Assessment on Self-mixing Laser Interferometry for Blood flow Measurement over Skin Surface

Abstract

We study self-mixing laser diode (SM-LD) as a low-cost and compact optical sensor for non-invasive blood flow measurement and profiling over the skin surface. By making in-vivo and in-vitro measurements, we compare the SM-LD based sensor with the commercially available flowmeters to assess the accuracy and feasibility of SM-LD sensors for such applications. For the SM-LD based sensor, we apply two different signal processing methods (i) counting the intensity fluctuations of the signal from the SM-LD to obtain a frequency value, and (ii) the autocorrelation of the signal. In-vitro measurements show good agreement with the commercially available flowmeters. In-vivo measurements performed on test subjects revealed that autocorrelation technique shows much better results than the counting technique in blood flow profiling and SM-LD based sensor suffers from errors caused by external artifacts during measurements.

Self-mixing microprobe for monitoring microvascular perfusion in rat brain

“…It is necessary to understand how the system responds to velocity and concentration of scatterers in order to use it in perfusion measurements. The variations of the back-coupled light intensity and its relation with the perfusion as well as the speckle statistical properties obtained from microcirculation blood flow must be understood [20,21]. This is crucial to compare selfmixing sensors with the commercial sensors available.…”