An impedance-based flow microcytometer for single cell morphology discrimination

Abstract

Cell shape is a fundamental biological feature, providing specific information about physiological or pathological cellular conditions. Most of the state-of-the-art microfluidic cytometers, however, only allow simple cell analysis, including viability studies, cell counting and sorting. In this work, we present a non-invasive, label-free device capable of single cell morphology discrimination in continuous flow. The device is based on the principle of liquid electrodes, fabricated in a cross configuration around a sensing zone. This arrangement allows measurement of cell impedance along orthogonal orientations and extraction of an index describing cell shape anisotropy. By adding prior to the sensing volume a series of lateral liquid electrodes, the particle stream was focused toward the channel midline and each cell was oriented in a specific direction before shape sensing. We demonstrate the proof of concept by performing spherical and elongated particle discrimination. As an application, we show that the shape changes experienced during cell division can be monitored and characterized. In particular, budding yeasts at different stages of the mitotic cycle were identified by extracting their anisotropy index.

Electrical measurement of cross-sectional position of particles flowing through a microchannel

“…As an example, detecting cross-sectional position of flowing particles is essential in the investigation of self-ordering mechanisms (Gao et al 2017), inertial particle focusing (Di Carlo 2009) or active particle focusing [e.g. dielectrophoretic (Shaker et al 2014) and acustophoretic (Muller et al 2013)], which have applications in single-cell analysis and sorting (Wyatt Shields IV et al 2015). In fact, under specific force fields, position can directly indicate the property of target cells (Wang et al 2017).…”

High accuracy particle analysis using sheathless microfluidic impedance cytometry

“…A voltage is applied at several different frequencies and the change in current is analysed to determine the cell dielectric properties. Microfluidic impedance cytometry has been used to analyse micro-organisms [5][6][7] , erythrocytes 8,9 , leukocytes 10,11 , platelets 12,13 , and animal and human cell lines [14][15][16] . Low frequency (e.g.…”

A Simple and Robust Event-Detection Algorithm for Single-Cell Impedance Cytometry

“…Absolute measurement schemes, instead of differential ones, are sometimes adopted in microfluidic impedance cytometry (e.g., [8]), generally yielding even-symmetric event patterns. The proposed algorithm may be adapted to those situations by replacing the odd-symmetric template h with a rectangular window, and exchanging the role of the even and odd parts in the quality check procedure.…”

“…At high frequencies (above some MHz), the membrane is minimally polarized, and measurements give information about cytoplasm conductivity and permittivity [1]. Recent work using microfabricated systems has demonstrated the capability to analyze micro-organisms [7], [8], erythrocytes [9], [10], leukocytes [11], platelets [12], and animal and human cell lines [13], [14], [15], [16]. However, microfluidic impedance cytometry has not yet reached full maturity, since sensitivity, specificity and throughput still need to be improved to cope with the most demanding applications.…”