Apple Invents an SMI Ring that Senses Physiological Conditions such as Heart Rate, Oxygen Saturation & more
Today the US Patent & Trademark Office published a patent application from Apple that relates 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. At present, it would appear that Apple and Google are working on similar projects taking different approaches.
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 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.
Apple's invention covers devices, methods, and apparatus 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.
Apple's patent FIG. 1shows an example of a physiological monitoring system that includes a wearable device in the form of a ring and an iPhone; FIG. 2 is a close-up block diagram illustrating the physiological monitoring system with emphasis on the ring; FIG. 5A illustrates a detailed view of the positioning and interaction of the SMI sensor relative to a finger of a user; and FIG. 9 illustrates an example processes flow for using an SMI sensor to detect one or more physiological parameters of a user.
For finer details, review Apple's patent application number 20210085245.
Considering that this is a patent application, the timing of such a product to market is unknown at this time.
Google Working on a Similar Project
Coincidentally I discovered a Google patent application over the weekend that was published by USPTO on March 18, 2021 covering a similar heath device system that is in the form of a band or integrated into clothing making contact with the skin.
Google's patent abstract: "A wearable device includes at least one attachment member and an electrodermal activity (EDA) sensor comprising an integrated electrode pair physically coupled to the at least one attachment member. The electrodermal activity sensor is configured to provide an EDA signal in response to contact between the integrated electrode pair and a skin surface of a user. The integrated electrode pair includes at least two concentric electrodes radially separated by at least one insulator. Each of the at least two concentric electrodes that includes an upper surface configured to contact the skin surface of the user in order to generate the EDA signal."
Google's patent FIG. 1 below is a perspective view depicting a wearable device in the form of a smart band comprising an electrodermal activity sensor having an integrated electrode pair; FIG. 10 depicts various examples of wearable devices comprising an electrodermal activity sensor.
Google's patent application 20210077011 covers wearable devices that may include heart-rate sensors that measure a heart-rate of a user and motion sensors that measure distances, velocities, steps or other movements associated with a user using accelerometers, gyroscopes, etc. An electrocardiography sensor, for instance, can measure electrical signals (e.g., a voltage potential) associated with the cardiac system of a user to determine a heart rate.