?? Exploring Photoplethysmography (PPG) Sensors

In the PRO versions of Neiry headphones and bands, alongside EEG, there are PPG sensors, gyroscopes, and accelerometers. While many are familiar with gyroscopes and accelerometers, let's delve into the details of PPG.

Photoplethysmography (PPG) is a method of measuring blood volume in vessels using light. It finds wide applications in medical and sports devices like pulse oximeters, fitness bands, and smartwatches.

PPG works by assessing tissue density. A light emitter illuminates the skin, while a photodetector registers the reflected and transmitted light. As the heart contracts, blood volume in the vessels increases, and during relaxation, it decreases. This leads to fluctuations in reflected light intensity, which the PPG sensor detects. By analyzing these fluctuations, we can determine intervals between heartbeats. The PPG signal in Neiry devices is sampled at a frequency of 100 Hz.

PPG allows us to determine not only heart rate but also Heart Rate Variability (HRV).

HRV refers to the natural variation in intervals between consecutive heartbeats (cardiac cycles) of the normal sinus rhythm. It reflects the state of the autonomic nervous system, which regulates heart function. HRV can be assessed through various parameters, such as mean values, standard deviation, spectral analysis, nonlinear methods, and more.

High HRV indicates good adaptability to changing conditions and a lower risk of heart-related issues, while low HRV suggests disrupted heart rate regulation and increased risk of complications. HRV can also be associated with a person's emotional state since emotions influence autonomic nervous system activity. For instance, joy and pleasure elevate HRV, whereas anger, fear, and stress can decrease it.

Thus, PPG provides additional means of measuring a user's condition, complementing EEG where needed or synergizing to yield comprehensive insights. #PPG #BiomedicalSensors #HRV #HealthTech #NeiryDevices