Proximity sensor circuits and related sensing methods
View Patent ↗Various embodiments include an apparatus and methods of use of a proximity sensor. An example apparatus includes a transducer circuit having a sensor circuit, the sensor circuit including an electrode, an electrical-signal sensing circuit, a substrate to support and at least partially enclose the transducer circuit and the electrical-signal sensing circuit, and a communication circuit. The transducer circuit converts changes in capacitance into electrical signals, the changes in capacitance being carried by the electrode and being responsive to pressure and/or electric field modulations attributable to hemodynamic or pulse-wave events. The electrical-signal sensing circuit senses the events in response to the electrical signals from the transducer circuit. The substrate can conform to a portion of a user and locate the sensor circuit sufficiently close to the user's skin for electrically sensing the hemodynamic or pulse-wave events. The communication circuit responds to the electrical-signal sensing circuit by sending data indicative of the hemodynamic monitoring.
1 . A wearable apparatus comprising:
a transducer circuit including a sensor circuit to sense changes in capacitance through a user's skin without relying on an active portion of the sensor circuit being in contact with the user's skin where the changes are to be sensed and being configured to convert the changes in capacitance into electrical signals;
a layered portion, as part of the sensor circuit, including a dielectric layer adjacent to or stacked with a conductive electrode layer and including one or more spacers to control or set a distance between the active portion of the sensor circuit and skin of the user, the changes in capacitance being responsive to at least one of pressure and electric field modulations attributable to hemodynamic or pulse-wave events of an arterial pulse waveform manifesting primary peaks as pulse-waveform maxima and minima and manifesting one or more subtle features separated from the primary peaks and in between the pulse-waveform maxima and minima;
an electrical-signal sensing circuit to sense the primary peaks as pulse-waveform maxima and minima and to sense the one or more subtle features separated from the primary peaks and in between the pulse-waveform maxima and minima in response to the electrical signals from the transducer circuit;
a substrate to support and at least partially enclose the transducer circuit and the electrical-signal sensing circuit, and to conform to a portion of the user and position the conductive electrode layer sufficiently close to the user's skin to facilitate the sensor circuit sensing the changes in capacitance; and
a communication circuit to respond to the electrical-signal sensing circuit by conveying data, indicative of the one or more subtle features.
2 . The wearable apparatus of claim 1 , wherein the transducer circuit further includes a plurality of sensor circuits and a plurality of respectively-corresponding conductive electrode layers, each of the sensor circuits including only one conductive electrode layer, wherein the pressure change is indicative of the capacitance change.
3 . The wearable apparatus of claim 1 , wherein the sensor circuit is to capture the capacitance change through proximity sensing of the skin of the user in response to at least one of:
modulating distances between the user's skin and the sensor circuit; and
modulating fringe field lines.
4 . The wearable apparatus of claim 3 , wherein the communication circuit is further to communicate the captured capacitance changes attributable to the hemodynamic or pulse-wave events to external processing circuitry.
5 . The wearable apparatus of claim 1 , wherein the transducer circuit is to be operated using a floating ground while the user wears the wearable apparatus on a portion of the user's body detached from any wires between the user's body and other electrical or electronics circuitry that is not coupled to the user's body and not part of the wearable apparatus and while the changes in capacitance are being sensed, and wherein the data indicative of the hemodynamic monitoring is also indicative of changes in at least one of the following: diastolic blood pressure, systolic blood pressure, and arterial stiffness.
6 . The wearable apparatus of claim 1 , wherein sufficiently close to the user's skin corresponds to the distance, while the user wears the wearable apparatus on a portion of the user's body detached from any wires between the user's body and other electrical or electronics circuitry that is not coupled to the user's body and not part of the wearable apparatus, relative to the portion of the user's body, wherein the distance is at most 1 millimeter (mm) away from the skin.
7 . The wearable apparatus of claim 1 , wherein comprising:
the transducer circuit has an array of electrical-signal sensing circuits, each of which is to sense and convert changes in capacitance into electrical signals, the changes in capacitance being responsive to at least one of pressure and electric field modulations attributable to hemodynamic or pulse-wave events sensed through the user's skin, without relying on the active portion of the electrical-signal sensing circuits being in contact with the user's skin where the changes are to be sensed;
and
the communication circuit is to respond to the array of electrical-signal sensing circuits by sending data indicative of the hemodynamic monitoring, wherein different ones of the electrical-signal sensing circuits have different respective sensitivity levels.
