Proximity Sensor Circuit and Associated Sensing Method

Abstract

The present disclosure relates to a proximity sensor circuit and related sensing methods. Various embodiments include devices and methods using a proximity sensor. Example devices include: a transducer circuit having a sensor circuit that includes electrodes; an electrical signal sensing circuit; a substrate that supports and at least partially encloses the transducer circuit and the electrical signal sensing circuit; and a communication circuit. The transducer circuit converts a change in capacitance, which is carried by the electrodes and responsive to pressure and / or electric field modulation caused by a hemodynamic or pulse wave event, into an electrical signal. The electrical signal sensing circuit senses an event in response to the electrical signal from the transducer circuit. The substrate may mate with a portion of a user and position the sensor circuit close enough to the user's skin to inductively sense a hemodynamic or pulse wave event. The communication circuit responds to the electrical signal sensing circuit by transmitting data indicative of hemodynamic monitoring.

Description

[0001] This application is a divisional application of the application with PCT international application number PCT / US2017 / 024838, international filing date of March 29, 2017, and Chinese national phase application number 201780022422.0, titled "Proximity Sensor Circuit and Related Sensing Methods".

[0002] Overview

[0003] Aspects of various embodiments relate to proximity sensors for sensing hemodynamic changes (or pulse waveforms) of a user and related sensing methods.

[0004] In the following discussion, various embodiments and applications are disclosed by way of non-limiting example embodiments to provide an understanding of the current disclosure.

[0005] In certain example embodiments, aspects of the present disclosure relate to one or more sensor circuits configured and arranged to sense hemodynamic changes (or pulse waveforms) of a user, and the sensor circuits are configured in a manner to monitor physiological changes of the user by using a single electrode placed near / on the surface to be measured. These and other aspects employ a sensor circuit configured to sense hemodynamic changes consistent with one or more of the embodiments and / or mechanisms described below.

[0006] More specific example embodiments relate to a device having at least one sensor circuit that includes an electrode and an electrical signal sensing circuit. The device can be used to non-invasively and in real-time monitor one or more hemodynamic parameters. For example, the electrical signal sensing circuit can sense pulse wave events by monitoring capacitance changes when the sensor circuit is placed near or on the skin. The capacitance change carried by the electrode responds to pressure and / or electric field modulation caused by pulse wave events or to changes in pressure or blood flow in blood vessels (e.g., hemodynamics). The electrode can be used to determine the capacitance change between the electrode and the user's skin. The sensor circuit including the electrode can be arranged together with a transducer circuit that is used to provide an electrical signal indicating changes in capacitance and / or pressure to the electrical signal sensing circuit. Due to pulse wave events, the distance between the user's skin and the electrode may change and / or the electric field distribution around blood vessels may change, which results in a relative change in capacitance when measurements are made using the sensor circuit. The change in capacitance over time can be processed by the electrical signal sensing circuit and can be used to generate and / or determine a pulse waveform. In various embodiments, the pulse waveform is related to various hemodynamic parameters. As a specific example, the pulse waveform can be processed to determine heart rate, blood pressure, arterial stiffness, and / or blood volume.

[0007] The electrode can be in contact with and / or close to the user's skin. In some aspects, mechanical constraints (e.g., wristbands, elastic compliant rings, or clothing) and / or adhesives are used to constrain the electrode to the user (whether in contact or not). The electrode can be positioned near a blood vessel, preferably near a palpable pulse point (such as but not limited to the pulse points of the radial artery, brachial artery, carotid artery, tibial artery, and temporal artery).

[0008] In other specific aspects, the device includes a plurality of electrodes. For example, the device can include a plurality of sensor circuits, and each sensor circuit includes one of the plurality of electrodes. The plurality of electrodes can be arranged as part of a transducer circuit that provides an electrical signal (e.g., a digital signal) indicative of a change in capacitance to an electrical signal sensing circuit, the change in capacitance being responsive to a modulation of the distance, pressure, and / or electric field between the user's skin and the electrode and being caused by a hemodynamic or pulse wave event. In various related aspects, the plurality of sensor circuits are mechanically separated and / or arranged in an array (e.g., a sensor array). Each sensor circuit can be constructed differently, such as having different geometric dimensions, dielectric layers, positions, sensitivities, and other configurations as further described herein.

[0009] Various aspects relate to methods of using the devices described above. The method can include placing at least one electrode of the device near or on the user's skin and sensing a pulse wave event. When at least one electrode is placed near or on the user's skin, a pulse wave event can be sensed using the electrical signal sensing circuit of the device and by monitoring a change in capacitance responsive to a modulation of pressure and / or electric field caused by a hemodynamic or pulse wave event. The pulse wave event can be used to generate a pulse waveform and / or to determine various hemodynamic parameters. For example, the method can include using the pulse wave event to determine diastolic blood pressure, systolic blood pressure, arterial stiffness, and / or blood volume.

[0010] Specific methods can include using a flexible or bendable substrate of a wearable device to protect a transducer circuit having at least one sensor circuit. The substrate supports and at least partially encloses the transducer circuit and the electrical signal sensing circuit. The substrate further mates with a portion of the user's body including a blood vessel and positions at least one electrode close enough to the user's skin to inductively sense a hemodynamic or pulse wave event via a change in capacitance, the change in capacitance being responsive to a modulation of pressure and / or electric field caused by a hemodynamic or pulse wave event. The transducer circuit converts the change in capacitance into an electrical signal. The method further includes: sensing a hemodynamic or pulse wave event via the electrical signal sensing circuit in response to the electrical signal from the transducer circuit; and using a communication circuit located inside or outside the wearable device to respond to the electrical signal sensing circuit by sending hemodynamic monitoring data to an external circuit.

[0011] Other aspects relate to a device for use as part of a wearable device, the device being characterized by a flexible or bendable substrate configured and arranged to support and at least partially enclose a transducer circuit and an electrical signal sensing circuit and to mate with a portion of a user including a blood vessel for hemodynamic monitoring. The device includes a transducer circuit having at least one sensor circuit, the sensor circuit including electrodes, an electrical signal sensing circuit, and a communication circuit, as previously described above.

[0012] The foregoing discussion / overview is not intended to represent every embodiment or every implementation of the present disclosure. The following figures and detailed description also illustrate various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The example embodiments may be more fully understood in consideration of the following detailed description in conjunction with the accompanying drawings, in which:

[0014] Figure 1A-1B An example of a device according to the present disclosure is shown;

[0015] Figure 2A-2D An example of a device according to the present disclosure and the resulting interaction with a user's skin are shown;

[0016] Figure 3 is a block diagram illustrating an example method for implementing an electronic device and / or signal flow from a device according to the present disclosure;

[0017] Figure 4A-5B Examples of various devices according to the present disclosure are shown;

[0018] Figure 6A-6C A device according to the present disclosure is shown;

[0019] Figure 7 Examples of data captured using a device (such as Figure 6B-6C the device shown) according to various embodiments are shown;

[0020] Figure 8 Examples of data captured using a device according to the present disclosure are shown;

[0021] Figure 9A-9B An example device having multiple channels according to the present disclosure and data captured using the device are shown;

[0022] Figure 10 Examples of data captured using a device according to the present disclosure are shown;

[0023] Figure 11 Examples of data captured using a device having electrodes with planar contact according to the present disclosure are shown;

[0024] Figure 12 Shows example data captured using a device according to the present disclosure;

[0025] Figure 13A-13B Shows example data captured using a device according to the present disclosure;

[0026] Figure 14 Shows example data captured using a device according to the present disclosure;

[0027] Figure 15A-15B Shows an example device according to the present disclosure and data captured using the device;

[0028] Figure 16 Shows an example of data collected using a device according to the present disclosure;

[0029] Figure 17A-17C Shows example data collected using a device according to various experimental embodiments and data collected using an arterial line;

[0030] Figure 18A-18C Shows example data collected using a device according to various experimental embodiments and data collected using an arterial line;

[0031] Figure 19A-19C Shows examples of changes in heart rate and blood pressure collected using a device according to various experimental embodiments and data collected using an arterial line;

[0032] Figure 20 Shows an example respiratory rate collected using a device according to various experimental embodiments;

[0033] Figure 21 Shows example data collected using a device having multiple electrodes according to various experimental embodiments;

[0034] Figure 22 Shows example data collected using a device having multiple electrodes located at different positions according to various experimental embodiments;

[0035] Figure 23 Shows example data collected using a device having multiple electrodes according to various experimental embodiments; and

[0036] Figure 24A-24B Shows example pulse waveforms generated using a wearable device, an arterial line, and an optical sensor according to various embodiments.

[0037] While the embodiments discussed herein may be subject to modification and alternative forms, aspects thereof have been shown by way of example in the drawings and will be described in detail. However, it should be understood that the invention is not limited to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure including aspects defined in the claims. Additionally, the term "example" as used throughout this application is for illustrative purposes only and not limiting. Detailed Description

[0038] Aspects of the present disclosure are believed to be applicable to a variety of different types of devices and methods, the device including a user-wearable sensor circuit and the method involving the use of a user-wearable sensor circuit configured and arranged to sense aspects, conditions, and / or properties of a user's pulse wave event. In certain embodiments, aspects of the present disclosure have been shown to be advantageous when used in the context of a wrist-mounted or wrist-worn band, but it will be understood that the present disclosure is not necessarily limited thereto. The various aspects may be understood through the following discussion of non-limiting examples using exemplary scenarios.

[0039] Accordingly, various specific details are set forth in the following description to describe specific examples presented herein. However, it will be apparent to one of ordinary skill in the art that one or more other examples and / or variations of these examples may be practiced without all of the specific details given below. In other instances, well-known features have not been described in detail so as not to obscure the description of the examples herein. For ease of illustration, the same reference numerals may be used in different figures to indicate the same element or additional instances of the same element. Additionally, although aspects and features may be described in the context of various figures in some cases, it will be understood that features from a figure or an embodiment may be combined with features from other figures or embodiments, even if the combination is not explicitly shown or explicitly described as a combination.

