Apple Watch Ultra 4 Adds 32-Electrode Sensor Array and Real-Time Readiness Score

Apple's new $799 Watch Ultra 4 pairs a redesigned sensor array—32 electrodes arranged like flower petals—with the new S11 chip, enabling heart-rate readings every 5 seconds and HRV checks every 5 minutes, far more frequent than prior models. That increased sampling powers a new Readiness score that updates throughout the day rather than relying mainly on overnight data, plus a Daytime toggle in the Vitals app to view daytime alongside nighttime metrics.