Cross-cut: `sensor-ppg`

Axis: sensors

39 corpus entries disclose this tag.

Earliest disclosure: 1937

Listed in chronological order. Each entry’s prior_art_notes and disclosure_citation constitute the citeable prior art material.

Hertzman (1937) — photoelectric plethysmography (the origin of PPG) (1937)

id: hertzman-1937-photoplethysmography
corpus: academic
form factor: other
creator: Alrick B. Hertzman
disclosure: Hertzman AB. ‘Photoelectric plethysmography of the fingers and toes in man.’ Proceedings of the Society for Experimental Biology and Medicine 1937;37(3):529-534.
ip status: public-domain
sensors: sensor-ppg
prior art notes: Coins and demonstrates ‘photoelectric plethysmography’ — measuring the pulsatile change in transmitted/reflected light through perfused tissue to track blood volume pulse. This is the disclosure root of the entire PPG wearable space: every claim reciting ‘a photoplethysmography sensor’ or ‘a light source and a photodetector arranged to measure a blood volume pulse in tissue’ reads on Hertzman 1937. As § 102 prior art for the bare PPG principle it is dispositive; combined with any form-factor disclosure it renders the form-factor+PPG combination obvious under [[obviousness-template]].

Peñáz (1973) — the volume-clamp (vascular unloading) method of continuous finger blood pressure (1973)

id: penaz-1973-volume-clamp-finger-bp
corpus: academic
form factor: other
creator: Jan Peñáz
disclosure: Peñáz J. ‘Photoelectric measurement of blood pressure, volume and flow in the finger.’ Digest of the 10th International Conference on Medical and Biological Engineering, Dresden, 1973, p. 104. (Basis of the Finapres / volume-clamp continuous BP monitors.)
ip status: public-domain
sensors: sensor-ppg, sensor-cuffless-bp-volume-clamp, sensor-pressure-skin
algorithms: algo-pwv-bp-estimation
prior art notes: Discloses the volume-clamp / vascular-unloading method: a finger cuff servo-controlled by a photoplethysmographic feedback loop to hold the arterial volume constant, so the applied counter-pressure tracks the arterial pressure waveform continuously and non-invasively. Any cuffless/continuous-BP wearable claim reciting ‘a photoplethysmographic feedback loop controlling an applied pressure to maintain constant vascular volume’ reads on Peñáz 1973. Anchor for the volume-clamp cuffless-BP cross-cut (the finger/ring form-factor variants are obvious combinations under [[obviousness-template]]).

Aoyagi (1974) — two-wavelength pulse oximetry principle (1974)

id: aoyagi-1974-two-wavelength-pulse-oximetry
corpus: private
form factor: other
creator: Takuo Aoyagi (Nihon Kohden)
disclosure: Aoyagi T, et al. — the pulsatile two-wavelength (red/infrared) ratio method for non-invasive arterial oxygen saturation, presented at the 13th Annual Meeting of the Japan Society of Medical Electronics and Biological Engineering (1974); commercialized as the Nihon Kohden ‘Ear Oximeter OLV-5100’ (1975) and Minolta ‘Oximet MET-1471’ (1977). History documented in Severinghaus JW, Honda Y. ‘History of blood gas analysis. VII. Pulse oximetry.’ J Clin Monit 1987;3(2):135-138.
ip status: patented
sensors: sensor-spo2, sensor-ppg, sensor-multi-wavelength-ppg
algorithms: algo-spo2-estimation
prior art notes: Discloses the pulsatile two-wavelength ratiometric method that underlies every non-invasive SpO2 device: comparing the AC/DC ratios of light absorbance at (typically) red ~660 nm and infrared ~940 nm through pulsatile tissue to compute arterial oxygen saturation. Any wearable claim reciting ‘a first and second light source at distinct wavelengths and a photodetector configured to compute oxygen saturation from a ratio of pulsatile components’ reads on this. § 102 prior art for the SpO2 principle from 1974; the wrist/ring/earbud form-factor variants are obvious combinations under [[obviousness-template]].

Geddes et al. (1981) — pulse transit time as an indicator of arterial blood pressure (1981-01)

id: geddes-1981-pulse-transit-time-bp
corpus: academic
form factor: other
creator: Leslie A. Geddes et al. (Purdue)
disclosure: Geddes LA, Voelz MH, Babbs CF, Bourland JD, Tacker WA. ‘Pulse transit time as an indicator of arterial blood pressure.’ Psychophysiology 1981;18(1):71-74.
ip status: public-domain
sensors: sensor-ecg, sensor-ppg, sensor-cuffless-bp-ptt
algorithms: algo-pwv-bp-estimation
prior art notes: Establishes that pulse transit time — the delay between a proximal timing reference (e.g. the ECG R-wave) and the arrival of the pulse at a distal site (e.g. a finger PPG) — varies inversely with arterial blood pressure, and can therefore be used to estimate BP without a cuff. Any cuffless-BP wearable claim reciting ‘estimating blood pressure from a pulse transit time (or pulse arrival time / pulse wave velocity) derived from two physiological signals’ reads on Geddes 1981. Earliest anchor for the PTT-cuffless-BP cross-cut; [[mukkamala-2015-ptt-cuffless-bp-review]] is the modern survey.