[0040] Various example embodiments of the present disclosure relate to a device including 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 and in real time monitor one or more hemodynamic parameters and pulse wave events. Surprisingly, it has been found that a single electrode with a common floating ground and not requiring contact with the user's skin can be used to measure pulse wave events. In various embodiments, pulse wave events can be monitored in a hands-free manner and without interference from ambient noise (such as human voices and other background noises, electrical interference, and ambient light). The electrode (or an array of electrodes) can consume a relatively low amount of power (e.g., between 5 microwatts and 3 milliwatts, although embodiments are not limited thereto). In some specific embodiments, power consumption can be reduced by saving data and / or transmitting the saved data in burst transmission only after a trigger event (such as a heart rate above a threshold, a specific cardiac event occurring (such as an event indicating a problem)). When at least one sensor circuit is placed near or on the skin, the electrical signal sensing circuit can sense pulse wave events by monitoring the pressure difference caused by the pulse wave event or the capacitance change caused by the pulse wave event. The electrode can be used to determine the capacitance change between the electrode and the user's skin. Due to the pulse wave event, the distance between the user's skin and the electrode may change, which results in a relative change in capacitance and / or the signal amplitude and quality measured by the transducer circuit and the electrical signal sensing circuit. The change in capacitance over time can be processed by the electrical signal sensing circuit and can be used to generate and / or determine a pulse waveform. In various embodiments, the pulse waveform is related to various hemodynamic parameters. As a specific example, the pulse waveform can be processed to determine heart rate, blood pressure, arterial stiffness, and / or blood volume. The electrode can be in contact with and / or close to the user's skin. In some embodiments, the electrode can be close enough to the user's skin to inductively sense hemodynamic or pulse wave events via the capacitance change carried by the electrode (or electrodes). In such an example, "close enough" corresponds to a close distance relative to the part including blood vessels in the range from a maximum distance of 1 millimeter (mm) from the skin to a minimum distance of zero or in contact with the skin. In some aspects, the sensor circuit (such as the electrode) is constrained to the user (whether in contact or not) using mechanical constraints (such as a flexible or bendable substrate, such as a wristband, sock, glove, sleeve, or other piece of device or clothing) and / or adhesives.

[0041] Changes in capacitance carried by an electrode and a corresponding sensor circuit respond to pressure and / or electric field modulation caused by hemodynamic or pulse wave events. More specifically, the sensor circuit and the electrode can capture (or sense) capacitance changes through proximity sensing of the user's skin (as opposed to physically deforming the device as in a traditional capacitance sensor), and thus function as or serve as a proximity sensor. Proximity sensing and / or capacitance changes respond to modulating the distance between the user's skin and the sensor circuit and / or modulating fringe field lines.

[0042] In other specific embodiments, the device includes a plurality of electrodes. The plurality of electrodes can be arranged as part of a transducer circuit that provides an electrical signal indicative of capacitance and / or pressure changes to an electrical signal sensing circuit. For example, the transducer circuit can include a plurality of sensor circuits, and each sensor circuit includes one of the plurality of electrodes. The electrical signal sensing circuit can be arranged together with the transducer circuit to monitor a pressure difference of less than 1 kPa (such as in the range of 0.3 kilopascals (kPa) to 1 kPa). Different electrodes can have different geometric dimensions, sensitivities, and / or be located at different positions. The transducer circuit converts changes in capacitance into an electrical signal (e.g., a digital signal). As described herein, the transducer circuit and the electrical signal sensing circuit can be supported and at least partially enclosed by a substrate.

[0043] Certain embodiments of the present disclosure relate to methods of using a device as previously described. The method can include placing at least one electrode of the device near or on the user's skin and sensing a pulse wave event. When at least one electrode is placed near or on the user's skin, the electrical signal sensing circuit of the device can sense the pulse wave event by monitoring the pressure difference caused by the pulse wave event and / or monitoring the capacitance change (or relative capacitance change) caused by the pulse wave event. The pulse wave event can be used to generate a pulse waveform and / or to determine various physiological parameters and / or hemodynamic parameters. For example, the method can include using the pulse wave event to determine diastolic blood pressure, systolic blood pressure, arterial stiffness, and / or blood volume.

[0044] Somewhat surprisingly, one or more electrodes placed on or near an arterial pulse point can be used to monitor pulse wave events. For example, in response to a pulse wave event, each electrode can provide a signal indicative of the pulse wave event. The electrode(s) is / are connected to a circuitry system (such as a transducer circuit). More specifically, each electrode (e.g., an electrical conductor) is connected to a respective sensor circuit that is configured to measure or detect a signal indicative of a pulse wave event from the electrode (e.g., a capacitance value and / or a change in capacitance) and provide that signal to the transducer circuit. The transducer circuit then converts the signal indicative of the pulse wave event into an electrical signal that is provided to an electrical signal sensing circuit. Pulse wave events include or refer to hemodynamic responses and / or properties (such as heartbeats or heart sounds, pulsations of blood, etc.) indicative of or caused by a heartbeat (e.g., contraction of the heart muscle). The electrical signal sensing circuit (and / or the transducer circuit) can include off-the-shelf or custom-designed circuitry for a capacitive touchscreen and can communicate wirelessly or wired to a central processing unit (CPU). Additionally, the transducer and / or the sensing circuit can have a floating ground. The signals measured using the electrodes can be attributed to small pressure differences and / or surface displacements of the skin that modulate the fringe field at the electrode and result in a measurable change in capacitance. The (multiple) electrodes can be attached to the skin of a user (or other animal or living being) using an adhesive (e.g., tape) or mechanically using a strap (such as a watchband, bracelet, or wristband).

[0045] In certain embodiments, a dielectric layer (e.g., a sealing material) is utilized to encapsulate the (multiple) electrodes. When multiple electrodes are used, the dielectric layer on each of the multiple electrodes can have different structural properties to modulate the signal sensitivity of each electrode. Example properties can include the thickness of the dielectric layer, the composition, structure, and resistivity value of the dielectric material used, as well as other properties. Each of the multiple electrodes can be associated with different properties based on at least one of the electrode geometry and the dielectric layer used with the electrode. In response to the monitored pulse wave events, different electrodes can be used to output signals. The signals from different electrodes can be used in a differential mode to cancel signals that may be common to the electrodes (such as temperature variations and user movement (e.g., noise)) and to enhance signals or pulse wave events (such as pulse waveform pressure differences) that can be measured by more sensitive electrodes. In related particular embodiments, one or more of the multiple electrodes can be electrically shielded or isolated from each other. Additionally, spacers can be used to control or set the distance between at least one of the sensor circuit and / or the electrode and the skin of the user.

[0046] Signals provided by the (multiple) electrodes can be used to determine various hemodynamic parameters. For example, in response to a pulse wave event, one or more signals indicative of a change in capacitance are provided to an electrical signal sensing circuit. As previously described, the change in capacitance borne by at least one electrode is responsive to pressure and / or electric field modulation caused by 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 stiffness. One or more band-pass filters or other signal processing techniques can be used to process the signals. For example, the signals can be filtered digitally or through circuit design for minimizing artifacts attributable to various factors such as pressure changes or motion due to respiration, arm movement, and external vibrations.

[0047] These surprising findings are particularly useful for monitoring blood pressure or other hemodynamic parameters in a non-invasive and / or continuous manner. In certain embodiments, a device can be used to provide sensitivity to pressure differences and / or capacitance changes caused by pulse wave events. Additionally, compared to capacitive sensors, the device and / or parts of the device (e.g., electrodes) can be more easily manufactured as they have fewer design elements and materials, making the end device more robust.

[0048] In a related particular embodiment, the device includes or can be a portable / wearable device and / or part of a device that continuously monitors heart rate and other hemodynamic effects such as diastolic blood pressure, systolic blood pressure, and arterial stiffness. As an example, a smart bandage can be applied at an arterial pulse point and can transmit data to a receiver in real time. Another example includes a smart watchband that provides real-time readout, storage, and / or transmission of data. Other embodiments relate to small surface displacements or pressure differences that can modulate the fringe field at the electrode.

[0049] Turning now to the drawings, Figure 1A-1B an example of a device according to the present disclosure is shown. As Figure 1A-1B shown, each device includes a sensor circuit having electrodes and an electrical signal sensing circuit. The device can monitor pressure differences and / or capacitance changes caused by pulse wave events and use the monitored pressure differences and / or capacitance changes to determine one or more hemodynamic parameters. A pulse wave event can be used to generate a waveform or a portion of a waveform (e.g., a tactile palpation representing a heartbeat) responsive to or indicative of the pulse of a user or animal. A pulse wave event can be captured as a signal, and the pulse wave event can be used to determine hemodynamic parameters such as heart rate, diastolic blood pressure, systolic blood pressure, and / or arterial stiffness.

[0050] Figure 1AAn example device is shown that includes a sensor circuit 103 having an electrode 102 and an electrical signal sensing circuit 106. The electrode 102 can be 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 a pulse wave event when the electrode 102 is placed near or on the skin of the user. In some embodiments, as further shown herein, the electrode 102 can be in direct contact with the skin or can be electrically or mechanically isolated from the skin (such as by air or a dielectric material). The electrode 102 is used to sense pressure and / or capacitance changes caused by a pulse wave event and outputs a signal indicative of the sensed pressure or capacitance change to the electrical signal sensing circuit 106 via the sensor circuit 103 and a communication path 104 (e.g., connecting or inserting the electrode to the sensor circuit 103, which captures and outputs a signal indicative of the capacitance value). The electrical signal sensing circuit 106 monitors the change in pressure or capacitance (or relative capacitance change) caused by a pulse wave event and determines hemodynamic parameters (such as heart rate) therefrom. The change in pressure and / or capacitance can be measured based on the relative change in capacitance, which can be caused by a change in the distance between the electrode 102 and the skin of the user and / or a change in the electric field around the blood vessel.

