Method for Measuring the Polarizability of Cells in an Inhomogeneous Alternating Electric Field

Possible Differential Diagnosis of the Degrees of Rheological Disturbances in Patients with Type 2 Diabetes Mellitus by Dielectrophoresis of Erythrocytes

“…Electric and viscoelastic parameters of RBCs were measured by dielectrophoresis by means of an electric optical system of cell detection [ 22 ]. The procedures for optical registration are explained in details in the Appendix A , which includes the functional scheme of the electric optical system of cell detection ( Figure A1 ) and the makeup of the measurement chip containing an electrode quartet ( Figure A2 ).…”

Possibilities of using electrical and viscoelastic parameters of erythrocytes for the diagnosis of steatohepatitis in patients with fatty liver disease

“…Поляризуемость клеток отражает уровень их биологической активности, жизнеспособности. Клетки в предгемолитическом состоянии продемонстрировали низкие уровни поляризуемости [25]. У пациентов со стеатогепатитом были статистически значимо снижены уровни поляризуемости на высоких частотах электрического поля -1 МГц (p<0,001) и 0,5 МГц (p=0,002), а также относительной поляризуемости (p=0,015), ассоциированной с адаптационными возможностями клеток [12].…”

Measuring Nanoparticle Polarizability Using Fluorescence Microscopy

“…While a number of techniques have been developed to measure polarizability, those that have been used with particles are largely limited to the study of microscopic objects that can be individually optically resolved. [6][7][8][9][10][11][12][13][14][15] Despite the growing importance of nanoparticles ranging from fields including nanomedicine and materials assembly, 16 there are very few techniques that are capable of quantifying the polarizability of nanoparticles, and values for the polarizability of nanoparticles in solution have not been reported. [17][18][19][20] This is especially unfortunate because theory predicts that the polarizability of nanoscale objects could change substantially as the size of the particle approaches the Debye screening length of the electrolytic fluid (Figure 1A).…”

“…DEP, in particular, has become a widely used tool for separating, sorting, trapping, and manipulating objects in solution including cells, microparticles, nanoparticles, and biomolecules. ,− Just as one needs to know an object’s ζ potential in order to predict its electrophoretic behavior, accurately predicting the effect of DEP requires measuring the polarizability of the material, which is a frequency-dependent property that depends on the composition of the particle and medium. While a number of techniques have been developed to measure polarizability, those that have been used with particles are largely limited to the study of microscopic objects that can be individually optically resolved. − Despite the growing importance of nanoparticles in diverse fields including nanomedicine and materials assembly, there are very few techniques that are capable of quantifying the polarizability of nanoparticles, and values for the polarizability of nanoparticles in solution have not been reported. − This is especially unfortunate because theory predicts that the polarizability of nanoscale objects could change substantially as the size of the particle approaches the Debye screening length of the electrolytic fluid (Figure A). − The closest experimental validation of these theories has come from impedance spectroscopy measurements, in which the impedance of dense suspensions of particles (>1% volume fraction) are studied vs frequency. − Despite focusing on relatively large particles (typically >150 nm), these studies can access regimes where the Debye length approaches the particle radius; however, connection to the individual particle polarizability is limited by operation at high volume fractions. As a further example of the need to understand how free charge affects field-induced particle motion, recent measurements and theoretical predictions of electrophoretic motion of nanoscale objects have shown that nanoscale objects behave differently with enhanced mobility emerging when the particle becomes commensurate in size with the ionic screening length. , While studies of particles are limited, measurements of the polarizability of biomolecules have proceeded over the past decades and have resulted in approaches that could potentially provide measurements of polarizability of abiotic nanoscale objects. − …”

“…Studies on the DEP behavior of micron-scale objects such as microparticles and biological cells are usually performed when | U DEP | ≫ k B T , with the Boltzmann constant k B and the absolute temperature T , indicating that DEP is substantially stronger than Brownian motion. − ,,, This, together with individual particles being optically resolvable, enables indirect quantification of α through measurements of velocity resulting from a competition between drag and DEP, ,,, the external flow speed needed to dislodge a particle from a stationary DEP trap, , or the trajectory of particles through curving fluid flows . In interpreting such measurements, material properties are typically estimated using analytical models such as the expression for a spherical particle where K is known as the Clausius–Mossotti or dipole factor given by the following: where ε̃ m is the complex permittivity of the medium, ε̃ p is the complex permittivity of the particle, and a is the radius of the particle.…”