Dielectrophoretic spectra of translational velocity and critical frequency for a spheroid in traveling electric field

Abstract

An analysis has been made of the dielectrophoretic ͑DEP͒ forces acting on a spheroidal particle in a traveling alternating electric field. The traveling field can be generated by application of alternating current signals to an octapair electrode array arranged in phase quadrature sequence. The frequency dependent force can be resolved into two orthogonal forces that are determined by the real and the imaginary parts of the Clausius-Mossotti factor. The former is determined by the gradient in the electric field and directs the particle either toward or away from the tip of the electrodes in the electrode array. The force determined by the imaginary component is in a direction along the track of the octapair interdigitated electrode array. The DEP forces are related to the dielectric properties of the particle. Experiments were conducted to determine the DEP forces in such an electrode arrangement using yeast cells ͑Saccharomyces cervisiate TISTR 5088͒ with media of various conductivities. Experimental data are presented for both viable and nonviable cells. The dielectric properties so obtained were similar to those previously reported in literature using other DEP techniques.

High-throughput electrokinetic bioparticle focusing based on a travelling-wave dielectrophoretic field

“…There are two conditions for stable twDEP movement: when the real component of CM factor is kept negative to produce a repulsive force by negative DEP, ensuring that particles are levitated from the electrodes, and when the imaginary component is close to the maximum, such that the corresponding twDEP force can induce motion along or opposing the travelling wave electric field (Hughes et al 1996). twDEP was widely used for manipulating, separating and concentrating bioparticles (Talary et al 1996;Wang et al, 1997;Bunthawin et al 2010). Balancing the twDEP force (Eq.…”

Highlighting the uniqueness in dielectrophoretic enrichment of circulating tumor cells

“…There are several DEP variants, which use different approaches to generate the electric field strength gradient: In electrode‐based DEP (eDEP), the electrodes are in contact with the media, while the electric field strength gradient is generated through the shape and size of the electrodes and their positioning in the microfluidic channel . In insulating DEP (iDEP), the electric field strength gradient is generated by the presence of dielectric posts or obstacles . In contactless DEP (cDEP), the electrodes are capacitively coupled to a microfluidic channel through a thin insulating membrane . Optical DEP is based on an image projected onto a photodiode surface which generates the gradient of the electric field . Other methods include traveling‐wave DEP (TWDEP), electrorotation (ROT), and medium conductivity gradient DEP . TWDEP is in fact a version of eDEP with the electric field strength gradient generated by changing the phase of the applied electric field . In ROT, the target cell is placed between four electrodes and the rotation speed of the cell is recorded when a 90° phase excitation signal is applied to the electrode (Fig.…”

A Tunable Microfluidic Device for Drug Delivery

“…DEP is an efficient nondestructive way to manipulate bioparticles (Cheng et al, 2011), and twDEP is being investigated as a possible drug delivery technique (Bunthawin et al, 2010). The electrode configuration consists of an array of parallel rectangular electrodes configured in an intercalated pattern as shown in Figure 1(ib).…”