[0051] In a particular embodiment, the sensor circuit 103 and / or the 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 can be via an elastic, flexible, or bendable band and / or an adhesive that attaches the sensor circuit 103 and / or the electrode 102 to the skin or body. The adhesive can be applied to the perimeter 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 (such as via a spacer or otherwise), as further described herein. The capacitance change of interest can be relative and not an absolute value. The base capacitance of the electrode 102 can depend on the respective geometric dimensions and extents of the electrode 102 and / or the sensor circuit 103 design. In an example experimental embodiment, the electrical signal sensing circuit 106 can measure an input range (e.g., capacitance change) of plus or minus 15 picofarads (pF) with a maximum offset of 100 pF. The base capacitance can be on the order of 5 - 75 pF, and the pulse waveform signal obtained (by a pulse wave event) can have a maximum amplitude on the order of 0.1 to 1 pF. However, the embodiments are not limited thereto, and these values can be modified for different applications through sensor and electronics design.

[0052] The relative change of capacitance over a period of time can be used to generate and / or otherwise output a pulse waveform signal. The pulse waveform signal can indicate hemodynamic parameters and / or can include an arterial pulse wave (or sometimes referred to as an "arterial pressure wave"). The change in capacitance caused by a pulse wave event can be used to determine hemodynamic parameters (such as various hemodynamic parameters). As can be understood by one of ordinary skill in the art, an arterial pulse waveform is a waveform generated by the heart when the heart contracts and the wave travels along the arterial walls of the arterial tree. Generally speaking, the wave has two main components. The forward moving wave and the reflected wave. The forward wave is generated when the heart (ventricle) contracts during systole. This wave travels from the heart along the large aorta and is reflected into the two iliac vessels at the bifurcation or "crossroads" of the large arteries. In a normal healthy person, after the aortic valve closes, the reflected wave can return during diastole. The returning wave has a notch, and because it pushes blood through the coronary vessels, it also helps with the perfusion of the heart through the coronary vessels. The speed at which the reflected wave returns becomes very important: the stiffer the artery, the faster the reflected wave returns. This can then enter the systole and increase the final blood pressure reading. The arterial pulse wave travels faster than the ejected blood. It can be modified in various ways Figure 1A the example device shown (such as Figure 1B shown), such as Figure 1B shown. One example modification includes modifying electrode 102 to be electrically insulated from the user's skin. Electrode 102 can be insulated by adding a dielectric layer to a portion of electrode 102 and / or surrounding (e.g., encapsulating) electrode 102. In some particular embodiments, electrode 102 can be connected to a circuit system (e.g., a sensor circuit, such as a circuit board or a chip) included in a wristband. Electrode 102 can be flexible. For example, when the user wears the wristband, electrode 102 can bend around the wristband and be hidden within the wristband. In other examples and / or additionally, electrode 102 can be integrated and / or embedded into the wristband. The dielectric layer can be formed of different dielectric (or insulating) materials, such as polyester (e.g., polyethylene terephthalate), polyolefin, fluoropolymer, polyimide, polyvinyl chloride, cellulose, paper, cloth, and / or other insulating materials. Additionally, the dielectric layer can have different thicknesses, such as on the order of 5 to 250 micrometers. Although the embodiments are not limited thereto, and the dielectric layer can be thicker or thinner to affect the stiffness and / or comfort of the wearable device for the user or to modulate the sensitivity of the sensor circuit 103.

[0053] For different users and / or based on the measured location, the shape of the pulse waveform may be different. For example, a wider pulse pressure may indicate or suggest aortic regurgitation (during cardiac diastole, the arterial pressure drops to fill the left ventricle by retrograde flow through the aortic valve into the artery). A narrow pulse pressure may indicate cardiac tamponade or any other kind of low-output state (e.g., severe cardiogenic shock, massive pulmonary embolism, or tension pneumothorax). Additionally, the shape of the pulse waveform can depend on the location of measurement (such as the further away from the aorta (e.g., brachial artery, radial artery, femoral artery, and dorsalis pedis artery) the measurement is taken). However, accompanying the change in the shape of the waveform, the mean arterial pressure (MAP) may not change and / or vary within a threshold amount. This is because the change in flow resistance from the aorta to the radial artery is small. Once the location moves to the arterioles, the MAP starts to change. The changes in the waveform from the aortic location to the dorsalis pedis artery can include: an increase in the systolic peak, an incisura further away from the systolic peak, a lower end-diastolic pressure (e.g., a wider pulse pressure), and a later pulse arrival (e.g., a sixty-second delay from the aorta to the radial artery). Sometimes the resulting shape is referred to as distal systolic pulse amplification because the systolic peak is steeper and further down the arterial tree.

[0054] Use a non-invasive device including a wearable device containing a sensor circuit to output a pulse waveform and determine various hemodynamic parameters according to embodiments of the present disclosure. The device can be used to monitor heart rate, diastolic blood pressure, systolic blood pressure, arterial stiffness, blood volume, and other parameters. Previous invasive devices (such as arterial catheters) were medically inserted into the user's body, which can be painful, limit patient movement, and may put the user at risk of infection and other complications. For example, an arterial catheter is a thin tube inserted into the user's artery. Typically, the catheter is inserted into the radial artery in the wrist, but it can 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 catheters can be used in critical care medicine and anesthesia to directly and real-time monitor blood pressure. Since the insertion can be painful, an anesthetic (e.g., lidocaine) can be used to make the insertion more tolerable and help prevent vasospasm. Complications caused by arterial catheters can lead to tissue damage and even amputation. The device according to the present disclosure can be used to non-invasively monitor blood pressure in real-time. The device can avoid and / or mitigate the risks caused by invasive devices, such as temporary occlusion of the artery, pseudoaneurysm, hematoma formation or bleeding at the puncture site, abscess, cellulitis, median nerve palsy, thromboarteritis, air embolism, compartment syndrome, and carpal tunnel syndrome, nerve injury, etc.

[0055] As Figure 1B shown, various characteristics can be modified to adjust the sensitivity of the device and / or improve the signal acquired by the electrodes. Figure 1BAn example device is shown that includes a plurality of electrodes 102-1, 102-2, and 102-3. Each of the electrodes 102-1, 102-2, 102-3 is used to sense pressure or capacitance changes caused by a pulse pressure event (e.g., caused by a change in the distance between the electrode and the skin surface), as previously described. The electrodes 102-1, 102-2, and 102-3 can be 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 can be placed at different locations on the device to improve position accuracy and / or provide one or more reference signals for differential analysis. In some embodiments, each of the electrodes 102-1, 102-2, 102-3 provides a signal to the electrical signal sensing circuit 106 indicative of a pressure or capacitance change (caused by a pulse pressure). In certain embodiments, the transducer circuit 110 can have a floating ground. In other specific embodiments, at least one of the sensor circuits has a floating ground (e.g., two sensor circuits, each having a floating ground; all sensor circuits, each having a floating ground, etc.). Additionally, at least one of the transducer 110 and the sensor circuits can have a floating ground.

[0056] Although Figure 1B (and including but not limited to Figure 2A , 2B and other illustrations in 2D) do not show the sensor circuits connected to the electrodes and / or the sensor circuits connected to each of the plurality of electrodes, one of ordinary skill in the art will understand that: according to various embodiments, each electrode is connected to a sensor circuit, as previously described. In this manner, Figure 1B the illustrations of

[0057] and other illustrations do not show the sensor circuits for clarity purposes and this is not intended to be limiting.

[0058] In some embodiments, one or more of the plurality of electrodes 102-1, 102-2, 102-3 may be electrically insulated from the user's skin. As described above, the electrodes 102-1, 102-2, 102-3 may be insulated by adding dielectric layers 108-1, 108-2, 108-3 to some or all of the plurality of electrodes 102-1, 102-2, 102-3. The dielectric layers 108-1, 108-2, 108-3 may surround the electrodes 102-1, 102-2, 102-3 and / or their respective sensor circuits. However, embodiments in accordance with the present disclosure are not limited thereto and may include a dielectric layer that is positioned at a portion and / or region of the electrode that is arranged to contact the skin surface, and / or surrounds at least a portion of the respective electrode or sensor circuit.

[0059] As Figure 1B shown, the transducer circuit 110 may be used to provide a differential mode to subtract artifacts. The artifacts may be baseline drifts attributed to the user's movement, such as limb movement, respiration, and / or changes in body temperature. In various embodiments, the different electrodes 102-1, 102-2, and 102-3 of the transducer circuit 110 have different structural attributes and / or characteristics that are used to modify the sensitivity level of the respective sensor circuit including the electrode. For example, the electrodes 102-1, 102-2, and 102-3 may be of different shapes (e.g., geometric dimensions), may be positioned at different locations relative to the user and / or the device, and may be formed of different materials. In other embodiments, the different structural attributes and / or characteristics may include: different compositions, structural components, textures, and / or thicknesses of the sealing material for electrically isolating the electrodes. For example, the dielectric layers of the respective electrodes 102-1, 102-2, 102-3 may be formed of dielectric materials having different compositions, structures, and / or thicknesses in order to modify the sensitivity level and / or shielding characteristics for isolating the electrodes. Thus, the plurality of electrodes may have a sealing material that is configured and arranged to set the sensitivity level of each of the plurality of electrodes.

