Intersection cross-cut: watch ∩ algo-activity-classification

Axes: form_factor × algorithms

12 corpus entries disclose both tags.

Earliest disclosure: 1992

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.

Cole & Kripke et al. (1992) — automatic sleep/wake identification from wrist activity (the Cole-Kripke algorithm) (1992)

  • id: cole-kripke-1992-wrist-actigraphy-sleep
  • corpus: academic
  • form factor: watch
  • creator: Roger J. Cole / Daniel F. Kripke et al.
  • disclosure: Cole RJ, Kripke DF, Gruen W, Mullaney DJ, Gillin JC. ‘Automatic sleep/wake identification from wrist activity.’ Sleep 1992;15(5):461-469.
  • ip status: public-domain
  • sensors: sensor-accelerometer
  • algorithms: algo-sleep-staging, algo-activity-classification
  • prior art notes: Discloses an algorithm that classifies each epoch as sleep or wake from a wrist-worn activity (accelerometer) recording, validated against polysomnography — i.e. wrist actigraphy as a wearable sleep monitor. Any consumer-wearable claim reciting ‘estimating sleep/wake state from a wrist-worn accelerometer signal’ (the method underlying Fitbit/Jawbone-class sleep tracking) reads on Cole-Kripke 1992. Anchor for the accelerometry sleep-staging cross-cut; combined with the wrist form factor it makes wristworn sleep tracking obvious under [[obviousness-template]].

Sadeh et al. (1994) — activity-based sleep-wake identification (the Sadeh algorithm) (1994)

  • id: sadeh-1994-actigraphy-sleep-wake-algorithm
  • corpus: academic
  • form factor: watch
  • creator: Avi Sadeh / Katherine M. Sharkey / Mary A. Carskadon
  • disclosure: Sadeh A, Sharkey KM, Carskadon MA. ‘Activity-based sleep-wake identification: an empirical test of methodological issues.’ Sleep 1994;17(3):201-207.
  • ip status: public-domain
  • sensors: sensor-accelerometer
  • algorithms: algo-sleep-staging, algo-activity-classification
  • prior art notes: A second widely-used wrist-actigraphy sleep/wake scoring algorithm, with explicit treatment of the methodological choices (epoch length, scoring window, scaling). Prior art alongside [[cole-kripke-1992-wrist-actigraphy-sleep]] for any wearable claim reciting an actigraphy-based sleep-detection method or its parameters; both were published and validated by 1994.

Garmin Forerunner 201 (2003) — wristworn GPS running watch with pace/distance and heart-rate (strap) integration (2003)

  • id: garmin-forerunner-201-2003
  • corpus: private
  • form factor: watch
  • creator: Garmin Ltd.
  • disclosure: Garmin Ltd. ‘Forerunner 101/201’, introduced 2003 — a wrist-worn GPS receiver/watch logging pace, distance, route, and (with a paired chest strap) heart rate, with workout history and a web/PC sync. Later Garmin watches (Fenix/Forerunner with the ‘Elevate’ optical sensor, c. 2015) moved heart rate, and subsequently SpO2 (pulse ox) and respiration, onto the wrist.
  • ip status: patented
  • sensors: sensor-accelerometer, sensor-ecg, sensor-ppg
  • algorithms: algo-hr, algo-step-count, algo-calorie-estimation, algo-activity-classification
  • prior art notes: Discloses a wrist-worn GPS sport watch deriving pace, distance, and route, integrating heart rate from a paired electrode chest strap, and syncing workout history to a host — and, in later Garmin models, on-wrist optical-PPG heart rate, SpO2, and respiration. Anticipates GPS-sport-watch claims from 2003 and (for the later models) wrist-optical-vitals claims. Product-side anchor for the watch × GPS-fitness cross-cut.

Fitbit Tracker (2009) — clip-on accelerometer activity and sleep monitor (2009-10)

  • id: fitbit-tracker-2009
  • corpus: private
  • form factor: pendant
  • creator: Fitbit, Inc. (James Park, Eric Friedman)
  • disclosure: Fitbit, Inc. ‘Fitbit Tracker’, launched October 2009 — a clip-worn device with a 3-axis accelerometer estimating steps, distance, calories burned, active minutes, and sleep quality, syncing wirelessly to a web dashboard. (The wrist PPG heart-rate variant, Fitbit Charge HR, followed in January 2015.)
  • ip status: patented
  • sensors: sensor-accelerometer
  • algorithms: algo-step-count, algo-calorie-estimation, algo-activity-classification, algo-sleep-staging
  • prior art notes: Discloses a small body-worn (clip) device with a 3-axis accelerometer that estimates step count, distance, calories, active minutes, and sleep quality on-device and syncs wirelessly to a cloud dashboard. Anticipates consumer-activity-tracker claims combining ‘a body-worn accelerometer’, ‘on-device estimation of steps/calories/activity/sleep’, and ‘wireless sync to a remote service’ from 2009. Anchor for the step-count and consumer-sleep-tracking cross-cuts on the product side.