Mendelson & Ochs (1988) — reflectance-mode pulse oximetry / skin-reflectance PPG (1988-10)

id: mendelson-ochs-1988-reflectance-pulse-oximetry
corpus: academic
form factor: other
creator: Yitzhak Mendelson / Burt D. Ochs
disclosure: Mendelson Y, Ochs BD. ‘Noninvasive pulse oximetry utilizing skin reflectance photoplethysmography.’ IEEE Transactions on Biomedical Engineering 1988;35(10):798-805.
ip status: public-domain
sensors: sensor-ppg, sensor-spo2, sensor-multi-wavelength-ppg
algorithms: algo-spo2-estimation, algo-hr
prior art notes: Establishes pulse oximetry by reflectance (light source and detector on the same side of the tissue) rather than transmission — the geometry every wrist, forehead, ring, chest, and earbud PPG/SpO2 wearable uses, since those sites cannot be transilluminated. Any wearable-SpO2 claim reciting ‘a reflectance photoplethysmography sensor’ or ‘a light source and photodetector arranged on a common surface against the skin’ reads on Mendelson & Ochs 1988. Anchor for the reflectance-PPG/SpO2 cross-cut on non-fingertip sites.

Task Force of the ESC and NASPE (1996) — heart rate variability: standards of measurement (1996-03)

id: esc-naspe-1996-hrv-standards
corpus: standards
form factor: other
creator: Task Force of the ESC and NASPE
disclosure: Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. ‘Heart rate variability: standards of measurement, physiological interpretation, and clinical use.’ Circulation 1996;93(5):1043-1065 (also European Heart Journal 1996;17:354-381).
ip status: standards
sensors: sensor-ecg, sensor-ppg
algorithms: algo-hrv, algo-stress-index
prior art notes: Standardizes the time-domain (SDNN, RMSSD, pNN50, …) and frequency-domain (VLF/LF/HF, LF/HF ratio) measures of heart rate variability, their computation from an interbeat-interval series, and their physiological interpretation. Any wearable claim reciting ‘computing a heart-rate-variability metric (e.g. RMSSD, LF/HF) from a sequence of interbeat intervals’ rests on metrics standardized here. Anchor for the HRV cross-cut; applicable whether the interbeat intervals come from ECG or PPG.

Webster (ed.) (1997) — ‘Design of Pulse Oximeters’ (1997)

id: webster-1997-design-of-pulse-oximeters
corpus: academic
form factor: other
creator: John G. Webster (ed.)
disclosure: Webster JG (ed). ‘Design of Pulse Oximeters.’ Series in Medical Physics and Biomedical Engineering, IOP Publishing / Institute of Physics, 1997. ISBN 0-7503-0467-7.
ip status: public-domain
sensors: sensor-spo2, sensor-ppg
algorithms: algo-spo2-estimation, algo-hr
prior art notes: The standard engineering reference on pulse oximeter design as of 1997 — LED selection and drive, photodiode front-ends, the ratio-of-ratios calibration, motion-artifact handling, low-perfusion behavior, calibration-curve construction. Prior art for wearable-SpO2 claims to the extent they recite implementation details (wavelength choice, AC/DC ratio computation, calibration-curve mapping, artifact rejection) covered here; these were textbook-level public knowledge by 1997.

MIT wearable ring sensor (Rhee, Yang, Asada) — finger-ring PPG for ambulatory monitoring (2001-07)

id: asada-mit-wearable-ring-sensor-2003
corpus: academic
form factor: ring
creator: Sokwoo Rhee / Boo-Ho Yang / Haruhiko Harry Asada (MIT d’Arbeloff Lab)
disclosure: Rhee S, Yang B-H, Asada HH. ‘Artifact-resistant power-efficient design of finger-ring plethysmographic sensors.’ IEEE Transactions on Biomedical Engineering 2001;48(7):795-805 (and Asada HH, Shaltis P, Reisner A, Rhee S, Hutchinson RC. ‘Mobile monitoring with wearable photoplethysmographic biosensors.’ IEEE Engineering in Medicine and Biology Magazine 2003;22(3):28-40).
ip status: patented
sensors: sensor-ppg, sensor-accelerometer
algorithms: algo-hr, algo-spo2-estimation
prior art notes: Discloses a finger-ring-form-factor wearable PPG sensor with motion-artifact-resistant optical/mechanical design, low-power operation, on-body processing, and wireless telemetry of heart rate and SpO2 for ambulatory monitoring — i.e. the smart-ring physiological monitor, ~14 years before the commercial smart-ring wave. Directly anticipates ring-form claims combining ‘a ring body’, ‘a PPG emitter/detector at the inner ring surface’, ‘motion-artifact compensation’, and ‘wireless transmission of derived vitals’. Anchor for the ring × PPG cross-cut; [[oura-ring-gen1-2015]] and similar products descend from it.