[0060] In various embodiments, the device further includes a power supply circuit 112. The power supply circuit 112 provides power to at least the electrical signal sensing circuit 106. In some particular implementations, the power supply circuit 112 is a passively or inductively powered circuit, such as an inductor circuit. Example power supply circuits include batteries, solar converters, electromechanical systems, wall jacks (e.g., mains power), and other power sources.

[0061] Figure 2AAn example of a device is shown that includes a sensor circuit 103 having electrodes 214 that interact with the skin 218. As previously described, the sensor circuit and electrodes can sense capacitance changes through the proximity of the user's skin (as opposed to physically deforming as a capacitive sensor) and thereby act as or function as a proximity sensor. It has been found that a (proximity) sensor circuit with a single electrode 214 placed near an arterial pulse point (e.g., artery 216) can be used to measure an arterial pulse waveform via capacitance changes. Heart rate and other hemodynamic parameters can be extracted from this waveform. The electrode 214 can be in direct contact with the skin 218 or electrically insulated or isolated from the skin 218. It does not need to be mechanically coupled to the skin 218. The electrically insulating composition, structure, and thickness can be selected to modify the sensitivity of the sensor. A spacer structure can be used to determine capacitance changes between the electrode and the skin. The circuit can have a floating ground (e.g., the sensor circuit and / or transducer circuit can have a floating ground).

[0062] An array of electrodes can be used to improve position accuracy and / or provide a reference signal for differential analysis. Also, the signal can be improved by an electrode design that optimizes the fringe field distribution. For example, in some embodiments, an analog response is sensed by an array of sensor circuits, each having a single electrode. Two or more electrodes in the array can have different sensitivity levels and the analog responses sensed by two or more sensor circuits in the array can be used for differential sensing.

[0063] Figure 2B An example of a pulse waveform 209 sensed using the device as Figure 2A shown is presented. As shown, the periodicity of the pulse waveform 209 reflects the cardiac cycle and can be used to determine the user's heart rate.

[0064] Figure 2C An example mechanism of a device for monitoring pulse wave events is shown. As Figure 2C shown, the user's skin 218 acts as a ground plane for the mechanism. Without being bound by a particular theory, it is believed that the mechanisms behind one or more aspects of the embodiments discussed in this disclosure are as follows: (i) the skin 218 acts as a ground plane and arterial pressure changes cause displacement of the surface of the skin 218, and this changes the distance between the electrode 214 and the skin 218, which is measured as a change in capacitance; (ii) the electrical potential of the blood in the artery 216 (and the overlying skin) changes with each heartbeat, and this modifies the fringe field lines, which is reflected as a change in impedance; and (iii) involves a combination (contribution) from each of the above mechanisms.

[0065] Figure 2D An example is shown as Figure 2CAn example of the device shown further includes one or more spacers that set the distance (e.g., minimum distance) between at least a portion of the sensor circuit (e.g., electrode 214) and the skin 218. The spacer 217 includes one or more structures formed of a material in which the length (e.g., the distance from the electrode to the skin surface) sets the distance between at least a portion of the sensor circuit / electrode and the skin. The length can range from 0.1 millimeter (mm) to 1 mm, however embodiments are not limited thereto. Although Figure 2D the embodiments shown have one spacer with a rectangular shape, embodiments are not limited thereto and can include more than one spacer and spacers of different shapes (such as layers of textured and / or structured materials).

[0066] Figure 3 is a block diagram illustrating an example method of implementing an electronic device and / or signal flow according to the present disclosure, from a device located at or near the skin of a user (including, for example, sensor circuit 324, transducer circuit 326, electrical signal sensing circuit 327, and communication circuit 330) to a remote / wireless communication transceiver and CPU 334 (e.g., received via antenna 336). The CPU 334 and / or the electrical signal sensing circuit 327 can be programmed to perform the following operations disclosed herein, including but not limited to: processing raw data indicating the presence of a specific hemodynamic signal; establishing a waveform from the raw data; and / or calculating the integration, quality, and correlation of the hemodynamic signal and / or waveform for a specific application, the specific application being related to the hemodynamic state or health of the user (the user's heart rate or other hemodynamic metrics or parameters (such as diastolic blood pressure, systolic blood pressure, arterial stiffness, and blood volume), and / or indicating a change in one or more metrics or parameters).

[0067] The electrodes of the sensor circuit 324 capture capacitance changes in response to a pulse wave event and provide the capacitance changes to the transducer circuit 326. In some embodiments, the transducer circuit 324 is or includes a capacitance-to-digital converter. The capacitance-to-digital converter converts the capacitance value (e.g., relative change) to a digital signal and outputs the digital signal to the electrical signal sensing circuit 327, which can include or be a microcontroller or other processing circuitry. The electrical signal sensing circuit 327, using the power provided by the power supply 328, measures and / or records the arterial pulse waveform and optionally controls signals, calculates the quality of the data, and / or determines one or more hemodynamic parameters. The electrical signal sensing circuit 327 can output the waveform and other optional data to the CPU 334 via the communication circuit 330 (e.g., transceiver) and antenna 332.

[0068] The sensing devices described herein can monitor pulse wave events in a hands - free manner and without interference from ambient noise (e.g., human voices and other background noise, electrical interference, and ambient light). Additionally, the electrical signal sensing circuit can sense hemodynamic or pulse wave events in response to electrical signals from the transducer circuit. The electrode (or an array of electrodes) can consume a relatively low amount of power (e.g., between (less than) 5 microwatts and 3 milliwatts). In some specific embodiments, power consumption can be further reduced by saving data only after a trigger event and / or transmitting the saved data in a burst transmission. The trigger event can include specific cardiac events indicating problems (such as a heart rate above or below a threshold amount and / or specific waveform characteristics).

[0069] Figure 4A-5B Various example devices with a sensor array are shown in accordance with the present disclosure. For example, Figure 4A-4B An example device with four electrodes configured to interact with a user's skin is shown.

[0070] Figure 4A A top - down (or bird's - eye) view of a device including a sensor array is shown. The sensor array has four sensor circuits including four electrodes 447, 449, 451, 453. The line width and spacing can be on the order of 0.1 mm to 20 mm for pulse monitoring applications. As shown, the sensor array includes optional ground connections 440, 458 and optional active shield connections 442, 448, 450, 456. The array of sensors further includes sensor connections 444, 446, 452, 454 and insulating layers 460, 443.

[0071] Figure 4B is Figure 4A A side view of the device shown. As shown, the layer includes an insulating layer 460, four electrodes 445 (e.g., Figure 4A the electrodes 447, 449, 451, 453 shown) and other insulating layers 443. The device includes an effective portion (or area) 455 configured to be close to or in contact with the skin of a user or other object. The length of the effective portion 455 can be on the order of 0.1 mm to 20 mm for pulse monitoring applications. Additionally, the effective portion 455 can be in contact with or not in contact with the skin and be up to 1 mm from the skin. In various specific embodiments, the distance is typically less than 100 microns from the skin, which can be a distance sufficient to obtain a low enough resulting signal - to - noise value to obtain a heart rate and / or blood pressure therefrom. In specific embodiments, for sensitivity purposes and to reduce contact with the skin, the electrodes 445 can be textured or wrinkled. Smaller effective areas can have higher sensitivity, but may be difficult to precisely position.

[0072] In various embodiments, the device includes an array of encapsulated sensors, the array of sensors including (four) electrodes 445 configured to interact with a user's skin. The array of sensors (e.g., electrodes) can be encapsulated in an insulating material (e.g., a dielectric material) to provide environmental stability and moisture resistance. The insulating material can include polyester, polyolefin, fluoropolymer, polyimide, polyvinyl chloride, cellulose, paper, cloth, and other materials. The encapsulation thickness can be on the order of 5 to 250 microns or higher. Similarly, the optional adhesive and conductive layer thicknesses can be on the order of tens of microns and are typically less than 70 and 5 microns, respectively, for the adhesive and conductive layers. The (multiple) conductive layer(s) can optionally be a passive shielding layer and / or be connected to control electronics to provide active shielding.

[0073] In a particular embodiment, the layer includes: an insulating layer with optional shielding and adhesive coatings, an insulating layer, one or more electrodes, another insulating layer, and another insulating layer with optional shielding and adhesive coatings, as shown and discussed further herein. Figure 5A-5B As shown and discussed further herein.

[0074] In some embodiments, the array of sensors (e.g., electrodes) can be encapsulated in an insulating material (e.g., a dielectric material) to provide increased environmental stability and moisture resistance. One or more insulating layers can be slits in one or more locations to mechanically isolate the individual sensor circuits and increase the conformity of the encapsulated sensors to the underlying substrate.

[0075] In a further particular embodiment, the array of encapsulated sensors includes (four) electrodes 445 and a spacer layer. The spacer layer includes one or more spacers that can set or control the distance of the sensor circuit and / or the electrode (or at least a portion of the electrode) from the skin surface, as shown previously. Figure 2D The spacer layer can minimize or mitigate parasitic capacitance from non-active (non-sensor) regions. The spacer layer thickness can be on the order of 0.1 mm to 5 mm or higher as long as the distance does not affect the sensitivity of the sensor. The array of sensors (e.g., electrodes) can be encapsulated in an insulating material (e.g., a dielectric material) to provide environmental stability and moisture resistance. The encapsulation thickness can be on the order of 5 to 250 microns or higher. Similarly, the optional adhesive and conductive layer thicknesses can be on the order of tens of microns and are typically less than 70 and 5 microns, respectively, for the adhesive and conductive layers.

