Dielectric characterization of bioparticles via electrokinetics: The past, present, and the future

Abstract

Electrical properties of biological cells are useful to distinguish cells, either in their homogenous or heterogenous populations. They provide insight into the health, geometry, growth, differentiation, function, and physiological state, including death of any biological cell, i.e., phenotype and genotype of a cell. These properties play an important role in designing various microfluidic chip-based diagnostic tools that utilize electric field gradients for cell movement. Reported studies over several decades have revealed that electrorotation, dielectric spectroscopy, and dielectrophoresis are the most common cell characterization techniques to obtain electrical parameters. However, in each of these characterization techniques, several advancements have been reported especially within the last decade. Details of these advances vary from sophisticated methods like grinding electrode materials and mixing them with polymer composites for use as electrorotation electrodes to simple targeted means like using biological cells itself as electrodes. These advances in technologies are very well discussed in this review. Sequentially, a complete description of the characterized electrical properties targeted to specific bioparticles of interest is presented. The main concepts of dielectrophoresis, electrorotation, and impedance cytometry are given alongside the generated spectra including their analyses for both single and multiple cells. Also, various methods of electrode design, spacing, and fabrication are adequately discussed. The materials used for fabricating the electrodes and their advancement over time with respect to the choice of the materials are also substantially addressed. Finally, with the growing trend observed within this time frame, the future direction of bioparticle characterization could be predicted.

Electrically driven microfluidic platforms for exosome manipulation and characterization

“…Alternatively, the presence of a particle might distort a given electric field in a specific manner, and such distortion can be used for particle characterization purposes, as in the case of electrochemical impedance spectroscopy EIS [28]. In any case, the electric field distribution must be carefully analyzed towards designing fields for tailored performance [29].…”

Utilization of Dielectrophoresis for the Quantification of Rare Earth Elements Adsorbed on Cupriavidus necator

“…necator moved towards the planar electrode thus influencing only the membrane, termed as negative DEP. A crossover frequency ( f co ) is determined (zero DEP force) when the changing DEP force transitions from pDEP to nDEP and vice versa. − The magnitude of the DEP force and the crossover frequency from nDEP to pDEP (low f co1 ) and from pDEP to nDEP (high f co2 ) are highly dependent on C. necator physiology, genotype, and phenotype.…”

Dielectrophoretic Characterization of Tenogenically Differentiating Mesenchymal Stem Cells

“…Stem cells' cytoplasm and its contents, i.e., nucleus, DNA, organelles, etc., are considered one homogenous sphere surrounded by a plasma membrane to reduce complexity ( Figure 1). For a single shell model, the complex permittivity of a cell is given by [45,46]:…”

“…Stem cells’ cytoplasm and its contents, i.e., nucleus, DNA, organelles, etc., are considered one homogenous sphere surrounded by a plasma membrane to reduce complexity ( Figure 1 ). For a single shell model, the complex permittivity of a cell is given by [ 45 , 46 ]: where R is the outer radius of the cell, d is the thickness of the membrane, and the subscripts mem and cp refer to the cell membrane and cytoplasm, respectively.…”