FIELD

Embodiments described herein relate generally to devices that include self-mixing interferometry sensors and, more particularly, to wearable devices that use one or more self-mixing interferometry sensors to sense a movement of the skin of a user and/or determine one or more physiological conditions, such as a heart rate, from the movement of the skin.

BACKGROUND

Electronic devices, such as smartphones, watches, and other wearable devices, may include sensor systems to detect and/or monitor one or more physiological conditions of a user. Wearable electronic device may measure and/or monitor heart rates, blood oxygen saturation, blood pressure, sleep cycles, body temperatures, and so on. These electronic devices may include one or more sensor systems that derive a physiological condition of the user (e.g., blood oxygen saturation, heart rate, and so on) by applying a stimulus such as light and detecting a response from the stimuluses interaction with the body. Sensor systems may use a light emitting diodes (LEDs) to transmits light such as infrared light into the a blood vessel and detect the response of the light after interacting with the blood. In such cases, one or more conditions of the blood (e.g., flow rate, oxygen content, and so on) may affect the transmitted light, which may be used to derive a physiological parameter such as a blood oxygen saturation. In many cases, the accuracy and/or quality of measurements from these sensor systems depends on light being transmitted into the skin to interact with one or more blood vessels. Thus, these sensors may be sensitive to positioning on the user and or require robust circuitry to detect and/or processes the signals received from a user's body.

SUMMARY

Embodiments of the systems, devices, methods, and apparatus described in the present disclosure are directed to the configuration and operation of a device that includes an electronic device having one or more self-mixing interferometry sensors. The self-mixing interferometry sensor(s) may be used to measure one or more physiological conditions of a user. The electronic device may include a housing configured to be worn by a user and a sensor contained within the housing. The sensor may include an emitter positioned within the housing and configured to output coherent light toward a skin of the user when the housing is worn by the user. The sensor may also include a detector configured to detect a portion of coherent light reflected towards the sensor and generate electrical signals that indicate displacements of the skin based on the portion of coherent light. The electronic device may further include a transmitter operatively coupled with the sensor and configured to transmit physiological data based on the electrical signals.

Embodiments may further be directed to an electronic device including a sensor where the sensor includes an emitter configured to output coherent light toward a skin of a user when the electronic device is worn by the user, and a detector configured to detect a portion of the coherent light reflected from the user and generate electrical signals based on the portion of the coherent light. The electronic device may also include a housing containing the sensor and configured to position the emitter at a first distance from the skin of a user. The housing may include a user interface configured to contact the skin of the user. The electronic device may further include a transmitter positioned within the housing and operatively coupled with the sensor. The transmitter may be configured to transmit physiological data based on the electrical signals.

Additional embodiments may be directed to a method for tracking movement of the skin of a user. The method may include transmitting coherent light from a self-mixing interferometer (SMI) and towards a skin surface of a user; detecting a portion of the coherent light reflected towards the SMI; generating, at the SMI, an electrical signal based on the detected portion of the coherent light; determining displacements of the skin based on the detected portion of the coherent light; and outputting a heart rate for the user based on the displacements of the skin.

