ARRAYED ELECTRODES IN A WEARABLE DEVICE FOR DETERMINING PHYSIOLOGICAL CHARACTERISTICS
Embodiments relate generally to electrical and electronic hardware, computer software, wired and wireless network communications, and wearable computing devices in capturing and deriving physiological characteristic data. More specifically, an array of electrodes and methods are configured to determine physiological characteristics using a wearable device (or carried device) that may be subject to motion. In one embodiment, an array of electrodes is disposed substantially in a wearable housing. At least a portion of the array including electrodes configured to either drive a first signal to a target location or receive a second signal from the target location. The second signal includes data representing one or more physiological characteristics. A sensor selector is configured to identify a subset of the electrodes adjacent to the target location and to select the subset of the electrodes from which to receive a sensor signal that includes data representing one or more physiological characteristics.
1 . A method comprising:
selecting a subset of electrodes from a plurality of subsets of electrodes, the plurality of subsets of electrodes being disposed in a wearable device;
capturing a sensor signal including data representing a motion-related signal component and a physiological-related component;
generating a motion-related signal at a motion sensor in the wearable device;
reducing a magnitude of the motion-related signal component by an amount associated with the motion-related signal to yield the physiological-related signal component; and
deriving a physiological characteristic from the physiological-related signal component.
2 . The method of claim 1 , wherein selecting the subset of electrodes comprises:
determining a first subset of electrodes is adjacent to a target location; and
selecting the first subset of electrodes as the subset of electrodes.
3 . The method of claim 2 , furthering comprising:
determining a second subset of electrodes is adjacent to the target location; and
selecting the second subset of electrodes as the subset of electrodes.
4 . The method of claim 3 , furthering comprising:
detecting motion of the wearable device.
5 . The method of claim 2 , wherein determining the first subset of electrodes is adjacent to the target location comprises:
capturing a plurality of data samples each representing a portion of a physiological characteristic;
comparing each of the plurality of data samples to data representing a profile of physiological characteristics;
determining that a data sample captured in association with the first subset of electrodes matches the profile of physiological characteristics relative to other subsets of electrodes; and
identifying the first subset of electrodes being adjacent to the target location.
6 . The method of claim 2 , wherein determining the first subset of electrodes is adjacent to the target location comprises:
tracking motion of the first subset of electrodes using an accelerometer as the motion sensor relative to a reference;
predicting that the second subset of electrodes is adjacent to the target location;
determining that a data sample captured in association with the second subset of electrodes matches the profile of physiological characteristics relative to other subsets of electrodes; and
identifying the second subset of electrodes being adjacent to the target location.
7 . The method of claim 1 , wherein deriving the physiological characteristic from the physiological-related signal component comprises:
determining a heart rate (“HR”) signal or a respiration signal as the physiological characteristic.
8 . The method of claim 7 , wherein deriving the physiological characteristic from the physiological-related signal component further comprises:
calculating a first value representing a maximal oxygen consumption (“VO2 max”) or a second value representing pulse or blood pressure based one or more of the HR and the respiration signal.
9 . The method of claim 1 , wherein capturing the sensor signal further comprises:
driving a signal through a material of which the wearable device is composed,
wherein the plurality of subsets of electrodes are encapsulated in the material.
10 . The method of claim 1 , wherein selecting the subset of electrodes further comprises:
selecting electrodes in the subset of the electrodes based on data representing a gender associated with the physiological-related signal component,
wherein the subset of the electrodes are adjacent to a target location adjacent.
11 . An apparatus comprising:
a wearable housing;
an array of electrodes disposed substantially in the wearable housing, at least a portion of the array including electrodes configured to either drive a first signal to a target location or receive a second signal from the target location, the second signal including data representing one or more physiological characteristics;
a sensor selector configured to identify a subset of the electrodes adjacent to the target location and to select the subset of the electrodes from which to receive the second signal; and
a signal controller configured to cause the first signal to drive into a first electrode of the subset of the electrodes and the second signal to be received into a second electrode of the subset of electrodes,
wherein the second signal is a sensor signal including data representing one or more physiological characteristics.
12 . The apparatus of claim 11 , wherein the signal controller is configured further to identify another subset of the electrodes adjacent to the target location and to select the another subset of the electrodes from which to receive the second signal.
13 . The apparatus of claim 12 , wherein the selection of the another subset of the electrodes indicates a displacement of the subset of the electrodes relative to the target location.
14 . The apparatus of claim 13 , further comprising:
a motion sensor configured to generate a motion signals; and
a target location determinator configured to track motion of the target location relative to a reference to form an aggregated motion of the target location, and further configured to generate data representing a predicted target location based on the aggregated motion,
wherein sensor selector is configured to use the predicted target location to select another subset of the electrodes as the subset of the electrodes adjacent to the target location.
15 . The apparatus of claim 11 , further comprising:
a motion sensor configured to generate a motion artifact signal; and
a motion artifact reducer configured to receive the sensor signal including a motion-related component and physiological-related component, and further configured to subtract the motion artifact signal from the sensor signal to remove the motion-related component to obtain the physiological-related component.
16 . The apparatus of claim 11 , further comprising:
a physiological characteristic determinator configured to derive one or more physiological signals from the sensor signal.
17 . The apparatus of claim 16 , wherein the physiological characteristic determinator is configured to determine a data signal representing either a heart rate (“HR”) or a respiration signal, or both, as the one or more physiological signals.
18 . The apparatus of claim 16 , wherein the physiological characteristic determinator is configured to calculate from the sensor signal a first value representing a maximal oxygen consumption (“VO2 max”) or a second value representing pulse or blood pressure.
19 . The apparatus of claim 11 , wherein the electrodes are configured to capacitively-couple the subset of the electrodes to the target location.
20 . The apparatus of claim 11 , wherein the wearable housing further comprises:
a material disposed between the electrodes and a surface of the wearable housing configured to confront the target location.