Handheld microflow cytometer based on a motorized smart pipette, a microfluidic cell concentrator, and a miniaturized fluorescence microscope

Abstract

Miniaturizing flow cytometry requires a comprehensive approach to redesigning the conventional fluidic and optical systems to have a small footprint and simple usage and to enable rapid cell analysis. Micro fluidic methods have addressed some challenges in limiting the realization of micro flow cytometry, but most micro fluidics-based flow cytometry techniques still rely on bulky equipment (e.g., high-precision syringe pumps and bench-top microscopes). Here, we describe a comprehensive approach that achieves high-throughput white blood cell (WBC) counting in a portable and handheld manner, thereby allowing the complete miniaturization of flow cytometry. Our approach integrates three major components: A motorized smart pipette for accurate volume metering and controllable liquid pumping, a micro fluidic cell concentrator for target cell enrichment, and a miniaturized fluorescence microscope for portable flow cytometric analysis. We first validated the capability of each component by precisely metering various fluid samples and controlling flow rates in a range from 219.5 to 840.5 μL/min, achieving high sample-volume reduction via on-chip WBC enrichment, and successfully counting single WBCs flowing through a region of interrogation. We synergistically combined the three major components to create a handheld, integrated micro flow cytometer and operated it with a simple protocol of drawing up a blood sample via pip etting and injecting the sample into the microfluidic concentrator by powering the motorized smart pipette. We then demonstrated the utility of the microflow cytometer as a quality control means for leuk oreduced blood products, quantitatively analyzing residual WBCs (r WBCs) in blood samples present at concentrations as low as 0.1 rWBCs/μL. These portable, controllable, high-throughput, and quantitative micro flow cytometric technologies provide promising ways of miniaturizing flow cytometry.