Walk the independent claim. Fitbit's grant US10973422B2, "Photoplethysmography-based pulse wave analysis using a wearable device" (issued April 13, 2021; inventors Alexandros Pantelopoulos and Andrew Axley), is a granted patent. Its CPC anchor A61B 5/02438 is the photoplethysmography class — optical pulse sensing — surrounded by cardiovascular-measurement classes that signal the claim goes beyond heart rate.
The element that does the work is waveform analysis. A bare PPG sensor counts pulses to give heart rate. The claim's contribution is analyzing the shape of each pulse wave — its rise time, amplitude, and morphology — to extract cardiovascular features. That is the difference between a step counter with a heart-rate readout and a device making inferences about vascular health.
What it reads on is the modern fitness wearable's health-metric stack: the features built on top of optical pulse sensing that go beyond beats-per-minute. As a Fitbit (and now Google) asset, the claim sits inside a portfolio whose entire premise is turning a wrist optical sensor into a health platform.
Scope discipline: PPG itself is established medical art, and the claim does not own it. What it protects is the recited pulse-wave analysis method on a wearable. A device that reads PPG only for heart rate, without the recited waveform analysis, operates in different territory. The defensible element is the analysis, not the sensing.
Granted status places US10973422B2 among the enforceable assets in the crowded wrist-health space — a thicket that also includes Apple, Samsung, Masimo, and Valencell. For a freedom-to-operate read on any wrist-based cardiovascular metric, the pulse-wave-analysis claims are exactly the ones to map against.
The portfolio signal is consistent with Fitbit's lineage: optical sensing as the spine of a health story. This grant is the analysis layer of that story — the claim that turns a raw optical signal into a marketable health inference.