Wearable blood-oxygen sensing — the pulse-oximetry feature now common in smartwatches and rings — is classified under Cooperative Patent Classification group A61B 5/1455. The CPC scheme defines A61B 5/1455 as covering the measurement of blood characteristics in vivo "using optical sensors, e.g. spectral photometrical oximeters." That is the optical-oximetry coordinate: any filing whose method shines light through or against tissue and reads the absorption to estimate oxygen saturation lands here.

The group sits inside a clear hierarchy. Its parent, A61B 5/145, covers "measuring characteristics of blood in vivo, e.g. gas concentration or pH-value," and that in turn sits under A61B 5/00, "measuring for diagnostic purposes... Identification of persons." So the full lineage of a pulse-oximetry symbol reads: diagnostic measurement (A61B 5/00) → blood characteristics in vivo (A61B 5/145) → optical oximeters (A61B 5/1455). For wrist-worn reflective sensors specifically, filings frequently carry the further-indented A61B 5/14552, and because oximetry devices typically also derive a pulse, many add A61B 5/024, "measuring pulse rate or heart rate."

"using optical sensors, e.g. spectral photometrical oximeters"— CPC scheme, A61B 5/1455, source

How a real wrist-oximetry patent is classified

The classification is concrete on an actual grant. US9730622B2, titled "Wearable pulse oximetry device" (issued 2017, assignee Oxitone Medical Ltd.), carries CPC symbols including A61B 5/14552 (reflective optical oximetry), A61B 5/02416 and A61B 5/02438 (photoplethysmographic / cardiovascular measurement), A61B 5/14551 (the photoplethysmography sibling), and A61B 5/681 / A61B 5/6824 for the wrist-worn constructional aspect. That spread is typical of the field: the optical-oximetry symbol describes the measurement principle, while the A61B 5/02x symbols describe the pulse/PPG signal and the A61B 5/68x symbols describe the worn form factor.

The claim makes the fit obvious. Independent claim 1 recites "A pulse oximetry device, the device comprising: a wrist band; at least two light sources having different wavelengths; at least one detector responsive to said different wavelengths; and a structure coupled to the wrist band and adapted to fixate at a distal end of the ulna at a fixated area... and said at least one detector is positioned to detect light emitted from said at least two light sources." Two light sources of different wavelengths and a responsive detector is the textbook optical-oximetry arrangement A61B 5/1455 names; the wrist band and ulna-fixating structure are the wearable elements that pull in the A61B 5/68x worn-sensor symbols.

The two-wavelength element in that claim is not incidental — it is the physical basis of oximetry, and it is what ties the device to A61B 5/1455 specifically rather than to a generic optical-sensing symbol. Pulse oximetry estimates oxygen saturation by comparing how oxygenated and deoxygenated hemoglobin absorb light at two different wavelengths, typically a red and an infrared source. A device that uses a single wavelength to detect a pulse waveform is doing photoplethysmography (the A61B 5/14551 sibling) but not oximetry; the second wavelength is what enables the saturation calculation, which is why the oximetry symbol A61B 5/1455 and its A61B 5/14552 reflective child sit one rung apart from the plain PPG symbol. Reading the CPC symbols on a wearable health patent therefore tells you, at a glance, whether the filing claims oxygen-saturation measurement or only heart-rate-type pulse sensing.

Where A61B 5/1455 sits, and what the neighboring symbols mean

Because the A61B 5 subclass is dense, a quick map helps. A61B 5/00 is the broad diagnostic-measurement roof. A61B 5/024 is pulse-rate or heart-rate measurement. A61B 5/145 covers measuring blood characteristics in vivo, and A61B 5/1455 is its optical-sensor branch — the oximetry coordinate — with A61B 5/14551 for photoplethysmography and A61B 5/14552 for reflective (as opposed to transmissive) optical measurement, the mode used at the wrist where light cannot pass through the limb. The A61B 5/02x cluster (A61B 5/02416, A61B 5/02427, A61B 5/02438) covers the cardiovascular and photoplethysmographic signal-processing aspects, and the A61B 5/68x cluster (A61B 5/681, A61B 5/6824, A61B 5/6831) covers how the sensor is constructed and held against the body. A consumer wrist wearable that measures both SpO2 and heart rate will typically carry symbols from all four neighborhoods at once, and the combination is itself a fingerprint of the device's capabilities.

Reading the wearable-sensing landscape through the class

For portfolio mapping, A61B 5/1455 is the symbol that isolates optical blood-oxygen work from the larger A61B 5/00 diagnostic universe. A search confined to A61B 5/1455 (and A61B 5/14551/14552 beneath it) surfaces the emitter-detector oximetry filings rather than the broad sea of general physiological-monitoring patents. Pairing it with A61B 5/024 narrows further to devices that derive both oxygen saturation and heart rate — the combination most consumer wrist wearables ship. The worn-sensor symbols (A61B 5/681, A61B 5/6824, A61B 5/6831) then separate wrist and finger form factors from clinical bench oximeters.

A couple of classification habits keep the reading clean. CPC attaches several symbols to one document, so a wearable-oximetry patent will rarely sit on A61B 5/1455 alone — expect the optical-oximetry symbol plus PPG symbols plus worn-sensor symbols, as the Oxitone grant shows. The presence of A61B 5/1455 (or its 14551/14552 children) is the strongest single signal that a filing concerns optical pulse oximetry; A61B 5/024 signals heart-rate derivation; and A61B 5/68x signals the wearable mounting. When the question is "what CPC class covers wearable pulse oximetry," the precise answer is A61B 5/1455 for the optical-oximetry group and A61B 5/14552 for reflective wrist sensors — and US9730622B2 shows exactly how those symbols attach to a real wrist-oximeter claim.