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.

Continua Health Alliance — Design Guidelines (first edition, 2007) (2007)

id: continua-design-guidelines-2007
corpus: standards
form factor: other
creator: Continua Health Alliance
disclosure: Continua Health Alliance (later Personal Connected Health Alliance). ‘Continua Design Guidelines’ (first edition published 2007; subsequently maintained, ITU-T H.810 series). Specifies end-to-end interoperability for personal connected health devices, profiling IEEE 11073, Bluetooth, USB, ZigBee, HL7/IHE.
ip status: standards
sensors: sensor-ppg, sensor-ecg, sensor-glucose-cgm, sensor-accelerometer
algorithms: algo-hr, algo-step-count, algo-glucose-cgm-readout
prior art notes: Publicly-published end-to-end interoperability framework for personal connected health devices — defining how a body-worn sensor (weight scale, blood-pressure cuff, glucose meter, pulse oximeter, activity monitor, ECG, etc.) connects to an application hub and onward to health-record systems, profiling the underlying transport and data standards. Prior art for connected-wearable-system claims reciting the architecture, the device-to-hub-to-record data flow, or the standard profiles assembled here, public from 2007.

Allen (2007) — ‘Photoplethysmography and its application in clinical physiological measurement’ (2007-02-20)

id: allen-2007-ppg-review
corpus: academic
form factor: other
creator: John Allen (Freeman Hospital / Newcastle)
disclosure: Allen J. ‘Photoplethysmography and its application in clinical physiological measurement.’ Physiological Measurement 2007;28(3):R1-R39. doi:10.1088/0967-3334/28/3/R01.
ip status: public-domain
sensors: sensor-ppg
algorithms: algo-hr, algo-hrv, algo-respiratory-rate, algo-spo2-estimation, algo-pwv-bp-estimation
prior art notes: Canonical review collecting the state of PPG measurement and the physiological parameters derivable from a PPG signal as of 2007 — heart rate, HRV, respiratory rate, SpO2, blood-pressure surrogates, arterial-stiffness/aging indices, vasomotor assessment. Relevant to wearable claims that recite ‘deriving [parameter X] from a photoplethysmography signal’ for any X covered here: the derivation was a published, enabled technique by 2007, defeating novelty of the bare derivation and supplying § 103 motivation for the form-factor+PPG+algorithm combinations. The single most-cited anchor for PPG-derived-metric wearable patents.

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.

Bluetooth SIG — Heart Rate Profile / Heart Rate Service (2011) (2011-07-12)

id: bluetooth-sig-heart-rate-profile-2011
corpus: standards
form factor: other
creator: Bluetooth Special Interest Group
disclosure: Bluetooth SIG. ‘Heart Rate Profile’ specification v1.0 and ‘Heart Rate Service’ (GATT service UUID 0x180D, characteristics: Heart Rate Measurement 0x2A37, Body Sensor Location 0x2A38, Heart Rate Control Point 0x2A39), adopted 12 July 2011; available at bluetooth.com/specifications.
ip status: standards
sensors: sensor-ppg, sensor-ecg
algorithms: algo-hr
prior art notes: A publicly-adopted standard defining how a body-worn heart-rate sensor advertises, structures, and transmits heart-rate measurements (including energy expended and RR-interval data) over Bluetooth Low Energy to a collector, with a defined sensor-location enumeration including wrist, finger, ear, chest, foot, hand. Prior art for wearable-HR claims reciting ‘a BLE-advertised heart-rate measurement characteristic’, ‘transmission of RR intervals from a body-worn sensor’, or a ‘body sensor location’ field — these were standardized and public from 2011. Relevant to PPG and ECG HR wearables alike.