Pantelopoulos & Bourbakis (2010) — survey on wearable sensor-based systems for health monitoring and prognosis (2010-01)

  • id: pantelopoulos-bourbakis-2010-wearable-health-survey
  • corpus: academic
  • form factor: other
  • creator: Alexandros Pantelopoulos / Nikolaos G. Bourbakis
  • disclosure: Pantelopoulos A, Bourbakis NG. ‘A survey on wearable sensor-based systems for health monitoring and prognosis.’ IEEE Transactions on Systems, Man, and Cybernetics, Part C (Applications and Reviews) 2010;40(1):1-12.
  • ip status: public-domain
  • sensors: sensor-ecg, sensor-ppg, sensor-spo2, sensor-accelerometer, sensor-skin-temperature, sensor-respiration-impedance
  • algorithms: algo-hr, algo-arrhythmia-classification, algo-spo2-estimation, algo-fall-detection, algo-activity-classification
  • prior art notes: Surveys, as of 2010, the architecture and components of wearable health-monitoring systems — sensors (ECG, PPG, SpO2, accelerometry, temperature, respiration), garment- and patch- and watch-based form factors, on-body processing, wireless body-area networking, and the analytics (arrhythmia, fall, activity, deterioration prediction). Prior art establishing that the general ‘multi-sensor wearable + body-area network + cloud analytics’ system architecture and its building blocks were collected and published by 2010 — useful against later claims to the bare system architecture. General anchor.

Patel et al. (2012) — ‘A review of wearable sensors and systems with application in rehabilitation’ (2012-04-20)

  • id: patel-bonato-2012-wearable-sensors-rehab-review
  • corpus: academic
  • form factor: other
  • creator: Shyamal Patel / Hyung Park / Paolo Bonato et al.
  • disclosure: Patel S, Park H, Bonato P, Chan L, Rodgers M. ‘A review of wearable sensors and systems with application in rehabilitation.’ Journal of NeuroEngineering and Rehabilitation 2012;9:21.
  • ip status: public-domain
  • sensors: sensor-accelerometer, sensor-gyroscope, sensor-emg, sensor-ecg, sensor-ppg, sensor-pressure-skin
  • algorithms: algo-gait-analysis, algo-activity-classification, algo-fall-detection, algo-tremor-detection, algo-bradykinesia-detection, algo-posture-detection
  • prior art notes: Reviews, as of 2012, wearable inertial/EMG/pressure sensor systems for movement and physiological monitoring in rehabilitation and chronic-disease management — gait analysis, activity and posture classification, fall detection, tremor and bradykinesia quantification (Parkinson’s), with the sensor placements (foot/insole, shank, thigh, trunk, wrist, forearm) and algorithms. Prior art for wearable movement-disorder and gait-monitoring claims reciting any of the placements/analytics surveyed; collected and published by 2012. General anchor for the gait / tremor / activity cross-cuts.

Fitbit Charge HR (2015) — wristband with continuous wrist-PPG heart rate (‘PurePulse’) (2015-01-06)

  • id: fitbit-charge-hr-2015
  • corpus: private
  • form factor: watch
  • creator: Fitbit, Inc.
  • disclosure: Fitbit, Inc. ‘Fitbit Charge HR’, announced January 2015 — a wristband with ‘PurePulse’ continuous optical (green-LED PPG) heart rate, a 3-axis accelerometer, steps/distance/floors/calories/active-minutes, automatic sleep tracking, and call/text notifications.
  • ip status: patented
  • sensors: sensor-ppg, sensor-accelerometer, sensor-barometer
  • algorithms: algo-hr, algo-step-count, algo-calorie-estimation, algo-activity-classification, algo-sleep-staging
  • prior art notes: Discloses a wristband with continuous green-LED reflectance-PPG heart rate plus accelerometry and an altimeter, deriving HR, steps, floors, calories, and sleep, with phone notifications. A mainstream realization of [[mendelson-ochs-1988-reflectance-pulse-oximetry]]-geometry wrist PPG; anticipates wrist-PPG-HR-band claims from January 2015. Product-side anchor for the watch × PPG cross-cut alongside [[apple-watch-original-2015]].

Apple Watch (1st generation, 2015) — wrist green-PPG heart rate and activity (2015-04-24)

  • id: apple-watch-original-2015
  • corpus: private
  • form factor: watch
  • creator: Apple Inc.
  • disclosure: Apple Inc. ‘Apple Watch’, announced September 2014, available 24 April 2015 — a wrist-worn device with a green/infrared photoplethysmography heart-rate sensor against the dorsal wrist, accelerometer and gyroscope, and activity/exercise tracking.
  • ip status: patented
  • sensors: sensor-ppg, sensor-multi-wavelength-ppg, sensor-accelerometer, sensor-gyroscope
  • algorithms: algo-hr, algo-step-count, algo-calorie-estimation, algo-activity-classification
  • prior art notes: Discloses a wristworn device with a dorsal-wrist green-LED photoplethysmography heart-rate sensor (with IR for low-perfusion conditions), inertial sensors, and continuous HR/activity tracking. Anticipates wristworn-PPG-HR claims to the extent they postdate April 2015; combined with the much earlier PPG principle ([[hertzman-1937-photoplethysmography]]) and wrist form factor, the combination is in any case obvious under [[obviousness-template]]. Product-side anchor for the watch × PPG cross-cut.

