Intersection cross-cut: `other` ∩ `sensor-ppg`

Axes: form_factor × sensors

15 corpus entries disclose both tags.

Earliest disclosure: 1937

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.

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.

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.

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.

Intersection cross-cut: other ∩ sensor-ppg