Influence of contact forces on wrist photoplethysmography - Prestudy for a wearable patient monitor
Influence of contact forces on wrist photoplethysmography - Prestudy for a wearable patient monitor
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DOI：
10.1515/bmt.2004.005
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发表时间：
2004-01-01
期刊：
影响因子：
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通讯作者：
Gallasch, E
中科院分区：
文献类型：
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作者：
Rafolt, D;Gallasch, E
实际设置表明，在光电传感器上的温和的手动压力足以提高动脉脉搏的可检测性，但施加的压力的变化也可能产生信号伪影。为了研究这些影响，对放置在桡动脉上的光电传感器施加逐步增加的贴靠力（0.5至4 N）。此外，通过引入弹性距离环，研究了传感器和皮肤表面之间的光耦合的影响。分析来自所记录的光电体积描记图的AC和DC分量。AC分量（由于动脉搏动的吸收）随施加的压力而增加;在较低的力（0.5至3 N）下，引入环增强了这种效果。DC分量的特性（来自非脉动组织的反向散射）取决于光耦合：在没有环的情况下，DC分量随力逐步增加（斜率为0.035 V/N），但在环就位的情况下，该分量减小（斜率为-0.075 V/N）。由于脉冲信号对伪影的灵敏度与DC分量的斜率有关，因此可以通过使斜率小来使这种伪影最小化。讨论了利用这些结果来改善脉搏检测并减少可穿戴手腕设备中的运动伪影。
The practical setting shows that gentle manual pressure on a photosensor suffices to improve the detectability of arterial pulses, but changes in the pressure applied may also produce signal artefacts. To study these effects, stepwise increasing contact forces (0.5 to 4 N) were applied to a photosensor placed over the radial artery. Additionally, the influence of optical coupling between sensor and skin surface was examined by introducing an elastic distance ring. The AC and DC components from the recorded photoplethysmogram were analysed. The AC component (absorption due to arterial pulsation) increased with the pressure applied; at lower forces (0.5 to 3 N) an introduction of the ring enhanced this effect. The characteristic of the DC component (backscattering from non-pulsating tissues) depends on optical coupling: without the ring the DC component increased stepwise with force (slope 0.035 V/N), but with the ring in place this component decreased (slope -0.075 V/N). Since the sensitivity of the pulse signal to artifacts is related to the slope of the DC component, such artefacts can be minimized by making the slope small. The utilization of these results to improve pulse detection and reduce motion artefacts in a wearable wrist device is discussed.