ISO 80601-2-61 — particular requirements for basic safety and essential performance of pulse oximeter equipment (2011/2017) (2011-08-15)

id: iso-80601-2-61-pulse-oximeter-equipment-2011
corpus: standards
form factor: other
creator: ISO/IEC (TC 121/SC 3 and IEC SC 62D)
disclosure: ISO 80601-2-61:2011 (revised 2017). ‘Medical electrical equipment — Part 2-61: Particular requirements for basic safety and essential performance of pulse oximeter equipment.’ ISO, 2011.
ip status: standards
sensors: sensor-spo2, sensor-ppg, sensor-multi-wavelength-ppg
algorithms: algo-spo2-estimation
prior art notes: Publicly-adopted standard defining pulse oximeter equipment (a device estimating SpO2 and pulse rate from light at two or more wavelengths through perfused tissue) and the accuracy/validation requirements for it. Prior art for wearable-SpO2 claims to the extent they recite the multi-wavelength pulsatile method or the SpO2-and-pulse-rate output described here; the equipment definition and method have been a published standard since 2011 (building on the [[aoyagi-1974-two-wavelength-pulse-oximetry]] principle).

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.

The Circle — ‘SeeChange’ wearable cameras and employee health wristbands (2013-10-08)

id: the-circle-seechange-and-health-wristbands
corpus: fictional
form factor: bracelet
creator: Dave Eggers
disclosure: Eggers, Dave. The Circle. Alfred A. Knopf, 2013 (film adaptation 2017); ‘SeeChange’ miniature wearable/mountable cameras streaming continuously, and employee wristbands (worn in pairs on each wrist) that continuously monitor heart rate, activity, sleep, and other physiological data and upload it to the company.
ip status: fictional
sensors: sensor-ppg, sensor-accelerometer, sensor-camera-rgb
algorithms: algo-hr, algo-step-count, algo-sleep-staging
prior art notes: Discloses (a) continuously-worn wristbands with PPG and motion sensing that stream heart rate, activity, and sleep data to an employer, and (b) tiny body-wearable always-streaming cameras. Relevant to workplace-wellness wearable claims combining ‘a wrist-worn PPG/motion sensor’, ‘continuous physiological streaming to a remote/employer system’, and to body-worn-camera streaming claims. § 103 motivation that the employer-monitored wrist wearable and the always-streaming wearable camera were articulated objectives by 2013.

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.

Microsoft Band (2014) — ten-sensor wristband (optical HR, GPS, GSR, UV, skin temp, barometer, ambient light, capacitive, microphone, IMU) (2014-10-30)

id: microsoft-band-2014
corpus: private
form factor: watch
creator: Microsoft Corp.
disclosure: Microsoft Corp. ‘Microsoft Band’, released 30 October 2014 — a wristband integrating ten sensors: an optical (PPG) heart-rate sensor, a 3-axis accelerometer/gyroscope, GPS, an ambient-light sensor, a skin-temperature sensor, a UV sensor, a capacitive (wear-detection) sensor, a galvanic-skin-response sensor, a microphone, and a barometer (added in Band 2).
ip status: patented
sensors: sensor-ppg, sensor-accelerometer, sensor-gyroscope, sensor-skin-temperature, sensor-uv, sensor-gsr, sensor-barometer, sensor-photodiode-ambient, sensor-microphone-air
algorithms: algo-hr, algo-step-count, algo-calorie-estimation, algo-sleep-staging, algo-stress-index, algo-uv-dose-tracking
prior art notes: Discloses a single wristband integrating an unusually broad sensor suite — reflectance-PPG HR, IMU, GPS, skin temperature, UV exposure, galvanic skin response (electrodermal activity), barometer, ambient light, capacitive wear-detection, and a microphone — feeding HR, activity, sleep, UV dose, and stress-index estimations. Prior art for multi-sensor-wristband claims reciting combinations of these sensors (notably wrist GSR/EDA + PPG + skin temperature for stress) from October 2014. Product-side anchor for the multi-sensor wristband cross-cut.

WHOOP Strap (2015) — display-less wrist/bicep PPG band for continuous HR/HRV, sleep and recovery (2015)

id: whoop-strap-2015
corpus: private
form factor: bracelet
creator: WHOOP, Inc. (Will Ahmed)
disclosure: WHOOP, Inc. ‘WHOOP Strap’, launched 2015 — a screenless band worn on the wrist or upper arm with photoplethysmography, a 3-axis accelerometer, and skin-temperature sensing, providing continuous heart rate, heart-rate variability, respiratory rate, sleep staging, and a derived ‘recovery’ score, with no on-device display.
ip status: patented
sensors: sensor-ppg, sensor-accelerometer, sensor-skin-temperature
algorithms: algo-hr, algo-hrv, algo-respiratory-rate, algo-sleep-staging, algo-activity-classification
prior art notes: Discloses a display-less band worn on the wrist or upper arm with PPG, accelerometry, and skin-temperature sensing that continuously derives HR, HRV, respiratory rate, and sleep stages and combines them into a daily ‘recovery’ index, with no screen (companion-app readout). Anticipates screenless-band claims and PPG-derived-HRV/recovery-score claims from 2015. Product-side anchor for the bracelet × PPG cross-cut and the HRV cross-cut.

