Measuring Particle Positions in Micro Channel with Multifiber Array

This paper proposes position measurement of particles in micro channels fabricated on a polydimethylsiloxane (PDMS) chip using a two-layer plastic optical fiber (POF) array. Particle positions are measured by irradiating the POF array with laser light and measuring the decrease in POF output power posed by the presence of the particle. Our proposed sensor provides three dimensional measurements in the micro channel along the directions of the length, depth and the width. We demonstrate that plural particles of different diameters can be measured with our proposed sensor in which two layers of POF are vertically aligned or shifted along the flow direction. The effects of optical misalignment of POF array with respect to the measurement are theoretically and experimentally evaluated.