Multispectral PPG
What is multispectral PPG?
Multispectral PPG uses more than one wavelength to observe tissue and pulse behavior from several optical perspectives. A green-only device can estimate pulse well under good conditions, but it has limited ability to distinguish blood-volume change from skin tone, contact pressure, motion, temperature, and deeper tissue effects.
Why one wavelength is not enough
Single-channel PPG can be useful, but it is fragile. The same amplitude change can come from physiology, strap pressure, motion, ambient leakage, temperature, or skin contact. Multiple wavelengths do not magically solve the problem, but they create a richer signal space for separating causes.
SciFold uses Green, Red, IR940, and IR1050 because each channel emphasizes a different part of the optical interaction with tissue. The important claim is not that every wavelength directly measures a clinical variable. The realistic claim is that the channel set improves context for trend detection.
Channel roles
Green is useful for strong superficial pulse detection and HR/HRV foundations. Red and IR940 provide oxygenation-related optical contrast and deeper vascular context. IR1050 adds a near-infrared channel beyond standard wearable PPG, useful for baseline-relative trend features when paired with the other channels.
The value is in the fusion: channel ratios, waveform timing, pulse shape, amplitude stability, spectral energy, and confidence metrics can be evaluated together instead of treating each channel as an independent measurement.
Wellness boundary
SciFold should be explicit: multispectral PPG is not a shortcut to diagnostic blood pressure or glucose. The website should keep saying baseline-relative wellness trends, confidence-gated outputs, and non-diagnostic interpretation. That positioning is more credible than overclaiming.
FAQ
Can multispectral PPG measure glucose directly?
No. Standard wrist PPG should not be presented as direct glucose measurement. SciFold focuses on wellness trend interpretation.
Why use four wavelengths?
Because different wavelengths respond differently to superficial pulse, deeper optical paths, oxygenation-related contrast, and tissue/context effects.