Intersection cross-cut: sensor-spo2 ∩ algo-step-count

Axes: sensors × algorithms

4 corpus entries disclose both tags.

Earliest disclosure: 2014-02-25

These entries are the direct inputs to OBVIOUSNESS_TEMPLATE.md. Any patent claim combining these two elements is anticipated or rendered obvious by the chain below.

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Bragi Dash (2014) — the first true ‘hearable’: in-ear PPG heart rate, accelerometer, storage and touch control inside wireless earbuds (2014-02-25)

• id: bragi-dash-2014
• corpus: private
• form factor: earbud
• creator: Bragi GmbH
• disclosure: Bragi GmbH. ‘The Dash’ wireless smart earphones, crowdfunded February 2014 (shipped 2016) — fully wireless in-ear earbuds with a reflectance-PPG heart-rate sensor and oxygen-saturation estimation against the ear-canal wall, a 3-axis accelerometer (head-gesture and step/activity tracking), 4 GB onboard music storage, bone-conduction microphone, and capacitive touch control.
• ip status: patented
• sensors: sensor-ppg, sensor-spo2, sensor-accelerometer, sensor-microphone-bone
• algorithms: algo-hr, algo-spo2-estimation, algo-step-count, algo-activity-classification
• prior art notes: Discloses fully-wireless in-ear earbuds with a reflectance-PPG heart-rate and SpO2 sensor against the ear-canal wall, an accelerometer for head-gesture and step/activity tracking, onboard music storage, a bone-conduction microphone, and capacitive touch control — i.e. physiological sensing integrated into wireless earbuds. Anticipates hearable claims combining ‘a wireless earbud housing’, ‘an in-ear PPG/SpO2 sensor’, ‘an accelerometer for activity or head gesture’, and ‘on-device media and controls’ from 2014. Product-side anchor for the earbud × PPG cross-cut.

Withings ScanWatch (2020) — hybrid analog watch with PPG, SpO2 pulse oximetry, single-lead ECG, and accelerometer (2020-01-05)

• id: withings-scanwatch-2020
• corpus: private
• form factor: watch
• creator: Withings SA
• disclosure: Withings (Nokia/Withings). ‘ScanWatch’, announced January 2020 (CE-marked 2020; FDA cleared 2022) — a hybrid analog wristwatch integrating a reflectance-PPG sensor (heart rate, irregular-rhythm screening), an SpO2 (pulse-oximetry) measurement, a single-lead ECG (back electrode plus a bezel electrode touched by the opposite hand, with AF detection), a 3-axis accelerometer, and an altimeter — with sleep and activity tracking.
• ip status: patented
• sensors: sensor-ppg, sensor-spo2, sensor-ecg, sensor-accelerometer, sensor-barometer
• algorithms: algo-hr, algo-spo2-estimation, algo-afib-detection, algo-arrhythmia-classification, algo-sleep-staging, algo-step-count, algo-respiratory-rate
• prior art notes: Discloses a wristwatch combining reflectance-PPG heart rate, pulse-oximetry SpO2, a single-lead ECG with AF detection, accelerometry, and an altimeter, with sleep-apnea screening (from the SpO2/respiration signals) — multiple regulated cardiorespiratory measurements in one consumer watch. Anticipates multi-modal medical-smartwatch claims reciting combinations of wrist PPG-HR + wrist SpO2 + single-lead ECG from 2020. Product-side anchor for the watch × {PPG, SpO2, ECG} multi-sensor cross-cut.

Open-Watch (Salar Motlaqolahi, 2021) — fully documented open STM32 smartwatch (BSc thesis) (2021)

• id: smotlaq-open-watch-2021
• corpus: open
• form factor: watch
• creator: Salar Motlaqolahi
• disclosure: Motlaqolahi S. ‘Open-Watch’ — fully open-source smartwatch released as BSc thesis output (MIT license). Hardware: STM32 ARM Cortex-M MCU, MPU6050 6-axis IMU, MAX30102 reflectance PPG + SpO2, 4-layer PCB sponsored by PCBWay, full schematics + Gerbers + firmware published. https://github.com/SMotlaq/open-watch
• ip status: open-permissive
• sensors: sensor-ppg, sensor-spo2, sensor-accelerometer, sensor-gyroscope
• algorithms: algo-hr, algo-spo2-estimation, algo-step-count
• prior art notes: Discloses, as an MIT-licensed open-hardware smartwatch with full PCB design files (4-layer, PCBWay-sponsored fabrication) and firmware published, a wrist-worn device with reflectance PPG + SpO2 + 6-axis IMU + MCU + display. Demonstrates that the entire smartwatch design — schematic, layout, firmware — can be reproduced from undergraduate-thesis-level public work, defeating any claim that the integrated smartwatch is novel as a combination.

HealthyPi Move (ProtoCentral, 2026) — open-source medical-grade smartwatch (2024)

• id: healthypi-move-2026
• corpus: open
• form factor: watch
• creator: ProtoCentral Electronics
• disclosure: ProtoCentral Electronics (Bengaluru, India). ‘HealthyPi Move’ fully open-source AMOLED smartwatch — Crowd Supply campaign launched 2024, units shipping 15 May 2026. Sensors: single-lead ECG, dual-site PPG (wrist + finger), SpO2, blood-pressure trending, EDA/GSR, heart rate, HRV, respiration rate (derived), body temperature, 6-axis IMU. Compute: Nordic nRF5340 (dual ARM Cortex-M33). Display: AMOLED, 300 mAh battery. Companion app: Flutter, runs on Android/iOS/macOS/Windows/Linux, all data stored locally. Hardware design, firmware (Zephyr RTOS on nRF Connect SDK), and companion app all open-source. https://www.crowdsupply.com/protocentral/healthypi-move
• ip status: open-permissive
• sensors: sensor-ecg, sensor-ppg, sensor-spo2, sensor-multi-wavelength-ppg, sensor-gsr, sensor-accelerometer, sensor-gyroscope, sensor-skin-temperature
• algorithms: algo-hr, algo-hrv, algo-spo2-estimation, algo-respiratory-rate, algo-pwv-bp-estimation, algo-sleep-staging, algo-activity-classification, algo-step-count
• prior art notes: Discloses, as fully open-source hardware and firmware (CC and MIT-style licensing across components), a wrist-worn smartwatch with the full consumer-medical sensor stack: single-lead ECG between back-of-watch electrode and a finger-touch electrode; multi-wavelength reflectance PPG with SpO2 and BP-trending; EDA/GSR; skin temperature; 6-axis IMU; on-device Zephyr-RTOS application; AMOLED display; all-local data storage via cross-platform Flutter app. Anticipates wrist-multi-sensor-watch claims from 2024-2026 to the extent they recite combinations of these elements; as open prior art it is unencumbered and any patent claim reciting these combinations must distinguish over HealthyPi Move’s specific implementation. The product-side anchor for the ‘open watch with the full sensor stack’ cross-cut.