Annu Int Conf IEEE Eng Med Biol Soc. 2022 Jul;2022:3146-3149. doi: 10.1109/EMBC48229.2022.9871985.
PhotoPlethysmoGraphy (PPG) is ubiquitously employed in wearable devices for health monitoring. Photodiode signal inversion is observed in rare occasions, most of the time when the sensor is pressed against the skin. We report in this article such observations made at the right common carotid artery site. Indeed we have systematically observed a photodiode signal inversion when the PPG sensor is placed where the pulse is the best felt at the carotid. In addition to be inverted, the pulse is steeper during the systolic phase. Such inversion has implications in terms of pulse arrival time (PAT) measurements In our experiments, this causes a difference of 20 ms in the carotid PAT when measured at the absolute maximum slope. The mechanical and optical properties of tissues must be better accounted to explain the PPG signal morphology. Clinical Relevance- Understanding the role of mechanical tissue properties seems relevant in order to obtain more reproducible results in PPG signal analysis.
光电容积脉搏波描记法（PPG）广泛应用于可穿戴设备的健康监测中。光电二极管信号反转在罕见情况下会被观察到，大多数时候是在传感器紧贴皮肤时发生。我们在本文中报告了在右颈总动脉部位观察到的这种现象。实际上，当 PPG 传感器放置在颈动脉处脉搏最容易感觉到的位置时，我们已经系统地观察到光电二极管信号的反转。除了反转之外，在收缩期期间脉搏更为陡峭。这种反转会对脉搏到达时间（PAT）测量产生影响。在我们的实验中，当在绝对最大斜率处测量时，这会导致颈动脉 PAT 出现 20 毫秒的差异。组织的力学和光学特性必须得到更好的解释，以解释 PPG 信号形态。临床意义——为了在 PPG 信号分析中获得更具可重复性的结果，了解力学组织特性的作用似乎很重要。
