Optical Feedback Interferometry Based Microfluidic Sensing: Impact of Multi-Parameters on Doppler Spectral Properties

Abstract

As a compact and simple sensing technique, optical feedback interferometry (OFI) can be a promising flowmetry method in various microfluidic applications. In this paper, OFI-based flowmetry sensor performance in a microscale flow scheme is studied theoretically and experimentally. An innovating model and different numerical methods are investigated, where the scattering light angle distribution is involved to predict the Doppler frequency distribution. For the first time, our model describes the influences of multiple OFI sensor system characteristics, such as flowing particle size, concentration, channel interface reflectivity and channel dimension, on the OFI signal spectral performances. In particular, a significant OFI signal level enhancement was achieved by deposing a high reflectivity gold layer on the rear channel interface due to the increased forward scattered light reflection. The consistent experimental validation associated with the simulations verifies this numerical simulation method’s reliability. The numerical methods presented here provide a new tool to design novel microfluidic reactors and sensors.

Phase-unwrapping algorithm combined with wavelet transform and Hilbert transform in self-mixing interference for individual microscale particle detection

“…According to the above-mentioned section, the particle-induced SMI signal is in a temporally intermittent form during the particle passage. Moreover, the signal burst normally is affected by white Gaussian noise, impulsive noise, and DC pedestal [34,35] . The signal burst of each particle is ambiguous and merged in the noises, so an efficient method of burst identification and denoising is demanded.…”

Self-Mixing Interferometry-Based Micro Flow Cytometry System for Label-Free Cells Classification

“…When the cell crosses the laser emission area with a constant velocity V, a Doppler frequency shift f D is induced. The absolute value of the frequency shift can be expressed in the following form [33]:…”

“…Another point of interest from Figure 5 is that for 5 μm particles provided more than 2500 mV signal amplitude is observed which is higher than the one of 2 μm particles. This aspect can be explained by the particle size also determining the particle scattering cross-section, so larger particle scatters more light feeding back into the laser cavity and resulting in a bigger modulation index m value and higher SMI signal amplitude level [33]. The fringe counting method's feasibility for PS spherical particle sizing has been proved [31].…”

Micro Particle Sizing Using Hilbert Transform Time Domain Signal Analysis Method in Self-Mixing Interferometry

“…As a low-cost, self-aligned, nonintrusive, compact, and reliable sensing approach, self-mixing interferometry (SMI) technology-based microfluidic sensing has gained much attention during the last several decades [1][2][3][4][5]. In such schemes, the laser output amplitude and frequency are modulated when a small fraction of the laser emission is scattered backward by a small particle in the microchannel coupled into the laser cavity.…”