Signal Savvy: Age & Skin Tone

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Age:45 SNR increases by +0.12 dB per year (Table 5)

Skin Tone (Fitzpatrick):3 SNR decreases by -0.52 dB per level (Table 5)

LED Intensity:50% Compensates for light absorption by skin

How to Use

Your goal is to achieve the highest Signal Quality (SNR). Use the sliders to adjust the participant's characteristics (age and skin tone) and the sensor's settings (LED intensity). Observe how the PPG waveform and SNR score change in real-time. The LED intensity slider can help compensate for challenges like darker skin tones, while age adjustments reflect the natural changes in signal quality over time. The audio feedback provides immediate cues on significant changes in signal quality.

Scientific Basis

This simulation is based on the quantitative findings from Charlton et al. (2025). The Signal-to-Noise Ratio (SNR) is calculated using coefficients derived from statistical models in the study (Table 5 and Figure 7). The key factors influencing SNR are:

Age: SNR increases by +0.12 dB per year, reflecting improved signal clarity with age.
Skin Tone: SNR decreases by -0.52 dB for each level on the Fitzpatrick scale, highlighting the impact of melanin on light absorption.
LED Intensity: Higher LED intensity compensates for light absorption, with a maximum boost of +5.0 dB.

The simulation also incorporates random variance to mimic real-world signal fluctuations and adjusts the PPG waveform's noise, wander, and amplitude based on the calculated SNR.

Future Directions

This web application serves as an educational tool to demonstrate the factors affecting PPG signal quality. Future enhancements could include:

Integration of additional physiological parameters, such as heart rate variability and motion artifacts.
Support for real-time data input from wearable devices for personalized simulations.
Expanded scientific models incorporating diverse populations and environmental conditions.
Interactive tutorials and case studies to deepen user understanding of PPG technology.

References

Charlton, P. H., Marozas, V., Mejía-Mejía, E., Kyriacou, P. A., & Mant, J. (2025). Determinants of photoplethysmography signal quality at the wrist. PLOS Digital Health, 4(6), e0000585. https://doi.org/10.1371/journal.pdig.0000585