Bloomberg's Mark Gurman has been forecasting a "body temperature" sensor that would be coming to Apple Watch since 2022. The first iteration of a heat sensor related to ovulation cycles.

Today the U.S. Patent Office published a patent application of Apple's that reveals electronic devices with all-new temperature sensors. This patent describes a temperature sensor that will allow  users know the ambient temperature in the device's environment. For example, ambient temperature may be used in combination with fitness applications (e.g., when calculating a user's power output at different ambient temperatures), weather sensing and/or forecasting, and/or or other desired functions. The sensors may implemented in future devices such as an Apple Watch, AirPods and more.

Electronic Devices With Temperature Sensors

Apple notes in their patent application that electronic devices are often carried by users as they conduct their daily activities. For example, a user may carry an electronic device on their person throughout the day while walking, commuting, working, exercising, etc. In some situations, it may be desirable for the user to know the ambient temperature in the device's environment. For example, ambient temperature may be used in combination with fitness applications (e.g., when calculating a user's power output at different ambient temperatures), weather sensing and/or forecasting, and/or or other desired functions.

To make ambient temperature measurements, the electronic device may include an ambient temperature sensor that includes four temperature sensors, or two heat flux sensors and two temperature sensors. The temperature sensors and/or the heat flux sensors may be exposed to the same ambient temperature, but may heated/cooled to different temperatures. For example, a heater may be provided to change the temperature of one or multiple of the temperature sensors and/or heat flux sensors. These sensors may have the same or related resistance, and the ambient temperature may be calculated based on the measurements from the sensors. Alternatively, a rise in heat flux of the heated temperature sensor(s) may be measured, and a convection coefficient may be determined from a calibration curve. Based on the heat flux, the convection coefficient, and the temperature of another temperature sensor, the ambient temperature may be determined.

In general, any suitable electronic devices may include an ambient temperature sensor. As shown in FIG. 1, a wearable electronic device 10, which may be a wristwatch device, may have a housing 12, a display 14, and a strap 16. In particular, display #14 may be on a front face of wearable device #10. The wristwatch may attach to a user's wrist via strap #16. When worn on the user's wrist, a rear face of wearable device 10 (i.e., a rear surface of housing 12) may contact or be oriented toward the user's wrist. In some embodiments, device 10 may include various sensors that are in contact with the user's wrist, and the sensors may gather health or activity data (e.g., heart rate data or blood oxygen data) from the user.

Although FIG. 1 below illustrates a wristwatch device (Apple Watch), this is merely illustrative. In general, electronic device 10 may be any desired device, such as a media player, or other handheld or portable electronic device, a cellular telephone device (e.g., a smartphone/iPhone), a wristband device, a pendant device, a headphone, a speaker, a smart speaker, an ear bud or earpiece device, a head-mounted device such as glasses, goggles, a helmet, or other equipment worn on a user's head, or other wearable or miniature device, a navigation device, or other accessory, and/or equipment that implements the functionality of two or more of these devices.

Apple's patent FIG. 2 above is a diagram of an overview of an illustrative electronic device componentry including temperature sensor #120; FIG. 5 is a flowchart of illustrative steps that may be used to determine an ambient temperature by heating a heat flux sensor; FIG. 6 is a graph of an illustrative rise in heat flux; FIG. 7 is a graph of an illustrative convection coefficient calibration curve; FIG. 8 is a flowchart of illustrative steps that may be used to determine an ambient temperature by cooling a heat flux sensor.

For full details, review Apple's patent application 20250020522. Vincenzo Costanza, a Medical Engineer is listed as one of the inventors.

A year ago, Patently Apple posted a report titled "An Apple patent reveals next-gen Ultrasonic Temperature Sensors for Apple Watch & iPhone for measuring Air and Water Temperatures."  

Whether Apple will introduce one or a combination of temperature sensors into a future Apple Watch is unknown at this time.