A simple electrical approach to monitor dielectrophoretic focusing of particles flowing in a microchannel

Abstract

This paper reports an impedance‐based system for the quantitative assessment of dielectrophoretic (DEP) focusing of single particles flowing in a microchannel. Particle lateral positions are detected in two electrical sensing zones placed before and after a DEP‐focusing region, respectively. In each sensing zone, particle lateral positions are estimated using the unbalance between the opposite pulses of a differential current signal obtained with a straightforward coplanar electrode configuration. The system is used to monitor the focusing of polystyrene beads of 7 or 10 μm diameter, under various conditions of DEP field intensities and flow rates that produce different degrees of focusing. This electrical approach represents a simple and valuable alternative to optical methods for monitoring of particle focusing systems.

High-throughput electrical position detection of single flowing particles/cells with non-spherical shape

“…The resulting signal is a bipolar Gaussian with asymmetric peaks (Figure 2(c)). As demonstrated in our previous work, 31,32 the pulse amplitude difference, i.e. a 2 −a 1 , conveys information on particle lateral position.…”

Positional dependence of particles and cells in microfluidic electrical impedance flow cytometry: origin, challenges and opportunities

“…The lateral focusing of 7 µm and 10 µm PS beads using liquid electrodes has been monitored by Reale et al 128 . Two impedance sensing units were placed respectively upstream and downstream of the nDEP focusing region.…”

“…It enables the compensation of impedance positional dependence in cell/particle sizing applications, obtaining very similar CVs to the size distribution of the particles (5.2, 6 and 7µm in diameter). In 2019, this method was also used to measure the position of particles before and after DEP focusing 128 . More recently, Honrado et al 140 used the new wiring scheme in two consecutive facing pairs of electrodes to measure both the lateral position and the height.…”

Oil-in-Water fL Droplets by Interfacial Spontaneous Fragmentation and Their Electrical Characterization

“…This is due to the positional dependence issue [59][60] of impedance cytometry, combined with inertial focusing mechanisms. 61,62 In fact, due to electric field non-uniformity, same size particles exhibit different electrical diameters according to their trajectory along the channel (positional dependence). In particular, with the present chip design and wiring scheme, the electric field is non-uniform across the channel height and the particles traveling at mid-height exhibit lower electrical diameter than particles traveling close to electrodes.…”