Empatica Embrace2 (2018) — first FDA-cleared seizure-monitoring smartwatch (accelerometer + electrodermal activity) (2018-01-31)

  • id: empatica-embrace2-seizure-watch-2018
  • corpus: private
  • form factor: watch
  • creator: Empatica Inc. (Rosalind Picard, Matteo Lai, et al.)
  • disclosure: Empatica Inc. ‘Embrace2’ smartwatch, FDA-cleared January 2018 — a wrist-worn device with a 3-axis accelerometer/gyroscope, an electrodermal-activity (EDA) sensor, and a peripheral skin-temperature sensor, running an on-device classifier that detects probable generalized tonic-clonic seizures from the combined motion + EDA signature and alerts caregivers; the first FDA-cleared smartwatch for seizure monitoring. (Descends from the MIT Media Lab ‘iCalm’/’Q sensor’ EDA wristband research, Picard et al.)
  • ip status: patented
  • sensors: sensor-accelerometer, sensor-gyroscope, sensor-gsr, sensor-skin-temperature
  • algorithms: algo-seizure-detection, algo-stress-index, algo-activity-classification
  • prior art notes: Discloses a wristworn device that detects probable generalized tonic-clonic seizures by combining a motion (accelerometer/gyroscope) signature with an electrodermal-activity (sympathetic-surge) signature in an on-device classifier, and alerts caregivers — i.e. multimodal wrist-based seizure detection, distinct from the EEG-based approach. Anticipates wrist-seizure-detection claims combining ‘a wrist-worn accelerometer and an electrodermal-activity sensor’ and ‘a classifier flagging a seizure from their combined signal’ from 2018. Product-side anchor for the wrist × seizure-detection cross-cut; complementary to the EEG route in [[zanetti-aminifar-atienza-eglass-2025]] and [[chb-mit-scalp-eeg-database-2009]].

Bangle.js 2 (Espruino, 2021) — open JavaScript-app smartwatch validated in academic research (2021)

  • id: bangle-js-2-2021
  • corpus: open
  • form factor: watch
  • creator: Pur3 Ltd. (Gordon Williams, Espruino)
  • disclosure: Espruino / Pur3 Ltd. ‘Bangle.js 2’, released 2021 — Nordic nRF52840 (ARM Cortex-M4), GPS, heart rate, 3-axis accelerometer, magnetometer, pressure sensor; 4-week battery life; JavaScript app development with web-based app loader. https://banglejs.com . Validated for step counting and heart-rate measurement in academic research (multi-subject MDPI study).
  • ip status: open-permissive
  • sensors: sensor-ppg, sensor-accelerometer, sensor-magnetometer, sensor-barometer
  • algorithms: algo-hr, algo-step-count, algo-activity-classification
  • prior art notes: Discloses an open-hardware smartwatch with PPG + IMU + magnetometer + barometer + GPS, web-loaded JavaScript apps, and 4-week battery life — validated against reference devices in peer-reviewed studies for step counting and HR. As open-source hardware released in 2021 it is unencumbered prior art against patents reciting the open-firmware-platform smartwatch with this sensor set.

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.

H-Watch (Magno et al., 2024) — open-source ARM Cortex-M4F + ML + NB-IoT + energy-harvesting research smartwatch (2024)

  • id: h-watch-magno-2024
  • corpus: academic
  • form factor: watch
  • creator: Michele Magno et al. (ETH Zürich and collaborators)
  • disclosure: Magno M, et al. ‘H-Watch: A Multi-Sensor Smart Wearable for COVID-19 Symptom Monitoring with ML and Energy Harvesting.’ arXiv:2407.21501 (2024). Fully open-source smartwatch hardware + firmware for symptom monitoring: ARM Cortex-M4F MCU, on-device ML inference, NB-IoT cellular connectivity, integrated energy harvesting + battery. https://arxiv.org/abs/2407.21501
  • ip status: public-domain
  • sensors: sensor-ppg, sensor-spo2, sensor-skin-temperature, sensor-accelerometer
  • algorithms: algo-hr, algo-spo2-estimation, algo-respiratory-rate, algo-activity-classification
  • prior art notes: Discloses a fully open-source research smartwatch combining multi-sensor vitals (PPG/SpO2/temperature/IMU), on-device ML inference, NB-IoT direct cellular connectivity (no phone required), and integrated energy harvesting to extend battery life — published with full hardware design and firmware. Prior art for symptom-monitoring smartwatch claims reciting any of those elements from 2024. Establishes that the cellular-connected open-hardware ML-enabled smartwatch is a published research design.

Public domain (CC0 1.0). The corpus IS the prior art commons.

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