Intersection cross-cut: other ∩ sensor-multi-wavelength-ppg
Axes: form_factor × sensors
3 corpus entries disclose both tags.
Earliest disclosure: 1974
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.
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]].
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.
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).