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.

Oura Ring (Gen 1, 2015) — finger-ring PPG, skin-temperature and accelerometer for HRV, sleep and body temperature (2015-08)

id: oura-ring-gen1-2015
corpus: private
form factor: ring
creator: Oura Health Oy
disclosure: Oura Health Oy. ‘Oura Ring’ (1st generation), crowdfunded 2015, shipped 2016 — a titanium finger ring with infrared photoplethysmography, an NTC skin-temperature sensor, and a 3-axis accelerometer, deriving resting heart rate, heart-rate variability, respiratory rate, sleep staging, and body-temperature trend.
ip status: patented
sensors: sensor-ppg, sensor-skin-temperature, sensor-accelerometer
algorithms: algo-hr, algo-hrv, algo-respiratory-rate, algo-sleep-staging
prior art notes: Discloses a finger-ring wearable with infrared PPG, a skin-temperature sensor, and an accelerometer, deriving resting HR, HRV, respiratory rate, sleep stages, and a body-temperature trend, with companion-app readout. A commercial realization, ~12-16 years later, of the MIT ring-sensor concept ([[asada-mit-wearable-ring-sensor-2003]]); to the extent later claims recite ring-form PPG + skin-temperature + HRV/sleep, both Asada 2003 and Oura 2015 are prior art. Product-side anchor for the ring × PPG × HRV and ring × skin-temperature cross-cuts.

Mukkamala et al. (2015) — ‘Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Theory and Practice’ (2015-08)

id: mukkamala-2015-ptt-cuffless-bp-review
corpus: academic
form factor: other
creator: Ramakrishna Mukkamala et al.
disclosure: Mukkamala R, Hahn J-O, Inan OT, Mestha LK, Kim C-S, Töreyin H, Kyal S. ‘Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Theory and Practice.’ IEEE Transactions on Biomedical Engineering 2015;62(8):1879-1901.
ip status: public-domain
sensors: sensor-ecg, sensor-ppg, sensor-cuffless-bp-ptt, sensor-cuffless-bp-tonometry
algorithms: algo-pwv-bp-estimation
prior art notes: Canonical 2015 review of cuffless blood-pressure estimation by pulse transit time / pulse arrival time / pulse wave velocity: the physiological models, the practical sensor configurations (ECG+PPG, dual PPG, ballistocardiogram+PPG), the calibration strategies, and the accuracy limitations. Prior art for cuffless-BP wearable claims reciting any of the configurations or calibration approaches surveyed here — they were collected, modeled, and published by 2015. Combined with watch/ring/patch form-factor disclosures, makes wearable PTT-based BP an obvious combination under [[obviousness-template]].

Heikenfeld et al. (2018) — ‘Wearable sensors: modalities, challenges, and prospects’ (2018-01-16)

id: heikenfeld-2018-wearable-sensors-lab-on-chip-review
corpus: academic
form factor: other
creator: Jason Heikenfeld et al.
disclosure: Heikenfeld J, Jajack A, Rogers J, Gutruf P, Tian L, Pan T, Li R, Khine M, Kim J, Wang J, Kim J. ‘Wearable sensors: modalities, challenges, and prospects.’ Lab on a Chip 2018;18(2):217-248.
ip status: public-domain
sensors: sensor-ppg, sensor-ecg, sensor-eeg, sensor-glucose-cgm, sensor-lactate, sensor-cortisol, sensor-skin-temperature, sensor-bioimpedance
prior art notes: Authoritative 2018 review collecting wearable sensing across modalities — physical (motion, BCG/SCG, mechanoacoustic), electrophysiological (ECG/EMG/EEG), optical (PPG/SpO2, near-IR), thermal, electrochemical (sweat, saliva, tears, interstitial), and stimulation-coupled — across form factors (patch, watch, tattoo, contact lens, garment) and the challenges of body-fluid sampling, calibration, motion-artifact handling, and skin-electronics interfacing. Prior art establishing that the modality/form-factor combinations enumerated here were collected and surveyed by 2018; useful against later claims to those combinations. General anchor.