8 . The wearable apparatus of claim 7 , wherein the transducer circuit includes an electrical-signal sensing circuit having only a single conductive electrode layer and being configured to monitor relative capacitance changes in a range of plus and minus 15 picofarad (pF) from a base capacitance of the electrical-signal sensing circuit.
9 . The wearable apparatus of claim 1 , further including at least two electrical-signal sensing circuits, wherein each of the electrical-signal sensing circuits includes a respective layered portion having a dielectric layer adjacent to or stacked with a conductive electrode layer, and the electrical-signal sensing circuits are cooperatively configured to provide a differential mode realized by subtracting out artifacts in response to the hemodynamic monitoring.
10 . The wearable apparatus of claim 9 , wherein the respective conductive electrode layers of the at least two electrical-signal sensing circuits are respectively associated with different characteristics based on at least one of electrode geometry and dielectric layers used with an associated one of the at least two electrical-signal sensing circuits.
11 . The wearable apparatus of claim 10 , wherein the at least two electrical-signal sensing circuits have encapsulants to set a sensitivity level.
12 . The wearable apparatus of claim 1 , further including a passively or inductively powered circuit to provide power to at least the electrical-signal sensing circuit.
13 . The wearable apparatus of claim 1 , wherein a portion of the dielectric layer encapsulates the layered portion.
14 . The wearable apparatus of claim 1 , wherein the substrate and the layered portion are configured as part of a user accessory and further configured to be sufficiently flexible for conforming to a wrist of or other body portion of the user.
15 . The wearable apparatus of claim 1 ,
wherein the sensor circuit includes a substrate portion that is to be mechanically constrained to the user's skin or another portion of the user's body with an adhesive applied to a perimeter region of the substrate portion, and the communication circuit is to send data, indicative of the one or more subtle features separated from the primary peaks and in between the pulse-waveform maxima and minima, to an external circuit that includes at least one of a display and a data-processor.
16 . The wearable apparatus of claim 1 , wherein the electrical-signal sensing circuit is further to determine hemodynamic parameters of the user or the user's heart using the hemodynamic or pulse-wave events.
17 . The wearable apparatus of claim 1 , wherein the substrate is characterized as being non-conductive and is configured to be worn on a wrist by being at least one of flexible and bendable, for conformance around the wrist.
18 . The wearable apparatus of claim 1 , wherein the layered portion is characterized in terms of thickness and flexibility for the sensor circuit to capture the hemodynamic or pulse-wave events in response to the electrical signals via at least one of a: pressure change in a range from 0.3 kilopascal to 1 kilopascal, and a capacitance change in a range defined as plus and minus 15 picofarads.
19 . A method for hemodynamic monitoring via a wearable apparatus, the method comprising:
using a flexible or bendable substrate to secure a transducer circuit having at least one sensor circuit to sense changes in capacitance sensed through a user without relying on an active portion of the at least one sensor circuit being in contact with the user where the changes are to be sensed, the at least one sensor circuit including an electrical-signal sensing circuit and including a layered portion, wherein the layered portion includes at least one conductive electrode layer and at least one other different material layer and includes one or more spacers to control or set a distance between the active portion of the at least one sensor circuit and skin or other tissue of the user, and the substrate supporting and at least partially enclosing the transducer circuit and the electrical-signal sensing circuit, and conforming to the skin or the other tissue of the user and therein locating the conductive electrode layer sufficiently close to the skin or the other tissue with the layered portion being characterized in terms of thickness and flexibility for electrically sensing hemodynamic or pulse-wave events of an arterial pulse waveform manifesting primary peaks as pulse-waveform maxima and minima and manifesting one or more subtle features separated from the primary peaks and in between the pulse-waveform maxima and minima;
via the transducer circuit, converting the changes in capacitance into electrical signals, the changes in capacitance being responsive to at least one of pressure and electric field modulations attributable to the one or more features,
via the electrical-signal sensing circuit, sensing the one or more features in response to the electrical signals from the transducer circuit, and
using a communication circuit, within or outside the wearable apparatus, to respond to the electrical-signal sensing circuit by conveying data indicative of the one or more subtle features.
20 . The method of claim 19 , wherein the layered portion is characterized in terms of thickness and flexibility for the at least one sensor circuit to capture the hemodynamic or pulse-wave events via the electrical signals via at least one of a: pressure change in a range from 0.3 kilopascal to 1 kilopascal, and a capacitance change in a range defined as plus and minus 15 picofarads.
21 . The method of claim 19 , further including the communication circuit presenting or sending data indicative of the primary peaks as pulse-waveform maxima and minima and the one or more subtle features separated from the primary peaks and in between the pulse-waveform maxima and minima.