described above.

[0111] As shown in Fig. 24(a), the pulse wave 2455 generated using the wearable device captured the secondary features, especially when the secondary features were large and far from the main peak, and is similar to the pulse wave 2457 generated using an arterial line and the pulse wave 2459 generated using an optical sensor (e.g., photoplethysmography (PPG)).

[0112] 24(b) illustrates the ability of the electrical signal sensing device to capture small features of a pulse wave 2460 whose waveform can be correlated to blood pressure. The features can be removed by a PPG sensor, as shown in pulse wave 2464 acquired using PPG, with portions of pulse waves 2460, 2462 and 2464 highlighted by circles.

[0113] Orientation and direction terms, such as upper / lower, left / right, top / bottom, upper / lower, upward / downward, vertical, horizontal, and orthogonal, are used herein to describe the relative positions of components in the drawings. Similarly, heating and cooling are relative terms in the art, and heating and cooling sources are synonymous, recognizing that the direction of temperature change can be controlled depending on the desired temperature change. The terminology is used for convenience of notation only, and in actual use, the disclosed configurations may be oriented differently than shown. Thus, the terminology should not be construed as limiting.

[0114] It is also useful to appreciate the background / meaning of the following terms: The term "electrode" refers to or includes an electrical conductor. The term "sensor circuit" refers to or includes a circuit comprising an electrode and a connection to a transducer circuit (e.g., comprising a sensor connector for the electrode to plug in or otherwise connect to the transducer circuit) that detects or measures capacitance values ​​and / or capacitance changes via the electrode and outputs the same to the transducer circuit, the sensor circuit additionally comprising various components such as those shown in Figures 4(a)-(b) and 5(a)-(b), for example, the sensor circuit may comprise a multi-layer configuration comprising an electrode and various dielectric and conductor layers. The term "transducer circuit" refers to or includes a circuit that converts a change in a physical quantity, e.g., a capacitance change provided by the sensor circuit, into an electrical signal, for example, the transducer circuit may comprise a capacitance-to-digital converter. The term "pulse wave event" refers to or includes a hemodynamic response and / or cause (e.g., heart beat or heart sounds, changes in blood pressure or blood flow velocity) caused and / or indicative of a beating of the heart (e.g., contraction of the myocardium), and the term "pulse wave" refers to or includes a signal or waveform generated by a pulse wave event, an example of a pulse wave being an arterial pulse wave, e.g., a waveform generated by the heart when it contracts and the wave travels along the arterial wall of the arterial tree. The term "electrical signal sensing circuitry" refers to or includes circuitry used to sense hemodynamic or pulse wave events using electrical signals from transducer circuitry, an example of an electrical signal sensing circuitry includes a microcontroller or other processing circuitry, an example of a transducer circuitry includes, but is not limited to, a capacitance-to-digital converter. The term "communication circuitry" refers to or includes circuitry that outputs data to other external circuitry, including wireless or wired communication. An example of a communication circuitry includes, but is not limited to, a transceiver.The terms "hemodynamics" or "hemodynamic parameters" refer to or include parameters related to blood flowing through organs, blood vessels, and tissues of the body, and examples of hemodynamics or hemodynamic parameters may include diastolic blood pressure, systolic blood pressure, arterial wall stiffness, blood volume, and other parameters.

[0115] Various embodiments are embodied in the underlying provisional application entitled "Proximity Sensor and Related Sensing Method" (Application No. 62 / 314474), filed March 29, 2016, which claims the benefit of and is incorporated herein by reference in its entirety. For example, the embodiments in this specification and / or the provisional application (including the slides therein) can be combined in various ways (including all combinations). Reference can also be made to the teachings of the experiments and underlying suggestions in the underlying provisional application and the slides forming part of said provisional application. The embodiments shown in the slides are in no way intended to be limiting to the entire disclosure or any portion of the claimed invention, unless otherwise specified.

[0116] Various blocks, modules, or other circuits may be implemented to perform one or more of the functions or operations described herein and / or illustrated in the figures. For example, processes such as heating, etching, deposition, etc. may be performed automatically using various circuits and associated equipment. In this context, various described functions are implemented using circuits that perform one or more of these or related functions / operations. In various embodiments, hardwired control blocks may be used to minimize area for the implementation when limited flexibility is sufficient. Alternatively and / or additionally, in certain of the above embodiments, one or more of the modules are discrete logic circuits or programmable logic circuits that are constructed and arranged to implement those functions / operations.

[0117] For example, the specification has described and / or illustrated aspects useful for implementing the claimed disclosure by way of or using various circuits or circuit configurations, which may be illustrated as blocks, modules, devices, systems, and / or other circuit-type representations. The circuits and circuit configurations are used in conjunction with other components (e.g., wristbands, external processing circuits, etc.) to illustrate how certain embodiments may be implemented in terms of structures, steps, functions, acts, operations, etc. For example, in certain of the above embodiments, in this context, one or more illustrated elements may represent circuits (e.g., discrete logic circuits or (semi-)programmable circuits) that are configured and arranged to perform these acts / operations, as in the approaches illustrated in the slides. In certain embodiments, the illustrated elements represent one or more computer circuits (e.g., microcomputers or other CPUs) that are understood to include memory circuitry that stores code (programs executed as a set / sets of instructions) for performing basic algorithms (e.g., monitoring pressure differentials and / or capacitance changes due to pulse wave events) and / or determining hemodynamic parameters, and / or more complex processes / algorithms. This is understood from the public knowledge that describes the particular parameter sensing. The processes / algorithms are specifically implemented to perform the relevant steps, functions, acts and operations as appropriate for the particular application. This specification also refers to adjectives (first [type of configuration] and second [type of configuration]) that do not imply a compositional contribution, but in this case the adjectives are used only as antecedents in English to distinguish one similarly named composition from another similarly named composition (e.g., "first electrode" is interpreted as "electrode").