[0076] An array of encapsulated sensors may further include a shielding layer. As further described below, one or more insulating layers may have an adhesive coating on their inner surfaces to cause the layer to adhere to other layers, such as adhering an insulating layer to another insulating layer(s). The insulating layer may have a conductive layer on its outer surface that contacts the user's skin. The conductive layer may alternatively be sandwiched between two insulating layers. The conductive material may include, for example, aluminum, gold, carbon, or copper that has been printed, evaporated, sputtered, or electroplated on a non-conductive substrate (e.g., a PET or polyimide substrate). The insulating layer may be slits in one or more locations to mechanically isolate the individual sensor circuits and increase the conformity of the encapsulated sensor circuits to the underlying substrate. Thus, the substrate may be configured and arranged as a user accessory that mates with the user's wrist, limb, or other body part.

[0077] In a particular experimental embodiment, the insulating layers 443, 460 and the electrodes 445 are formed from a flexible flat cable (FFC / FPC) (such as the commercially available Molex 15168-0147), the insulating layer 460 with an adhesive coating is formed from polyethylene terephthalate (PET) with an adhesive (such as the commercially available Avery 156660), the insulating layer 443 with a conductive material is formed from 12 micron PET with evaporated aluminum (such as the commercially available Celplast Cel-Met 48g) having an optical density of about or greater than 2, and the spacer layer is formed from a foam tape layer (such as the commercially available Nexcare 731). Each electrode may be 0.625 mm wide with a 0.625 mm spacing between each electrode.

[0078] The different electrodes 445 may have different capacitance sensitivities. The device may include a spacer layer that covers some but not all of the active portions of the sensor circuits. The sensor circuits may have isolated electronics for readout to prevent or mitigate crosstalk through a common circuit.

[0079] As described throughout this disclosure (e.g., including Figure 1A-1B, 2A, 2C - 2D, 4A - 4B, 5A - 5B, 6B, and 16) can be such that the flexible or bending angle of the sensor circuit is sufficient to capture changes in pressure or capacitance (e.g., changes in capacitance value). More specifically, the stiffness of the sensor circuit is inversely proportional to the thickness and / or length of the sensor circuit (e.g., the thicker or longer the electrode, the more rigid). The flexibility and the thickness (and / or length) can be configured relative to each other to be sufficient to provide sensitivity to pressure changes from 0.3 kilopascals (kPa) to 1 kPa and / or capacitance changes in the range of plus or minus 15 picofarads (pF) compared to the baseline capacitance of the sensor circuit. In a more specific embodiment, the flexibility and the thickness and / or length can be configured relative to each other to be sufficient to provide sensitivity to pressure changes from 0.5 kPa to 1 kPa. Additionally, as described herein, when the sensor contacts the skin or other surface, measurements of pressure changes (which indicate changes in capacitance) can be sensed. When the (multiple) electrodes are not in contact with the user's skin or other surface (but are within 1 mm), changes in the sensed capacitance can be acquired.

[0080] Figure 5A-5B An example device is shown having an array of encapsulated sensors, the array of sensors including a plurality (e.g., four) of electrodes having 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., non - electrodes 549 and 550). Alternatively and / or additionally, some of the sensor circuits (e.g., electrodes 549 and 550) and portions of the insulating layers 541, 543 are shorter (relative to the end of the device proximate the active portion 551) than the remaining sensors (e.g., electrodes 547, 548). The sensor circuits can have isolated electronics for readout to prevent or mitigate crosstalk through a common circuit. As previously described, one or more insulating layers 530 can have an adhesive coating on their inner surfaces such that the insulating layer 530 adheres to other layers, such as adhering the insulating layer 530 to other insulating layers 541, 544. Other insulating layers 544 can have a conductive layer on their outer surfaces that contacts the user's skin.

[0081] Figure 5AA top-down (or bird's-eye) view of a device including a sensor array having four electrodes 547, 548, 549, 550 is shown. As shown, the sensor array includes optional ground connections 531, 540 and optional active shield connections 532, 535, 536, 539. The array of sensors further includes: sensor connections 533, 534, 537, 538; insulating layers 541, 543; a spacer layer 545; and additional insulating layers 544, 530 having optional shielding and adhesive coatings. The insulating layers 541, 543 can be slits at one or more locations 542 to mechanically isolate the individual sensor circuits and increase the conformity of the packaged sensors to the underlying substrate.

[0082] Figure 5B is Figure 5A A side view of the device shown. As shown, the layers include: an insulating layer 530 having an adhesive coating on its inner surface (e.g., on the surface proximate to insulating layer 541), insulating layer 541, four electrodes 546 (e.g., Figure 5A the electrodes 547, 548, 549, 550 shown), another insulating layer 543, a spacer layer 545, and another insulating layer 544 having a conductive material on its outer surface (e.g., on the surface opposite and / or proximate to spacer layer 545). The device includes an active area 551, as previously described.

[0083] Figure 6A-6C A device according to the present disclosure is shown. As Figure 6B and 6C shown, in certain embodiments, the device can have a flexible strip sensor array 602 configured and arranged to sense a pulse waveform. A wristband 604 can be used to hold the flexible strip sensor array 602 in place, as Figure 6C shown, which can be placed around the wrist of a user 603. Figure 6A The figure shown depicts capacitance data 601 for a typical radial artery pulse waveform shape. In an exemplary experimental embodiment, a bandpass filter (20 Hz / 0.5 Hz) is used to process the data, which results in a calculated heart rate of 71 bpm. (From Fitbit Charge HR TM of) The reference heart rate is 70 bpm, which illustrates that the sensor signal reflects the cardiac cycle. For this embodiment, the flexible strip sensor array 602 is held by an elastic wristband 604 to contact a plane close to the skin of the user. In various embodiments, a Molex 15168-0147 FFC jumper cable can be used as the flexible strip sensor array. The heart rate can be calculated from the Fourier transform of such waveform data. The flexible strip sensor array 602 can be connected to a Bluetooth proximity sensing circuit (e.g., an electrical signal sensing circuit)

[0084] Figure 7 illustrates example data captured using a device (such as the device shown Figure 6B-6C ) according to various embodiments. In some embodiments, the device may include a ribbon cable that is implemented such that multiple channels can be measured simultaneously (or alternatively, concurrently or sequentially) along different signal paths provided by the conductive wires of the cable. In such embodiments, different electrodes (and corresponding sensor circuits) are configured as one of the multiple channels (e.g., signal paths), which respectively carry signals for sequential processing by the electrical signal sensing circuit and / or for concurrent processing or simultaneous processing by the electrical signal sensing circuit. As Figure 7 shown, as an example implementation of four channels that can be measured, the device may include four electrodes, each of the four electrodes being disposed in a respective signal path / channel. Similar to Figure 6A , a bandpass filter (20 Hz / 0.5 Hz) is used to extract data (e.g., from unfiltered 705, 707, 709, 711 from the four channels). In this experimental embodiment, the calculated heart rate is 71 bpm, and the reference heart rate (Fitbit Charge HR TM ) is 70 bpm. For this embodiment, the flexible ribbon sensor array is held by an elastic wristband in contact with a plane adjacent to the user's skin. In various embodiments, a Molex 15168-0147 FFC jumper cable can be used as the flexible ribbon sensor array. The heart rate can be calculated from the Fourier transform of such waveform data. The flexible ribbon electrodes can be connected to a Bluetooth proximity sensing circuit (e.g., an electrical signal sensing circuit)

[0085] Figure 8 illustrates examples of data 802, 804, 806, 808 captured using the device. In some embodiments, the device may have an additional dielectric insulation layer (tape) for modifying the response signal-to-noise ratio. The top two illustrations show the response of electrodes without a dielectric insulation layer (e.g., data 802, 804). The bottom two illustrations show the response of electrodes with one dielectric insulation layer and demonstrate a reduction in signal amplitude (e.g., data 806, 808).

[0086] Figure 9A-9B illustrates an example device having multiple channels and data captured using the device in various embodiments. One or more of the channels may have (a) dielectric layer(s) or be associated with (a) dielectric layer(s), which may reduce the signal strength. Figure 9AIllustrates example data captured using a device having four channels (e.g., signal paths in which electrodes are configured and which respectively carry signals). Compared to bare contacts, one or two dielectric layers (e.g., one or two pieces of tape) can be utilized to reduce the amplitude of the signal. As shown, waveform 914 represents data captured using electrodes without a dielectric layer, waveform 915 represents data captured using electrodes with one dielectric layer, waveform 916 represents data captured using electrodes with two dielectric layers, and waveform 917 represents data captured using electrodes without a dielectric layer. An example device for collecting the shown data can include a sensor strip that is mechanically coupled to a user's skin (such as via a wristband).

[0087] In some embodiments, the dielectric layer can modulate the amplitude of the pulse waveform, but may not impede the observation of baseline drift due to motion or respiratory artifacts. Figure 9B Illustrates data captured using the above-described device in response to a signal change that is caused by a user moving their hand up and down with an amplitude of 6 inches. As shown, each channel is used to capture the observation of baseline drift due to user motion, which is respectively shown by waveforms 918, 919, 920, 921. A sensor circuit with a lower sensitivity to the pulse waveform signal (e.g., a sensor circuit with one or two layers of dielectric material) can act as a reference for removing baseline drift due to user motion in the differential mode.

[0088] Figure 10 Illustrates example data captured using a device according to various embodiments. Some embodiments can implement one or more electrodes (e.g., sensors) at various locations (such as the front, back, and / or sides of the wrist). The positions of the electrodes at different locations can act as a reference for the total motion artifact in the differential mode. Positions can be selected to mimic the motion artifacts observed at the pulse points. Figure 10 Illustrates different data captured using each electrode (e.g., configured in a channel) of a device that has four sensor circuits placed at different positions around the wrist. The captured data is represented as waveforms 1003, 1005, 1007, 1009. The sensor circuits can be mechanically coupled to the user via a wristband.

[0089] In some embodiments, different electrode types can be used to implement the device. For example, Figure 11-15B Illustrates data captured using different types of electrodes.

