A microfluidic scanning flow cytometer with superior signal-to-noise-ratio for label-free characterization of small particles

¹ Center for Life Nano- & Neuro-Science, Italian Institute of Technology, Rome, Italy
² Sapienza University of Rome, Rome, Italy
³ Institute of Nanotechnology of the National Research Council of Italy, CNR-NANOTEC, Rome Unit, Piazzale A. Moro 5, I-00185, Rome, Italy

^* Corresponding author: riccardo.reale@iit.it

Published online: 31 October 2024

Abstract

Single-cell analysis without immune-specific labelling is essential across research fields, but conventional flow cytometers (FCMs) struggle with label-free analysis. We introduce a novel microfluidic scanning flow cytometer (μSFC) designed for label-free analysis within a simple microfluidic chip. Our system outperforms traditional FCMs for label-free analysis but its signal-to-noise ratio (SNR) limits the minimum detectable size. We present three modifications to enhance SNR and improve the smallest detectable particle size: additional neutral optical density filtering, a lower noise-equivalent-power photoreceiver, and laser spot size reduction. These improvements enable reliable characterization of particles as small as 3 μm. Experimental results validate the correlation between angular profile oscillations and particle size. While reliable detection down to 1 μm is achieved, further refinement is needed. The simplicity and low setup of the μSFC make it promising for integration into multi-parametric single-cell analysis systems, facilitating comprehensive cellular characterization for diagnostic and point-of-care applications.