Lens-integrated real-time simultaneous measurement of particle size and refractive index inspired by vision correction technology

Abstract

In environmental and medical fields, particle size and refractive index are often need to be measured simultaneously. Current methods typically separate the excitation source and detector, increasing system complexity and optical loss. Inspired by vision correction techniques, this study introduces an innovative lens-integrated microfluidic platform. We utilized a tapered microcapillary combined with single-fiber optical tweezers to achieve real-time simultaneous measurement of the size and refractive index of yeast, silica, polymethyl methacrylate (PMMA) and polystyrene (PS). The curved outer wall of the tapered microcapillary acts like a meniscus lens, working with the spherical lens formed by the particles. This reduces spherical aberration, allowing precise adjustment of the light path and simplifying the device structure so that a single fiber serves as both the excitation source and detector. Experimental results show that for 0.1w.t.% particle concentration, real-time detection accurately reflects particle size and refractive index, with a maximum standard deviation of 0.34 %.