The Parameter Investigation of Electrical Impedance Cytometry for Droplet Measurement

Electrical impedance cytometry (EIC) serves as a crucial tool within the realm of microfluidics, providing a label-free, precise, and high-throughput means for assessing cells and particles. In this study, we explore the optimal experimental parameters in terms of EIC for droplet measurement. Initially, a microfluidic platform incorporating an EIC module is established. Within this setup, droplets comprising phosphate-buffered saline (PBS) solution are generated. They flow through the microchannel positioned above the EIC region for signal outputs. The relationships between droplet length, electrode length, and droplet interval distance are systematically investigated. Optimal conditions for achieving complete signal waveforms are identified, wherein the electrode length exceeds the droplet length but falls short of the droplet interval distance. This is corroborated by both simulation and experimental results. Furthermore, droplet geometry proves to influence the shape of the generated signal waveform. Finally, the microfluidic system demonstrates accurate measurements of droplet lengths spanning 95, 230, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$350~\mu $ </tex-math></inline-formula>m at total flow rates of 24, 30, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$40~\mu $ </tex-math></inline-formula>L/min, respectively. This study is anticipated to elucidate the underlying principles guiding ECI design and further contribute to advancements in the field of droplet microfluidics.