[0090] Figure 11 Illustrates example data captured using a device having a single strip electrode with a planar contact. Figure 11The data 1129 shown is unfiltered. A band-pass filter (20 Hz / 0.5 Hz) is used to extract the data. In an example experimental embodiment, the calculated heart rate is 63 bpm, and the reference heart rate (Fitbit Charge HR TM ) is 63 bpm. For this embodiment, the copper tape electrode is 6 mm wide and 3 centimeters (cm) long, has a planar copper contact with the user's skin, and is held by an elastic wristband to contact the plane adjacent to the user's skin, however the embodiment is not limited thereto. The (one or more) electrodes can be of various sizes, such as in the range of 0.5 mm to 6 mm wide, in the range of 0.5 mm to 1 cm wide, and in the range of 0.5 mm to 3 cm long.

[0091] Figure 12 Example data captured using the device according to various embodiments is shown. As previously described, the device includes at least one sensor circuit having an electrode, where the edge of the electrode is placed near the user's skin. The edge contact can be near the skin, but may not contact the user's skin. The closer the edge contact is to the skin, the stronger the signal obtained. Figure 12 An example pulse waveform 1238 captured using the above device is shown. The pulse waveform 1238 shows the signal from the sensor circuit, and the data 1234, 1236, and 1239 show the signals from the empty channel in the case where no sensor is connected. In this example, the sensor circuit includes a 6 mm wide copper tape electrode having an edge contact.

[0092] Figure 13A-13B Example data captured using the device according to various embodiments is shown. The device includes a single electrode formed of conductive cloth. For example, the cloth electrode can be 2 mm wide and 2 cm long. Figure 13A An example pulse waveform 1350 captured using the cloth electrode is shown. The electrode can be placed flat on the user's skin and can be fixed to the skin by a wristband. The user's arm may bend as the hand is raised, and data is captured after the user has been running in place. Figure 13B An example graph 1354 of the heart rate varying over time is shown and this example graph 1354 is generated in accordance with Figure 13A the data shown. A band-pass filter (20 Hz / 0.5 Hz) is used to process the pulse waveform data, the heart rate is calculated from the Fourier transform of the pulse waveform, and the heart rate values can be averaged over a period of time (e.g., 15 seconds). In this example, the reference data 1353 lags the experimental data by a period of time (e.g., 30 seconds) due to the difference in the averaging period.

[0093] Figure 14Shows example data captured using a device according to various embodiments. The device includes a single (woven) wire electrode. As shown, the captured data includes a pulse waveform 1457. To determine the heart rate, a bandpass filter (1 Hz / 2 Hz) is used to extract the data. In an example experimental embodiment, the calculated heart rate is 71 bpm, and the reference heart rate (Fitbit Charge HR TM ) is 72 bpm. The electrode can be formed of steel (e.g., steel picture wire) and held in place by an elastic wristband.

[0094] Figure 15A-15B Shows an example device according to various embodiments and data captured using the device. As Figure 15A shown, the electrode 1559 can include more complex geometries, such as a star-shaped copper foil electrode that lies flat on the user's skin and is held in place on the skin by a wristband. Figure 15B Shows example filtered and unfiltered pulse waveforms captured using the device shown in Figure 15A . A bandpass filter (20 Hz / 0.5 Hz) is used to extract the data. In an example experimental embodiment, the calculated heart rate is 71 bpm, and the reference heart rate (Fitbit Charge HR TM ) is 71 bpm.

[0095] Referring to the block diagram shown in Figure 3 , a signal stream from a wearable transducer is processed by a signal converter for digital processing (at a microcontroller) for wireless (and / or limited) communication to a remote user interface. In certain embodiments, signals picked up by a sensor circuit and processed and detected / measured by a transducer (e.g., a capacitance-digital converter) and an electrical signal sensing circuit (e.g., a microcontroller), regardless of whether the transducer and / or sensor circuit is initially configured to contact the user's skin (as in the case of a conductance transducer that only relies on conductance) and / or what type of interface exists between the user's skin and the transducer. Depending on the possible mechanisms noted above, in contrast to traditional sensor methods, such embodiments do not rely on the amount of initial contact with the user's skin and / or the type of interface (such traditional sensor methods are insensitive to changes in fringe fields and / or changes in the distance between the electrode and the skin). In various embodiments, such as in the case of a photoplethysmogram (PPG) sensor, the signal carried by the electrode is not affected or altered by changes in luminance caused by hemodynamic or pulse wave events.

[0096] Sensor circuits including a single electrode in various embodiments are used to perform proximity sensing. As previously described, changes in capacitance are borne by the electrode and the corresponding sensor circuit and in response to pressure and / or electric field modulation caused by hemodynamic or pulse wave events. The capacitance change may be attributed to changes in the pressure, geometry, or electric field distribution of blood vessels, but these parameters are not directly measured. The sensor circuit and the electrode capture (or sense) the capacitance change through proximity sensing of the user's skin (as opposed to physically deforming the device as a capacitance sensor), and thus function as or become a proximity sensor. The proximity sensing and / or capacitance change responds to modulating the distance between the user's skin and the sensor circuit and / or modulating the fringe field lines.

[0097] The various embodiments described above and the more detailed / experimental embodiments described further below refer to a user and a corresponding wearable device that mates with the user's skin or body. One of ordinary skill in the art can understand that the user is not limited to humans. According to certain embodiments, the user may include organisms or animals (other than humans), such as horses, dogs, cows, birds, reptiles, various animals monitored in a zoo or other types of organisms or animals (e.g., zebras, elephants, pandas, etc.), organisms or animals monitored in the wild, and other organisms. The skin of the user (e.g., an animal) may be covered with hair, and the wearable device described above may mate with the user's body or be mechanically constrained to the user's body.

[0098] Slides 17 and 18 in the provisional application (serial number 62 / 314,474) entitled "Proximity Sensors and Related Sensing Methods" filed on March 29, 2019 show detailed diagrams for certain specific embodiments, which show examples of how to implement such a sensor circuit, and are incorporated herein in their entirety for their teaching.

[0099] More specific / experimental embodiments

[0100] Embodiments in accordance with the present disclosure include the use of a device (the device includes an electrical signal sensing circuit and at least one sensor circuit having an electrode) to monitor capacitance changes and / or relative capacitance changes, the capacitance changes and / or relative capacitance changes in response to changes in the distance between the corresponding electrode and the user's skin and / or changes in the electric field near the arterial pulse point caused by a pulse wave event. Using the change in capacitance, a pulse waveform and / or a pressure difference can be determined. The pulse waveform can be used to non-invasively monitor hemodynamic parameters and / or changes in parameters including heart rate, diastolic blood pressure, systolic blood pressure, arterial stiffness, and blood volume.

[0101] Figure 16 Illustrates example data collected using a device according to various embodiments. The data includes a series of pulse waveforms 1664, 1665, 1666, 1667, 1668, 1669, 1670, 1671, 1672, 1673, 1674, 1675, 1676, and 1677 (hereinafter mainly referred to as "pulse waveforms" for convenience of reference) of various different shapes that can be captured using a device according to embodiments of the present disclosure. The illustrated pulse waveforms are obtained by measuring the relative change in capacitance and not based on the absolute value of the capacitance. However, embodiments according to the present disclosure are not limited thereto.

[0102] Figure 17A-17C Illustrates data collected using a device and data collected using an arterial line according to various pilot embodiments. The data obtained using the device (the device is placed close to the left radial artery pulse point of the user) tracks and / or mimics the data obtained using an arterial line implanted in the right radial artery. Figure 17A Illustrates that data 1773 obtained by a device according to various embodiments mimics data 1772 obtained by an arterial line. Figure 17B Illustrates data 1773 (e.g., waveform) and Figure 17C Illustrates data 1772 for further illustration, respectively.

[0103] Figure 18A-18C Illustrates example pulse waveform data collected using a device and collected using an arterial line according to various pilot embodiments. The device (the device is placed close to the left radial artery pulse point of the user) tracks and / or mimics the data obtained using an arterial line implanted in the right radial artery or the data obtained thereby. The heart rate can be determined by analyzing each heartbeat by measuring the length of the pulse wave. The heart rate variability can be determined from the distribution of the respective heart rate values. Figure 18A Illustrates that the pulse waveform data 1877 obtained by the device can mimic the pulse waveform data 1875 obtained by the arterial line. Figure 18B Illustrates the pulse waveform data 1877 (e.g., waveform) and Figure 18C Illustrates the pulse waveform data 1875 for further illustration, respectively.

[0104] Figure 19A-19CShows examples of changes in heart rate and blood pressure collected using a device and collected using an arterial line according to various experimental embodiments. In various embodiments, patterns and anomalies in heart rate and blood pressure can be tracked and / or monitored. Such patterns and / or anomalies can indicate various health conditions such as atrial fibrillation hypertension, peripheral vascular disease, aortic regurgitation, aortic stenosis, and / or left ventricular obstruction, and other conditions. Data obtained using a device (the device placed close to the user's left radial artery pulse point) can track and / or mimic data obtained using an arterial line implanted in the right radial artery. Figure 19A Shows that: data 1981 obtained by a device according to various embodiments mimics data 1979 obtained by an arterial line. Figure 19B Shows 1981 (e.g., waveform) and Figure 19C Shows data 1979, respectively, for further illustration.

[0105] Figure 20 Shows an example respiratory rate collected using a device according to various experimental embodiments. The device can be used to measure and / or monitor the respiratory rate from the respiratory pattern. For example, Figure 20 Shows data 2087, 2088, 2089, 2090 captured using four different signals and shows a baseline drift with a characteristic frequency periodicity related to the user's respiratory movement.

