Electro-rotation: development of a technique for dielectric measurements on individual cells and particles

Arnold, W.M.; Zimmermann, U.

doi:10.1016/0304-3886(88)90027-7

Cited by 241 publications

(127 citation statements)

References 50 publications

Supporting

Mentioning

123

Contrasting

Order By: Relevance

“…(1b), (3), (6), and (7) can be replaced by its effective value, 4,20 which takes into account the additional surface conductance associated with the double layer effect outside the particle (cell). Equation (3) or (7) shows a linear relationship between f pk R or f co R and r 1 .…”

Section: Theory a Current Theorymentioning

confidence: 99%

“…The result under the approximation of Level 5 gives the classical literature result. 4,20 The result using the Level 4 approximation, for the case r 1 10 À2 S=m, will now be discussed.…”

Section: Linear Theory For Medium Conductivity Less Than 001 S=mmentioning

confidence: 99%

“…Dielectrophoresis (DEP) and electrorotation (ER) were employed extensively in particle=cell manipulation [1][2][3] and characterization [4][5][6][7][8] in the literature. DEP (or ER) is a phenomenon associated with the movement (or rotation) of a particle or cell under the action of a non-uniform (or uniformly rotating) electric field.…”

Section: Introductionmentioning

confidence: 99%

“…The procedures consist of suspending the cells in a medium of conductivity r 1 and permittivity e 1 , and applying a non-uniform stationary ac field for DEP experiments 8,19,20 or a uniform rotating ac field for ER experiments. 4,20 Details of the apparatus and procedures can be found from the literature. 19,20 The measurements that are usually analyzed are the DEP cross-over frequency f co , defining the transition frequency between positive and negative DEP, and the peak frequency f pk at which the electrorotation rate attains its maximum value.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Refinement of the theory for extracting cell dielectric properties from dielectrophoresis and electrorotation experiments

2011

View full text Add to dashboard Cite

A modified theory is proposed for extracting cell dielectric properties from the peak frequency measurement of electrorotation (ER) and the crossover frequency measurement of dielectrophoresis (DEP). Current theory in the literature is based on the low frequency (DC) approximations for the equivalent cell permittivity and conductivity, which are valid when the measurements are performed in a medium with conductivity less than 1 mS=m. The present theory extracts the cell properties through optimizing an expression for the medium conductivity in terms of the peak ER, or DEP crossover, frequency according to its definition using full expressions of equivalent cell permittivity and conductivity. Various levels of approximation of the theory are proposed and discussed through a scaling analysis. The present theory can extract both membrane and interior properties from the low and the high peak ER, or DEP crossover, frequencies for any medium conductivity provided the peak ER, or DEP crossover, frequency exists. It can be reduced to the linear theory for the low peak ER and DEP crossover frequencies in the literature when the medium conductivity is less than 10 mS=m. However, we can determine the membrane capacitance and conductance via the slope and intercept, respectively, of the straight line fitting of the ER peak and DEP frequency against medium conductivity data according to the linear theory only when the intercept dominates the experimental uncertainty, which occurs when the medium conductivity is less than 1 mS=m in practice.

show abstract

Section: Theory a Current Theorymentioning

confidence: 99%

“…The result under the approximation of Level 5 gives the classical literature result. 4,20 The result using the Level 4 approximation, for the case r 1 10 À2 S=m, will now be discussed.…”

Section: Linear Theory For Medium Conductivity Less Than 001 S=mmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Refinement of the theory for extracting cell dielectric properties from dielectrophoresis and electrorotation experiments

2011

View full text Add to dashboard Cite

show abstract

“…Although rotation of cells can be observed in static electric fields, more reproducible electrorotation can be obtained if the cell is subjected to a rotating electric field. Such rotating electric fields can easily be generated by applying four signals that are 90 degree phase-shifted relative to each other to four electrodes surrounding a cell 20 (see also Fig. 3).…”

Section: Electrospinningmentioning

confidence: 99%

The use of electric fields in tissue engineering

Markx¹

2008

Organogenesis

View full text Add to dashboard Cite

Dielectric properties of alginate beads and bound water relaxation studied by electrorotation

et al. 1999

View full text Add to dashboard Cite

The electrical and dielectric properties of Ba 2ϩ and Ca 2ϩ cross-linked alginate hydrogel beads were studied by means of single-particle electrorotation. The use of microstructured electrodes allowed the measurements to be performed over a wide range of medium conductivity from about 5 mS/m to 1 S/m. Within a conductivity range, the beads exhibited measurable electrorotation response at frequencies above 0.2 MHz with two well-resolved co-and antifield peaks. With increasing medium conductivity, both peaks shifted toward higher frequency and their magnitudes decreased greatly. The results were analyzed using various dielectric models that consider the beads as homogeneous spheres with conductive loss and allow the complex rotational behavior of beads to be explained in terms of conductivity and permittivity of the hydrogel. The rotation spectra could be fitted very accurately by assuming (a) a linear relationship between the internal hydrogel conductivity and the medium conductivity, and (b) a broad internal dispersion of the hydrogel centered between 20 and 40 MHz. We attribute this dispersion to the relaxation of water bound to the polysaccharide matrix of the beads. The dielectric characterization of alginate hydrogels is of enormous interest for biotechnology and medicine, where alginate beads are widely used for immobilization of cells and enzymes, for drug delivery, and as microcarriers for cell cultivation.

show abstract

Electro-rotation: development of a technique for dielectric measurements on individual cells and particles

Cited by 241 publications

References 50 publications

Refinement of the theory for extracting cell dielectric properties from dielectrophoresis and electrorotation experiments

Refinement of the theory for extracting cell dielectric properties from dielectrophoresis and electrorotation experiments

The use of electric fields in tissue engineering

Dielectric properties of alginate beads and bound water relaxation studied by electrorotation

Contact Info

Product

Resources

About