Apple has been granted various patents for an “Apple Ring.” Most have involved using such a gadget to control Macs, iPhones, iPads, Vision Pros, etc. However, a newly granted patent (number US 11992337 B2) for a “Wearable Self-mixing Interferometry Device Used To Sense Physiological Conditions” suggests it could also used to monitor a wearer’s health.
About the patent
The patent relates 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.
In the patent Apple notes that 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.
However, Apple says that, 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 apparently thinks an “Apple Ring” could perform health measurements more accurately.
Summary of the patent
Here’s Apple’s abstract of the patent: “A wearable electronic device including a housing that is worn by a user and a SMI sensor contained within the housing. The SMI sensor may include an emitter that outputs coherent light toward the skin of a user when the housing is worn by the user. The SMI sensor may also include a detector that detects a portion of the coherent light reflected towards the sensor and generates electrical signals that indicate displacements of the skin based on the portion of coherent light received at the detector. The housing may include a transmitter that is operatively coupled with the SMI sensor and is configured to transmit physiological data to a receiving device based on electrical signals output from the SMI sensor.”
