What was the key innovation required to validate a truly reliable stress wearable device over simple fitness trackers?

Creating algorithms correlating physiological drift with user-reported stress scores.

A fundamental hurdle in developing reliable stress monitoring wearables, distinguishing them from easily validated devices like step counters, is the intensely subjective nature of stress itself. Therefore, the crucial innovation revolved around solving the objective validation problem: demonstrating that the device's readings accurately reflected an internal, subjective state. This was achieved by creating intricate algorithms designed to correlate subtle physiological changes—such as shifts in skin temperature or sweat composition—with stress scores manually reported by the user over extensive periods of use.