Abstract: Methods, systems, and devices for heart rate detection are described. A method for measuring heart rate for a user may include receiving physiological data associated with the user, wherein the physiological data may include photoplethysmogram (PPG) data and motion data collected throughout a first time interval via a wearable device associated with the user. The method may include determining a set of candidate heart rate measurements within the first time interval based at least in part on the PPG data, selecting a first heart rate measurement from the set of candidate heart rate measurements based on the received motion data, and determining a first heart rate for the user within the first time interval based on the selected first heart rate measurement.

Abstract: Methods, systems, and devices for blood oxygen measurement are described. A method may include receiving, via a wearable device, a first photoplethysmogram (PPG) signal for a user acquired during a time interval using a first set of PPG sensors, and receiving a second PPG signal for the user acquired during the time interval using a second set of PPG sensors that are different from the first set of PPG sensors. The method may include comparing the first PPG signal and the second PPG signal, and determining one or more blood oxygen saturation metrics for the user during the time interval based on the comparison of the first PPG signal and the second PPG signal. The method may include causing a graphical user interface (GUI) to display an indication of the one or more blood oxygen saturation metrics.

Abstract: Methods, systems, and devices for optical signal measurement are described. A wearable electronic device may activate a first combination of optical sensors, the first combination of optical sensors including a set of transmitter sensors and a set of receiver sensors. In some cases, one or more optical sensor of the first combination of optical sensors may be positioned under a protrusion on an inner surface of the wearable electronic device. The device may measure, at the set of receiver sensors at a first time, one or more signals from the set of transmitter sensors, determine a signal quality metric associated with the one or more signals, and select a second combination of optical sensors for use at a second time based on the signal quality metric.

Abstract: Methods, systems, and devices for heart rate detection are described. A method may include receiving physiological data associated with the user, where the physiological data may include motion data and temperature data collected throughout a time interval via a wearable device associated with the user. The method may include determining a condition quality metric associated with the time interval based on the received motion data and temperature data. The condition quality metric may indicate a relative quality of the physiological data collected throughout the time interval for determination of heart rate measurements. The method may include sampling photoplethysmogram (PPG) data for the user via the wearable device based on the condition quality metric satisfying a threshold metric value and a timer satisfying a first threshold time duration. The method may include determining a heart rate measurement for the user based at least in part on the sampled PPG data.

Abstract: Methods, systems, and devices for temperature calibration are described. A device may support temperature calibration for a set of temperature sensors. For example, a wearable device may activate a set of temperature sensors associated with the wearable device. The set of temperature sensors may include a primary temperature sensor and one or more secondary temperature sensors. The wearable device may determine a trigger to calibrate the one or more secondary temperature sensors based on one or more conditions, and calibrate the one or more secondary temperature sensors using the primary temperature sensor based on the trigger. Based on the calibrating, the wearable device may process temperature data associated with a user that is received from one or more of the primary temperature sensor or the one or more secondary temperature sensors.

Abstract: Methods, systems, and devices for wearing detection are described. A method may include directing light from a first light emitting element to a first light detecting element via an optical interface, at least one of the first light emitting element or the first light detecting element dedicated to detecting a level of surface contact at the optical interface. The method may include measuring, via the first light detecting element, an amount of escaped light which escaped the optical interface, where the amount of escaped light is indicative of the level of surface contact. The method may further include controlling an activation of a second light emitting element and a second light detecting element based on the level of surface contact, at least one of the second light emitting element or the second light detecting element dedicated to measuring a physiological phenomenon at a user of the wearable device.