A Microfluidic Platform for Characterizing Single-Cell Intrinsic Bioelectrical Properties With Large Sample Size

Abstract

As the golden instrument of blood-cell phenotyping, hematology analyzers still cannot quantify intrinsic bioelectrical parameters of single cells due to limitations in sensitive structures and models. In this article, a microfluidic impedance platform composed of multiple paralleled double T-type constriction microchannels was developed, where raw impedance of traveling cells can be converted into intrinsic bioelectrical parameters of specific membrane capacitance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}_{\textit {sm}}$ </tex-math></inline-formula> , cytoplasmic conductivity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma _{\textit {cy}}$ </tex-math></inline-formula> , and cell diameter <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${D}_{c}$ </tex-math></inline-formula> leveraging the newly developed bioelectrical model. In order to solve the problem of channel blockage, pathways for impedance measurement and cellular passing through were decoupled, and thus the microfluidic platform was capable of characterizing 1906 ± 909 K562 cells/sample ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${n}_{sample} =$ </tex-math></inline-formula> ~50) and 2010 ± 1218 HL-60 cells/sample ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${n}_{sample} =$ </tex-math></inline-formula> ~30), effectively meeting the requirements of hematology analyzers (~1000 cells/sample). Based on this microfluidic platform: 1) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}_{\textit {sm}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma _{\textit {cy}}$ </tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${D}_{c}$ </tex-math></inline-formula> from ~100000 K562 and HL-60 cells were quantified, producing a high successful rate of ~100% in classifying K562 versus HL-60 cells and 2) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}_{\textit {sm}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma _{\textit {cy}}$ </tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${D}_{c}$ </tex-math></inline-formula> from ~1000 cells of granulocytes, lymphocytes, and monocytes were quantified, producing a high successful rate of ~80% in classifying these three types. In conclusion, the presented microfluidic platform has the potential to be used as an indispensable sensing unit in hematology analyzers in the future.