Intersection cross-cut: sensor-ppg ∩ algo-stress-index

Axes: sensors × algorithms

3 corpus entries disclose both tags.

Earliest disclosure: 1996-03

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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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.

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.

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.