A Novel Pulse Measurement System by Using Laser Triangulation and a CMOS Image Sensor

Abstract

This paper presents a novel, non-invasive, non-contact system to measure pulsewaveforms of artery via applying laser triangulation method to detect skin surfacevibration. The proposed arterial pulsation measurement (APM) system chiefly consists of alaser diode and a low cost complementary metal-oxide semiconductor (CMOS) imagesensor. Laser triangulation and centroid method are combined with the Fast FourierTransform (FFT) in this study. The shape and frequency of the arterial pulsation can bedetected rapidly by using our APM system. The relative variation of the pulse at differentmeasurement points near wrist joint is used as a prognostic guide in traditional Chinesemedicine (TCM). An extensive series of experiments was conducted to evaluate theperformance of the designed APM system. From experimental results, the pulse amplitudeand frequency at the Chun point (related to the small intestine) of left hand showed anobvious increase after having food. In these cases, the peak to peak amplitudes and thefrequencies of arterial pulsations range from 38 to 48 μm and from 1.27 to 1.35 Hz,respectively. The height of arterial pulsations on the area near wrist joint can be estimatedwith a resolution of better than 4 μm. This research demonstrates that applying a CMOSimage sensor in designing a non-contact, portable, easy-to-use, low cost pulse measurementsystem is feasible. Also, the designed APM system is well suited for evaluating and pre-diagnosing the health of a human being in TCM clinical practice.

Keywords

• Arterial pulsation
• Centroid method
• CMOS image sensor
• Laser triangulation
• Pulse frequency.