[0106] Figure 21 Shows example data collected using a device having multiple electrodes located at different positions according to various experimental embodiments. As previously described, the electrodes can be arranged to have multiple channels each carrying a signal that is processed by an electrical signal sensing device. Due to the respective positions of each electrode, the quality and amplitude of the data captured between channels (which can be captured simultaneously) may vary. Figure 21 Shows filtered data 2115, 2116, 2117, 2118 (e.g., filtered raw data captured using four channels).

[0107] Figure 22 Shows example data collected using a device having multiple electrodes located at different positions according to various experimental embodiments. As previously referenced Figure 21 In the above discussion, the position of the electrodes can affect the quality of the data captured. Additionally and / or alternatively, the position of the electrodes can result in a mixture of normal and inverted (respectively). Figure 22 Shows filtered data 2221, 2222, 2223, 2224 captured using four channels, as previously described.

[0108] Figure 23Illustrates example respiration rates collected using a device with multiple electrodes according to various pilot embodiments. In various embodiments, a band - pass filter can be used to process data captured using the (multiple) electrodes to reduce baseline drift and signal noise. For example, Figure 23 Illustrates filtered data 2345, 2346, 2347, 2348 captured using the same four signals (e.g., filtered using a band - pass filter from 0.1 Hz to 20 Hz).

[0109] As shown and previously described, the pulse waveform can be used to determine various hemodynamic parameters. For example, the shape and other characteristics of the pulse waveform can be correlated with blood pressure. In other embodiments, the heart rate and the rate of psychological change can be obtained by determining the timing of the heart rate and cardiac variability for each pulse. Further, changes in blood pressure can be monitored by first calibrating the data (such as calibrating the arterial line using inflatable cuff data).

[0110] A variety of different techniques, including feature analysis and computational fluid dynamics techniques, can be used to analyze pulse waveforms and / or determine various hemodynamic parameters. For example, features attributable to hemodynamic phenomena can be correlated with blood pressure, arterial stiffness, and other hemodynamic parameters. For more general and specific information regarding features attributable to hemodynamic phenomena, reference is made to Cecelia, Marina, and Phil Chowienczyk's "Role of Arterial Stiffness in Cardiovascular Disease" (JRSM Cardiovascular Disease 1.4 (2012): cvd.2012.012016, PMC, Web. January 31, 2017); David A. Donley et al.'s "Aerobic exercise training reduces arterial stiffness in metabolic syndrome" (published in the "Journal of Applied Physiology" on June 1, 2014, Vol. 116, No. 11, pp. 1396-1404); Baruch, Martin C. et al.'s "Validation of the pulse decomposition analysis algorithm using central arterial blood pressure" (Biomedical engineering online 13.1 (2014) 96.); and Munir, Shahzad et al.'s "Peripheral augmentation index defines the relationship between central and peripheral pulse pressure" (Hypertension 51.1 (2008): 112-118.), each of these documents being incorporated herein by reference in its 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 for arterial stiffness and can be correlated with peripheral and central blood pressure peaks (pPP and cPP).AI is a normalized parameter and can be analyzed without absolute calibration. Computational fluid dynamics techniques can include: modeling blood vessels as a network of inductance-capacitance-resistance (LCR) circuits and / or elastic tubes to calculate parameters such as pulse wave velocity and / or waveform shape. For more general and specific information related to computational fluid dynamics for determining hemodynamic parameters, reference is made to Lee, Byoung-Kwon's "Computational fluid dynamics in cardiovascular disease" (Korean Circulation Journal 41.8 (2011): 423-430.), and Xiaoman Xing and Mingshan Sun's "Optical blood pressure estimation with photoplethysmography and FFT-based neural networks" (Biomed. Opt. Express, 7, 0307-3020 (2016)), each of which is incorporated herein by reference in its entirety. Models that can be used to obtain the relationship between the pulse waveform (acquired by PPG) and blood pressure (where g is defined by the modulus E of the blood vessel wall) include:.

[0111] E = E0e γP 。

[0112] For example, the normalized waveform can be given by the following equation:

[0113]

[0114]

[0115]

[0116] Various techniques can be used to correlate a pulse waveform with a blood pressure value. For more general and specific information related to correlating a pulse waveform with a blood pressure value, reference is made to Xiaoman Xing and Mingshan Sun's "Optical blood pressure estimation with photoplethysmography and FFT-based neural networks" (Biomedical engineering online 7.8 (2016): 3007-3020), and

[0117] http: / / cs229.stanford.edu / proj2014 / Sharath%20Ananth,Blood%20Pressure%20Detection%20from%20PPG.pdf, each of which is incorporated herein by reference in its entirety.

[0118] Figure 24A-24B An example pulse waveform generated using a wearable device, an arterial line, and an optical sensor is shown in accordance with various embodiments. The wearable device includes a sensor circuit having electrodes, as described previously.

[0119] As Figure 24A shown, particularly when the secondary feature is large and separated from the primary peak, the pulse waveform 2455 generated using the wearable device captures the secondary feature. Additionally, the pulse waveform 2455 is similar to the pulse waveform 2457 generated using the arterial line and the pulse waveform 2459 generated using an optical sensor (e.g., photoplethysmogram (PPG)).

[0120] Figure 24B The ability of an electrical signal sensing device to capture the fine features of the pulse waveform 2460, which can correlate the waveform with blood pressure, is shown. A PPG sensor can be used to wash out such features (highlighted by the circles surrounding portions of the pulse waveforms 2460, 2462, 2464), as shown by the pulse waveform 2464 captured using PPG.

[0121] Terms used to illustrate orientation and direction, such as high / low, left / right, top / bottom, up / down, above / below, vertical, horizontal may be used herein to refer to the relative positions of components as shown in the accompanying drawings. Similarly, heating or cooling are relative terms of a technique, and considering that the direction of temperature change can be altered according to the desired temperature change, it can be understood that a heat source and a cold source can be synonymous. It should be understood that these terms are only for convenience of labeling, and in actual use, the disclosed structure may be oriented differently from the orientation shown in the accompanying drawings. Therefore, these terms should not be construed in a limiting manner.

[0122] It may also be helpful to understand the context / sense of the following terms: The term "electrode" refers to or includes a conductive conductor; the term "sensor circuit" refers to or includes a circuit containing electrodes and a connection to a transducer circuit (e.g., having a sensor connector for inserting or otherwise connecting the electrodes to the transducer circuit), and the circuit detects or measures a capacitance value and / or a change in capacitance via the electrodes and is used to output the same capacitance value and / or change in capacitance to the transducer circuit; the sensor circuit may additionally include various other components, such as those shown in Figure 4A-4B as well as 5A - 5B. For example, the sensor circuit may include a multi-layer structure containing electrodes and various dielectric and conductive layers; the term "transducer circuit" refers to or includes a circuit system that converts a change in physical mass (such as a change in capacitance provided by the sensor circuit) into an electrical signal; for example, the transducer circuit may include a capacitance-to-digital converter; the term "pulse wave event" refers to or includes a hemodynamic response and / or property (such as a change in heart rate or heart sound, blood pressure or blood flow velocity, etc.) caused by and / or indicating a heartbeat (e.g., contraction of the heart muscle); the term "pulse waveform" refers to or includes a signal or wave generated by a pulse wave event, for example, the pulse waveform includes an arterial pulse waveform; for example, a waveform caused by the heart when the heart contracts and the wave travels along the arterial wall of the arterial tree; the term "electrical signal sensing circuit" refers to or includes a circuit for sensing a hemodynamic or pulse wave event using an electrical signal from the transducer circuit; example electrical signal sensing circuits include a microcontroller or other processing circuit and example transducer circuits include a capacitance-to-digital converter, however, the embodiments are not limited thereto; the term "communication circuit" refers to or includes a circuit that outputs data to other external circuits, and the circuit may include wireless or wired communication; example communication circuits include a transceiver, however, the embodiments are not limited thereto; the term "hemodynamics" or "hemodynamic parameter" refers to or includes parameters related to the flow of blood within organs, blood vessels, and body tissues; example hemodynamics or hemodynamic parameters may include diastolic blood pressure, systolic blood pressure, arterial stiffness, and blood volume as well as other parameters.

[0123] Various embodiments are implemented in accordance with the priority of, and are hereby incorporated by reference in their entirety from, the provisional application (serial number 62 / 314,474) filed on Mar. 29, 2016, entitled "Proximity Sensors and Related Sensing Methods". For example, the embodiments in this document and / or in the provisional application (including the slides therein) may be combined in various degrees (including in whole). Reference may also be made to the experimental teachings and the basic references provided in the provisional application, including the slides that form part of the provisional application. Unless otherwise specified, the embodiments discussed in the slides are not intended to be limited in any way to any part of the overall technical disclosure or the claimed invention.

[0124] Various blocks, modules, or other circuits may be implemented to perform one or more of the operations or activities described herein and / or shown in the figures. For example, processes such as heating, etching, and deposition may be automated by using various circuits and associated machines. In such a context, various depicted functions may be implemented by using circuits that perform one or more of these operations / activities or related operations / activities. In various embodiments, for such embodiments where limited flexibility is sufficient, hardwired control blocks may be used to minimize area. Alternatively and / or additionally, in certain of the above-discussed embodiments, one or more modules are discrete logic circuits or programmable logic circuits that are configured and arranged to perform these operations / activities.