Pine64 PineTime (2018-2020) — low-cost open-source smartwatch (2018-09)

id: pine64-pinetime-2020
corpus: open
form factor: watch
creator: Pine Store Ltd. (Pine64)
disclosure: Pine64. ‘PineTime’ open-source smartwatch — first announced September 2018, dev-kit shipping early 2020, sealed units (~US$30) shipping from late 2020. Hardware: Nordic nRF52832 (ARM Cortex-M4), heart-rate monitor, 3-axis accelerometer, touchscreen, BLE. Open firmware: ‘InfiniTime’ (C++/FreeRTOS) at github.com/InfiniTimeOrg/InfiniTime; ‘Wasp-OS’ (Python/MicroPython) at github.com/daniel-thompson/wasp-os. Hardware schematics at wiki.pine64.org/wiki/PineTime. https://pine64.com/product/pinetime-smartwatch-sealed/
ip status: open-permissive
sensors: sensor-ppg, sensor-accelerometer
algorithms: algo-hr, algo-step-count
prior art notes: Discloses a low-cost (US$30) wrist-worn smartwatch with PPG-HR sensor, accelerometer, touchscreen, BLE, and fully open-source firmware (InfiniTime in C++/FreeRTOS, or Wasp-OS in Python/MicroPython on the same hardware) and published hardware schematics. Establishes (since 2018-2020) that the basic smartwatch architecture — MCU + PPG + accel + display + BLE + open firmware — is unencumbered open-hardware prior art. Distinct from [[healthypi-move-2026]] in being earlier and simpler; together they establish open-watch prior art across a >5-year span.

FDA De Novo DEN180042 (2018) — photoplethysmograph analysis software for over-the-counter irregular-rhythm (possible-AFib) notification (Apple Watch) (2018-09-11)

id: fda-den180042-irregular-rhythm-notification-2018
corpus: regulatory
form factor: watch
creator: U.S. Food and Drug Administration (CDRH); requester Apple Inc.
disclosure: U.S. FDA, De Novo Classification Request DEN180042 (Apple Inc., ‘Irregular Rhythm Notification Feature’), granted 11 September 2018 — decision summary at accessdata.fda.gov/cdrh_docs/reviews/DEN180042.pdf; established a new FDA device classification for software that analyses pulse-rate data from a consumer wrist-worn photoplethysmography sensor, intermittently and in the background, to identify episodes of irregular heart rhythm suggestive of atrial fibrillation and notify the user, with general/special controls.
ip status: regulatory-filing
sensors: sensor-ppg
algorithms: algo-afib-detection, algo-hr
prior art notes: A public, dated FDA decision describing — and creating the device class for — background PPG-based screening for irregular heart rhythm / possible atrial fibrillation on a consumer wrist wearable, with user notification. Establishes as of 11 September 2018 the public availability of: a wrist-PPG device that intermittently analyses pulse-rate variability to flag possible AFib and notifies the wearer. Prior art for later claims to that combination; the decision summary’s account of the algorithm and the Apple Heart Study validation is citable. Pairs with [[apple-watch-series4-ecg-2018]], [[allen-2007-ppg-review]], and the fictional AR-overlay antecedents are irrelevant here — this is enabling prior art.

Apple Watch Series 4 (2018) — wrist single-lead ECG and PPG-based irregular-rhythm notification (2018-09-12)

id: apple-watch-series4-ecg-2018
corpus: private
form factor: watch
creator: Apple Inc.
disclosure: Apple Inc. ‘Apple Watch Series 4’, announced 12 September 2018 (ECG app and irregular rhythm notification feature enabled later in 2018) — a wristworn device taking a single-lead (Lead I) ECG between a back-crystal electrode and a Digital Crown electrode touched by the opposite hand, with on-device AF/sinus classification, plus a PPG-based irregular-rhythm (possible-AF) notification algorithm. FDA cleared via De Novo (ECG app: DEN180044; irregular rhythm notification: DEN180042).
ip status: patented
sensors: sensor-ecg, sensor-ppg
algorithms: algo-afib-detection, algo-arrhythmia-classification, algo-hr
prior art notes: Discloses a wristworn device that records a single-lead ECG between a watch-back electrode and a crown electrode touched by the contralateral hand, classifies the rhythm (AF vs. sinus) on-device, and separately runs a PPG-based background algorithm flagging possible atrial fibrillation. Anticipates wristworn-ECG and watch-AF-detection claims postdating September 2018; the underlying single-lead ECG and PPG-rhythm-screening techniques are much older ([[einthoven-1903-string-galvanometer-ecg]], [[holter-1961-ambulatory-ecg]], [[allen-2007-ppg-review]], [[ieee-11073-10406-basic-ecg-2011]]). Product-side anchor for the watch × ECG and watch × PPG × AF-detection cross-cuts.

