Walk the independent claim. Fitbit's grant US11096601B2, "Optical device for determining pulse rate" (issued August 24, 2021; inventors Jung Ook Hong and Shelten Yuen), is a granted patent. Its CPC anchor A61B 5/02427 is the optical pulse-sensing class, with A61B 5/0205 cardiovascular measurement and A61B 5/681 for worn devices.

The element that does the work is the optical sensing arrangement itself. Where Fitbit's pulse-wave-analysis grant covers the analysis layer, this claim sits one level below — the optical device and arrangement that acquires the pulse signal from the wrist in the first place. It is the foundation the analysis depends on.

“Some embodiments provide a wearable monitoring device including a motion sensor and a photo (PPG) sensor. The PPG sensor includes (i) a periodic light source, (ii) a photo detector, and (iii) circuitry determining a user's heart rate from an output of the photo detector.”— U.S. Patent No. 11,096,601 source

What it reads on is the optical heart-rate sensor on the back of a fitness band or watch — the green-LED-and-photodiode arrangement that reads blood-volume changes through the skin. As a Fitbit (now Google) asset, it is part of the foundational wrist-sensing IP beneath the marketed health features.

Reading this alongside Fitbit's pulse-wave-analysis grant shows the portfolio's layered structure: an acquisition layer (this optical device) and an analysis layer (the waveform interpretation) claimed separately. That layering is deliberate — it lets the portfolio defend both the sensing and the inference, which is harder to design around than a single combined claim.

Scope discipline: the claim protects the recited optical pulse-rate device, not optical sensing generally. A wrist sensor using a materially different optical arrangement may operate outside it. The defensible element is the specific device and arrangement claimed, not the idea of optical heart-rate sensing.

Granted status places US11096601B2 among the foundational, enforceable wrist-sensing assets in a thicket that includes Apple, Samsung, Masimo, and Valencell. For a freedom-to-operate read on wrist optical sensing, the acquisition-layer claims like this one are as important as the analysis-layer claims above them.