[0118] Based on the above description and illustrations, it will be apparent to one skilled in the art that various applications and modifications can be made to the various embodiments without strictly adhering to the exemplary embodiments and applications disclosed and illustrated herein. For example, the methods illustrated in the figures include steps performed in various orders, but may include the same, fewer, or more steps in one or more aspects of the embodiments. Such applications do not depart from the spirit or scope of the various aspects of the present disclosure, including those aspects described in the claims.

Claims

1. A transducer circuit has a plurality of sensor circuits that are capacitance sensors and converts a change in capacitance into an electrical signal; an electrical signal sensing circuit that monitors a change in the capacitance in response to the electrical signal from the transducer circuit; a substrate supporting the transducer circuitry and the electrical signal sensing circuitry so as to at least partially surround the transducer circuitry and the electrical signal sensing circuitry; a communication circuit for transmitting data from the electrical signal sensing circuit; Equipped with each of the plurality of sensor circuits includes a single electrode and a dielectric layer added to a portion or surrounding the electrode to sense the change in capacitance; At least one of the plurality of sensor circuits senses a change in the capacitance responsive to a change between the user's skin and the single electrode due to hemodynamic changes capable of correlating a waveform to blood pressure; the change between the user's skin and the single electrode includes at least one of a pressure change due to the hemodynamic change and an electric field modulation due to the hemodynamic change; the hemodynamic change corresponds to at least one of one or more pulse wave shape features away from a major peak and one or more changes in pulse wave shape; the electrical signal sensing circuitry is positioned relative to the user's skin to monitor the change between the user's skin and the single electrode, regardless of an amount of initial contact between the single electrode and the user's skin, and senses the hemodynamic change in response to the electrical signal from the transducer circuitry; the electrical signal sensing circuit monitors the change between the user's skin and the single electrode according to a pressure difference of less than 1 kilopascal (kPa) and / or a change in capacitance of the order of 15 picofarads (pF) with a maximum offset of the change in capacitance of less than 100 pF; Wearable devices.

2. The wearable device of claim 1 , wherein the plurality of sensor circuits are arranged in an array such that one or more of the plurality of sensor circuits are mechanically isolated from others of the plurality of sensor circuits.

3. The wearable device of claim 1 , wherein the plurality of sensor circuits are arranged such that the electrodes of each of the plurality of sensor circuits are differently designed and located at different positions on the wearable device to improve position accuracy.

4. The wearable device of claim 1 , wherein the multiple sensor circuits are arranged such that the electrodes of each of the multiple sensor circuits are differently designed and located at different positions on the wearable device to provide multiple reference signals for different analyses.

5. 2. The wearable device of claim 1, wherein the plurality of sensor circuits operate in a power saving mode in which power consumption by the wearable device does not exceed a threshold amount in the range of between 5 microwatts and 3 milliwatts by burst transmitting stored data from the wearable device in response to one or more trigger events associated with one or more heart rates of a user of the wearable device, rather than storing data prior to the one or more trigger events, and by storing data including the one or more trigger events.

6. the plurality of sensor circuits operate by obtaining data corresponding to one or more trigger events associated with one or more heart rates of a user of the wearable device, and reducing power consumption by storing data including the one or more trigger events in response to the one or more trigger events rather than storing data prior to the one or more trigger events; The one or more trigger events may include a heart rate detected as being above a threshold, and one or more corresponding heart rate related events detected as indicative of a problem. The wearable device according to claim 1 .

7. In operation, the single electrode conveys a capacitance change upon proximity sensing of the user's skin that differs from a physical deformation; changes in arterial pressure adjacent the single electrode are measured as changes in the capacitance and cause changes in the fringe area lines corresponding to the changes in capacitance. The wearable device of claim 1 .

8. 2. The wearable device of claim 1, wherein the plurality of sensor circuits are arranged in an array such that at least one of the plurality of sensor circuits functions as a proximity circuit and the single electrode is associated with each of the at least one of the plurality of sensor circuits to convey the change in capacitance via proximity sensing of the user's skin that is distinct from a response to a physical deformation.

9. The wearable device of claim 1 , wherein for each of the plurality of sensor circuits, the single electrode is positioned near an arterial pulse point to measure an arterial pulse wave via the change in capacitance.

10. 2. The wearable device of claim 1, wherein for each of the plurality of sensor circuits, the single electrode is positioned near an arterial pulse point to measure arterial pulse waves via changes in capacitance without mechanically coupling to the user's skin.

11. The wearable device of claim 1 , wherein at least one of the sensor circuits has a different design than at least one other of the plurality of sensor circuits.

12. The wearable device of claim 1 , wherein the single electrode has dimensions ranging from 0.5 mm to 3 cm in length, the other two ranging from 0.5 mm to 6 mm and 0.5 mm to 1 cm.

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