Omron HeartGuide (2019) — wristwatch with an inflatable oscillometric blood-pressure cuff in the band (2019-01-08)

id: omron-heartguide-2019
corpus: private
form factor: watch
creator: Omron Healthcare Co., Ltd.
disclosure: Omron Healthcare. ‘HeartGuide’ (model BP8000-M), announced January 2019, FDA-cleared — a wristwatch whose band contains an inflatable cuff and an oscillometric pressure transducer, taking a clinically-validated brachial-style blood-pressure measurement at the wrist on demand, alongside heart rate, steps, and sleep.
ip status: patented
sensors: sensor-pressure-skin, sensor-accelerometer, sensor-ppg
algorithms: algo-hr, algo-step-count, algo-sleep-staging
prior art notes: Discloses a wristwatch whose strap incorporates an inflatable cuff and pressure transducer, performing an oscillometric blood-pressure measurement at the wrist (occlude-and-release, automatically positioned at heart level by the wearer) in a watch form factor, plus activity and sleep tracking. Distinct from cuffless-PPG approaches: it is a true oscillometric cuff miniaturized into a watch band. Anticipates watch-with-integrated-inflatable-cuff BP claims from 2019. Product-side anchor for the watch × oscillometric-BP cross-cut (vs. the cuffless-PPG variant in [[samsung-galaxy-watch-bp-ecg-2020]] and [[aktiia-bracelet-cuffless-bp-2021]]).

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.

Samsung Galaxy Watch3 / Samsung Health Monitor (2020) — wrist single-lead ECG and optical-PPG cuffless blood pressure (2020-08)

id: samsung-galaxy-watch-bp-ecg-2020
corpus: private
form factor: watch
creator: Samsung Electronics Co., Ltd.
disclosure: Samsung Electronics. ‘Samsung Health Monitor’ app on Galaxy Watch3 / Watch Active2, 2020 — wrist single-lead ECG (between a back-crystal electrode and a side-button electrode touched by the opposite hand, with AF/sinus classification) and a cuffless blood-pressure feature using the optical (PPG) pulse-wave signal calibrated against a periodic conventional cuff reading. (Cleared in Korea 2020; subsequently in other markets.)
ip status: patented
sensors: sensor-ecg, sensor-ppg, sensor-cuffless-bp-ptt
algorithms: algo-afib-detection, algo-arrhythmia-classification, algo-pwv-bp-estimation, algo-hr
prior art notes: Discloses a wristworn device that takes a single-lead ECG with on-device AF classification and, separately, estimates blood pressure from the wrist optical-PPG pulse waveform after calibration against a periodic conventional cuff measurement (a calibrated-cuffless approach). Anticipates wrist-cuffless-BP claims reciting ‘estimating blood pressure from a wrist photoplethysmography signal calibrated by a reference cuff reading’ from 2020 — the underlying PTT/PWV-BP technique is much older ([[geddes-1981-pulse-transit-time-bp]], [[mukkamala-2015-ptt-cuffless-bp-review]]). Product-side anchor for the watch × cuffless-BP cross-cut.

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.

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.

Aktiia bracelet (2021) — optical-PPG-based continuous cuffless blood-pressure monitoring bracelet (2021-01)

id: aktiia-bracelet-cuffless-bp-2021
corpus: private
form factor: bracelet
creator: Aktiia SA
disclosure: Aktiia SA. ‘Aktiia bracelet’ (later ‘Hilo’), CE-marked and launched in Europe January 2021 — a slim wristband with optical photoplethysmography that, after a one-time initialization against a conventional cuff (and periodic re-calibration), estimates systolic and diastolic blood pressure several times a day automatically, day and night, from the wrist PPG pulse waveform.
ip status: patented
sensors: sensor-ppg, sensor-cuffless-bp-ptt, sensor-accelerometer
algorithms: algo-pwv-bp-estimation, algo-hr
prior art notes: Discloses a slim wristband that, after a one-time cuff initialization (and periodic re-calibration), automatically estimates systolic and diastolic blood pressure multiple times per day and night purely from the wrist optical-PPG pulse waveform — i.e. continuous, fully cuffless, calibration-initialized wrist BP monitoring. Anticipates continuous-cuffless-wrist-BP claims from 2021; the PPG-pulse-feature-to-BP mapping rests on the much older PTT/PWV-BP and pulse-contour literature ([[geddes-1981-pulse-transit-time-bp]], [[mukkamala-2015-ptt-cuffless-bp-review]]). Product-side anchor for the bracelet × cuffless-BP cross-cut.

