Characterization of subcellular morphology of single yeast cells using high frequency microfluidic impedance cytometer

Abstract

Single-cell impedance cytometry is an electrical analysis method, which has been used to count and discriminate cells on the basis of their dielectric properties. The method has several advantages, such as being label free and requiring minimal sample preparation. So far, however, it has been limited to measuring cell properties that are visible at low frequencies, such as size and membrane capacitance. We demonstrate a microfluidic single cell impedance cytometer capable of dielectric characterization of single cells at frequencies up to 500 MHz. This device features a more than ten-fold increased frequency range compared to other devices and enables the study of both low and high frequency dielectric properties in parallel. The increased frequency range potentially allows for characterization of subcellular features in addition to the properties that are visible at lower frequencies. The capabilities of the cytometer are demonstrated by discriminating wild-type yeast from a mutant, which differs in size and distribution of vacuoles in the intracellular fluid. This discrimination is based on the differences in dielectric properties at frequencies around 250 MHz. The results are compared to a 3D finite-element model of the microfluidic channel accommodating either a wild-type or a mutant yeast cell. The model is used to derive quantitative values to characterize the dielectric properties of the cells.

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

“…below the range of the -dispersion) is similar to that of an insulating particle (e.g. Schade-Kampmann et al (2008), Haandbaek et al (2014)). The method is also promising for nonspherical particles or cells because, although the latter yield impedance signals depending on their orientation (Jones 1995;Fernandez et al 2017), the transit times and the relative prominence are not significantly affected by particle orientation.…”

Analyzing Single Giant Unilamellar Vesicles With a Slotline-Based RF Nanometer Sensor

“…However, most DS efforts, as well as electromechanical methods that also exploit cell electrical properties (e.g., electrophoresis (DEP) and electrorotation [8], [9]), operate at relatively low frequencies. High frequencies are expected to be necessary to probe cell interiors [10], [11] while broad frequency coverage is essential to uncover cell characteristics.…”

Integrating impedance-based growth-rate monitoring into a microfluidic cell culture platform for live-cell microscopy

“…The convolution of these effects currently limits the ability of the system in distinguishing between single or budded cells, and small cell clusters. Other studies have shown that optimized geometries and setups, featuring multiple facing and focusing electrodes, provide the capability to distinguish between different cell clusters 26 or to analyze intra-cellular features 41 . However, integration of complex sensing structures, such as sandwich structures 41 or electrode posts perpendicular to substrate plane 42 , into the current setup would increase device complexity and compromise ease of cell loading, culturing, and imaging.…”

“…Other studies have shown that optimized geometries and setups, featuring multiple facing and focusing electrodes, provide the capability to distinguish between different cell clusters 26 or to analyze intra-cellular features 41 . However, integration of complex sensing structures, such as sandwich structures 41 or electrode posts perpendicular to substrate plane 42 , into the current setup would increase device complexity and compromise ease of cell loading, culturing, and imaging. The current setup meets the requirements for measuring cell growth rates and changes in those, as the passage of clustered cells over the electrodes happened very rarely, as has been confirmed with microscopy observations.…”