Analysis Of PPG Signal Correlation With Cardiac and Respiratory Signals In Humans Using Spectral Analysis Techniques

Abstract

Non-invasive diagnostics is a growing discipline, and ophthalmic devices that usage photons as detecting essentials are becoming progressively significant and pertinent in this context. The reason for this is that they may be used for research purposes with little to no financial outlay, thanks to their simple structure, ease of use, and low cost in compared to equipment like EEG, MRI, and FMRI. Photoplethysmography (PPG) sensors, which are able to measure blood volumetric changes in the subcutaneous vessels, are used in the present work with sensitive temperature sensors to track respiratory activity. A peak at around 0.12 Hz is also visible in a detailed analysis of the PPG signal's frequency spectrum (fb). Low frequency rhythms, also known as the relaxation rhythm, are said to be accentuated/made more prominent at 0.13Hz (fl) in combination with the respirational ultimate throughout deep inhalation. FFT graphs signal power over the whole frequency spectrum. As the PPG FFT comprises many peaks, Power spectral density has been employed to avoid misperception. Normally, the cardiac uttermost is the utmost pronounced PPG top. Breathing frequency peaks are weaker. Other than these two peaks, a peak of 0.14 or less may be identified, depending on the subject's mental and physical health.