Masimo W1 (2022) — first FDA-cleared continuous wrist medical-grade pulse oximetry watch (2022-05)

id: masimo-w1-2022
corpus: private
form factor: watch
creator: Masimo Corp.
disclosure: Masimo Corp. ‘Masimo W1’ health-tracking watch, announced May 2022 — a wrist-worn device performing continuous medical-grade pulse oximetry (SpO2), pulse rate, perfusion index (PI), pleth variability index (PVi), respiratory rate from the PPG, and HRV, using Masimo’s SET/rainbow signal-extraction algorithms. (FDA cleared as a continuous-monitoring medical device.)
ip status: patented
sensors: sensor-ppg, sensor-spo2, sensor-multi-wavelength-ppg, sensor-accelerometer
algorithms: algo-spo2-estimation, algo-hr, algo-hrv, algo-respiratory-rate
prior art notes: Discloses a wrist-worn device performing continuous medical-grade pulse oximetry — SpO2, PR, perfusion index, PVi, RR-from-PPG, HRV — using established signal-extraction methods, distinguished from consumer spot-check SpO2 by continuous operation and clearance for medical use. Anticipates wrist-continuous-medical-SpO2 claims from 2022; the underlying two-wavelength SpO2 method is much older ([[aoyagi-1974-two-wavelength-pulse-oximetry]], [[mendelson-ochs-1988-reflectance-pulse-oximetry]], [[iso-80601-2-61-pulse-oximeter-equipment-2011]]). Product-side anchor for the watch × continuous-SpO2 cross-cut.

Ultrahuman Ring AIR (2023) — smart ring with metabolic-focus tracking (PPG, skin temperature, IMU) (2023)

id: ultrahuman-ring-air-2023
corpus: private
form factor: ring
creator: Ultrahuman Healthcare Pvt. Ltd.
disclosure: Ultrahuman Healthcare Pvt. Ltd. ‘Ultrahuman Ring AIR’, launched 2023 — a titanium smart ring with infrared photoplethysmography, IR skin-temperature, and a 6-axis IMU, deriving HR, HRV, skin temperature, sleep staging, activity, and metabolic-health framing (paired with the company’s CGM-based metabolism platform).
ip status: patented
sensors: sensor-ppg, sensor-skin-temperature, sensor-accelerometer, sensor-gyroscope
algorithms: algo-hr, algo-hrv, algo-sleep-staging, algo-respiratory-rate
prior art notes: Discloses a smart ring with IR PPG, skin-temperature, and a 6-axis IMU, deriving HR/HRV, sleep, and activity, packaged with a metabolic-health platform (CGM-linked). Product-side reference in the ring × PPG cross-cut alongside [[oura-ring-gen1-2015]] and [[samsung-galaxy-ring-2024]].

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.

CogWatch (HardwareX, 2024) — open-source smartwatch for cognitive-load monitoring (2024)

id: cogwatch-2024-hardwarex
corpus: academic
form factor: watch
creator: (See HardwareX publication for full author list.)
disclosure: ‘CogWatch: An open-source smartwatch platform for cognitive-load monitoring.’ HardwareX 19 (2024). Open-source smartwatch design — full hardware, firmware, and assembly documentation published in the open-hardware-focused journal HardwareX (Elsevier). https://www.hardware-x.com/article/S2468-0672(24)00032-4/fulltext
ip status: public-domain
sensors: sensor-ppg, sensor-gsr, sensor-accelerometer
algorithms: algo-hr, algo-hrv, algo-stress-index, algo-cognitive-workload
prior art notes: Discloses, as open-hardware (HardwareX is the canonical venue for full publication of open-hardware designs), a wrist-worn smartwatch instrumented for cognitive-load monitoring from PPG-derived HRV and EDA/GSR. Prior art for smartwatch-cognitive-load claims combining ‘a wrist-worn device’, ‘PPG and EDA sensors’, and ‘a derived cognitive-load metric’ from 2024.

Samsung Galaxy Ring (2024) — smart ring with PPG, skin temperature and accelerometer for HR/HRV, sleep and cycle tracking (2024-07-10)

id: samsung-galaxy-ring-2024
corpus: private
form factor: ring
creator: Samsung Electronics Co., Ltd.
disclosure: Samsung Electronics. ‘Samsung Galaxy Ring’, announced July 2024 — a finger ring with infrared photoplethysmography, an IR skin-temperature sensor, and a 3-axis accelerometer, deriving heart rate, heart-rate variability, skin temperature, sleep staging, activity, snore detection, and (with cycle-tracking) menstrual-cycle predictions.
ip status: patented
sensors: sensor-ppg, sensor-skin-temperature, sensor-accelerometer
algorithms: algo-hr, algo-hrv, algo-respiratory-rate, algo-sleep-staging, algo-snore-detection, algo-step-count
prior art notes: Discloses a smart ring with infrared PPG, IR skin-temperature, and accelerometer, deriving HR/HRV, sleep, snore detection, activity, and menstrual-cycle prediction — a Samsung entry directly in the wake of [[oura-ring-gen1-2015]] and the [[asada-mit-wearable-ring-sensor-2003]] academic root. Product-side reference in the ring × PPG × HRV cross-cut alongside Oura.

Cross-cut: sensor-ppg