Apple announced the Watch Series 12 and Ultra 4 today. Both include a new "Health Sensing System" and S11 chip that give the devices the “most accurate heart rate sensing in a wearable," Apple claimed during its fall event.
Both watches will use the new S11 chip alongside the new "Health Sensing System," allowing the watches to deliver higher-frequency heart rate and heart rate variability (HRV) measurements than prior Apple Watches.
The Health Sensing System includes redesigned photodiodes organized in a ring to capture light more efficiently and a larger electrode surface area for better skin contact. Additionally, the green LEDs on each Watch's optical heart sensor are supposed to be bigger and more power-efficient and measure the user's heart rate every five seconds. Users will be able to view their heart rate in real time with a new heart rate watch face special feature (also known as a complication).
