Abstract

A Microfluidic Serial Cytometer to Estimate Per-Cell Uncertainty and Single Object Kinetic Measurements

Gregory Cooksey, Project Leader, National Institute of Standards and Technology

NIST has developed a serial microfluidic cytometer that repeats the interrogation of objects at multiple points along a flow path, which enables direct assessment of uncertainty in cytometry measurements (DiSalvo et al., Lab Chip 2022). We have achieved per-particle measurement variation below 2 % at throughputs above 100 s^-1 and detection limits and dynamic range comparable to conventional cytometers. This presentation will introduce various measurement capabilities novel to our serial cytometry, including 1) uncertainty quantification, 2) signals analysis that permit estimation of velocity, size, and shape of samples, including elastically deformable particles and mitotic cells, and 3) tracking dynamics of individual objects over time. Utilizing microdroplets, we demonstrated temporal tracking of an enzymatic reaction on a per-droplet basis in real time.  An upstream fluidic mixing system is also used to create known concentrations and dilutions of fluorophores in droplets, which permits direct calibration of measured fluorescence intensity to fluorophores in solution.