[0125] As an example, the specification describes and / or illustrates facilitating the implementation of the claimed disclosure with various circuits or circuitry, which may be presented as or use terms (such as depictions of blocks, modules, devices, systems, and / or other circuit types). Such circuits or circuitry may be used with other components (wristbands, external processing circuitry, etc.) to illustrate how certain embodiments may be implemented in terms of form or structure, steps, functions, operations, activities, etc. For example, in some of the embodiments discussed above, one or more of the terms shown in this context represent circuitry (e.g., discrete logic circuitry or (semi)-programmable circuitry) configured and arranged to implement these operations / activities, as may be implemented in the methods shown in a slide. In some embodiments, such terms shown represent one or more computer circuitry (e.g., a microcomputer or other CPU), which may be understood to include memory circuitry that stores code (for executing a program as an instruction set / multiple instruction sets) for: performing basic algorithms (e.g., detecting pressure differences and / or capacitance changes caused by pulse wave events), and / or involving the determination of hemodynamic parameters, and / or more complex processing / algorithms that would be understood from known literature describing such specific parameter sensing. Such processing / algorithms will be specifically implemented to perform relevant steps, functions, operations, activities appropriate to a particular application. The specification may also refer to adjectives that do not denote any property of a structure ("first [type of structure]" and "second [type of structure]"), in which case the adjective is only used for an English antecedent to distinguish one such similarly named structure from another (e.g., "first electrode..." may be interpreted as "electrode...").

[0126] Based on the above discussion and illustration, those skilled in the art will readily appreciate that various modifications and variations can be made to the various embodiments without strictly following the exemplary embodiments shown and described herein. For example, while retaining one or more aspects of the embodiments herein, the methods illustrated in the figures may involve steps being implemented in various orders, or may involve fewer or more steps. Such modifications do not depart from the true spirit and scope of the various aspects of the present disclosure, including those set forth in the claims.

Claims

1. A wearable device, comprising: A transducer circuit having an array of sensor circuits, each sensor circuit in the array of sensor circuits including a single electrode configured to sense a change in capacitance together with the sensor circuit, and the transducer circuit for converting the change in capacitance into an electrical signal, the change in capacitance being responsive to surface displacement, pressure, and / or electric field modulation caused by a hemodynamic or pulse wave event associated with a pulse waveform having a main peak; An electrical signal sensing and processing circuit for sensing the hemodynamic or pulse wave event in response to the electrical signal from the transducer circuit and providing an indication of a blood pressure value based on characteristics of an arterial pulse waveform corresponding to the electrical signal from the transducer circuit; A substrate for supporting and at least partially enclosing the transducer circuit and the electrical signal sensing and processing circuit and mating with a portion of the user including a blood vessel for hemodynamic monitoring, and wherein the single electrode is positioned to contact or be close enough to the portion of the user to capture secondary features of the pulse waveform, and / or to respond to small changes in the proximity from the single electrode to the portion of the user including the blood vessel, and thereby electrically sense the hemodynamic or pulse wave event via the electrical signal, the proximity being in the range of zero to one millimeter (mm), the secondary features being separated from the main peak and enabling the pulse waveform to be related to blood pressure, wherein the sensor circuits of the array are for capturing the capacitance change via proximity sensing through the portion of the user in response to modulated fringe field lines, and wherein the electrical signal sensing and processing circuit is for monitoring at least one of the following: a pressure difference on the order of 1 kilopascal (kPa) indicating a change in capacitance and detectable by the single electrode whether or not the single electrode contacts the portion, and a relative capacitance change on the order of 15 picofarads (pF) compared to the basic capacitance of the sensor circuit; And A communication circuit for responding to the electrical signal sensing and processing circuit by communicating or transmitting data indicative of the hemodynamic monitoring.

2. The wearable device according to claim 1, wherein The electrical signal sensing and processing circuit is further for providing a differential mode by subtracting artifacts responsive to a plurality of electrodes in the array of sensor circuits, wherein the artifacts are due to factors including one or more of: pressure changes or motion attributable to breathing, arm movement, and external vibration.

3. The wearable device according to claim 1, characterized in that, The electrical signal sensing and processing circuit is further for monitoring a pressure difference of less than 1 kilopascal (kPa) indicating a change in capacitance and detectable by the single electrode whether or not the single electrode contacts the portion of the user or the skin.

4. The wearable device according to claim 1, wherein The electrical signal sensing and processing circuit is further for monitoring a relative capacitance change in the range of plus or minus 15 picofarads (pF) compared to the basic capacitance of the sensor circuit.

5. The wearable device according to claim 1, characterized in that, The electrical signal sensing and processing circuit is further configured to monitor: a pressure difference less than 1 kilopascal (kPa), the pressure difference indicating a change in capacitance and being detectable by the single electrode, whether or not the single electrode is in contact with the portion or skin of the user; and a relative capacitance change within a range of plus or minus 15 picofarads (pF) compared to the baseline capacitance of the sensor circuit.

6. The wearable device according to claim 1, wherein The electrical signal sensing and processing circuit is independent of the amount of initial contact with the portion or skin of the user.

7. The wearable device according to claim 1, wherein The transducer circuit operates using a floating ground, and wherein the data further indicates a change in at least one of: diastolic blood pressure, systolic blood pressure, and arterial stiffness.

8. The wearable device according to claim 1, wherein Each of the plurality of electrodes in the array of sensor circuits is associated with a different characteristic based on at least one of the electrode geometry and the dielectric layer used with the electrode.

9. The wearable device according to claim 1, wherein The plurality of electrodes in the array of sensor circuits have a sealing material that collectively sets the sensitivity level of the plurality of electrodes.

10. The wearable device according to claim 1, wherein, The communication circuit is further configured to transmit the captured capacitance changes caused by the hemodynamic or pulse wave event to an external processing circuitry system.

11. The wearable device according to claim 1, further comprising a passively or inductively powered circuit configured to supply power to at least the electrical signal sensing and processing circuit.

12. The wearable device according to claim 1, wherein The portion of the user includes the skin of the user, wherein the substrate is part of a user accessory that mates with the wrist or other body part of the user, and wherein the single electrode contacts or is sufficiently close to the portion or skin of the user to capture secondary features of the pulse waveform.

13. The wearable device according to claim 1, wherein The electrical signal sensing and processing circuit is further configured and arranged to use the hemodynamic or pulse wave event to determine hemodynamic parameters of the user or the heart of the user.

14. A method for hemodynamic monitoring via a wearable device, the method comprising: using a flexible or bendable substrate to: (a) support an electrical signal sensing and processing circuit and a transducer circuit having an array of sensor circuits, and (b) mate with a portion of the user that includes blood vessels, wherein the substrate is configured to position the transducer circuit sufficiently close to the portion of the user to electrically sense, via a change in capacitance carried by the respective electrodes of each sensor circuit of the array, a hemodynamic or pulse wave event associated with a pulse waveform having a major peak, wherein each sensor circuit includes a single electrode and the change in capacitance indicates a pressure and / or electric field modulation caused by the hemodynamic or pulse wave event; converting the change in capacitance into an electrical signal via the transducer circuit The secondary features of the pulse waveform are captured by the electrical signal sensing and processing circuit communicatively coupled to each sensor circuit of the array and when the respective single electrode is positioned close enough to a portion of the user, and / or in response to small changes in the proximity from the single electrode to the portion of the user including the blood vessel, the proximity being in the range from zero to one millimeter (mm), the secondary features being separated from the main peak and enabling the pulse waveform to be correlated with blood pressure, whereby the transducer circuit senses the hemodynamic or pulse wave event and provides an indication of the hemodynamic parameter based on the features of the arterial pulse waveform corresponding to the electrical signal from the transducer circuit, wherein the array of sensor circuits captures the capacitance change by sensing the proximity of the portion of the user, and the electrical signal sensing and processing circuit monitors at least one of the following: a pressure difference on the order of 1 kilopascal (kPa) that indicates a change in capacitance and is detectable by the single electrode, whether or not the single electrode is in contact with the portion of the user, and a relative capacitance change on the order of 15 picofarads (pF) compared to the base capacitance of the sensor circuit, and Using a communication circuit located inside or outside the wearable device, in response to the electrical signal sensing and processing circuit, by communicating or transmitting hemodynamic monitoring data to an external circuit.

15. A device for use as part of a wearable device, the device comprising: A transducer circuit having an array of sensor circuits, wherein for each sensor circuit in the array of sensor circuits, the sensor circuit includes a single electrode configured to sense, together with the sensor circuit, a change in capacitance, the transducer circuit for converting the change in capacitance into an electrical signal, the change in capacitance in response to a pressure and / or electric field modulation caused by a hemodynamic or pulse wave event associated with a pulse waveform having a main peak; An electrical signal sensing and processing circuit, the electrical signal sensing and processing circuit operates to sense the hemodynamic or pulse wave event in response to the electrical signal from the transducer circuit, and provides an indication of the blood pressure value based on the characteristics of the arterial pulse waveform corresponding to the electrical signal from the transducer circuit, wherein an array of the sensor circuits is for capturing the capacitance change by proximity sensing of a portion of a user including a blood vessel for hemodynamic monitoring in response to a modulated fringe field line, wherein the proximity is characterized by a short distance from the single electrode to the portion of the user including the blood vessel, the short distance being in the range of zero to one millimeter, and the electrical signal sensing and processing circuit monitors at least one of the following: a pressure difference on the order of 1 kilopascal (kPa), the pressure difference indicating a change in capacitance and being detectable by the single electrode, whether or not the single electrode contacts the portion of the user, and a relative capacitance change on the order of 15 picofarads (pF) compared to the basic capacitance of the sensor circuit; and A communication circuit, the communication circuit is configured to respond to the electrical signal sensing and processing circuit by communicating or transmitting data indicating the hemodynamic monitoring, wherein when the transducer circuit is fixed by a flexible or bendable substrate to support and at least partially cover the transducer circuit and is mated with the portion of the user for hemodynamic monitoring of the user, and for each array in the array of the sensor circuits, the single electrode is positioned close enough to the portion of the user to capture the secondary features of the pulse waveform, and / or to respond to small changes in the short distance compared to the portion including the blood vessel, and can thereby electrically sense the hemodynamic or pulse wave event via the capacitance change, the secondary features being separated from the main peak and enabling the pulse waveform to be correlated with blood pressure.

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