Red blood cell quantification microfluidic chip using polyelectrolytic gel electrodes

Abstract

This paper reports on a novel microfluidic chip with polyelectrolytic gel electrodes (PGEs) used to rapidly count the number of red blood cells (RBCs) in diluted whole blood. The proposed microdevice is based on the principle that the impedance across a microchannel between two PGEs varies sensitively as RBCs pass through it. The number and amplitude of impedance peaks provide the information about the number and size of RBCs, respectively. This system features a low-voltage dc detection method and non-contact condition between cells and metal electrodes. Major advantages include stable detection under varying cellular flow rate and position in the microchannel, little chance of cell damage due to high electric field gradient and no surface fouling of the metal electrodes. The performance of this PGEs-based system was evaluated in three steps. First, in order to observe the size-only dependence of the impedance signal, three different sizes of fluorescent microbeads (7.2, 10.0, and 15.0 mum; Bangs laboratories, USA) were used in the experiment. Second, the cell counting performance was evaluated by using 7.2 mum fluorescent microbeads, similar in size to RBCs, in various concentrations and comparing the results with an animal hematoanalyzer (MS 9-5; Melet schloesing laboratories, France). Finally, in human blood sample tests, intravenously collected whole blood was just diluted in a PBS without centrifuge or other pretreatments. The PGE-based system produced almost identical number of RBCs in over 800-fold diluted samples to the results from a commercialized human hematoanalyzer (HST-N402XE; Sysmex, Japan).

Single-cell microfluidic impedance cytometry: a review

“…Several papers have demonstrated microfabricated microfluidic sensors for single particle counting (Tang and Gao 2005;Chun et al 2005;Cho et al 2006;Wu et al 2008a, b;Kim et al 2009) and a recent review on microfluidic systems for counting particles using electrical and optical methods has been published (Zhang et al 2009). One issue with Coulter counters is detecting small particles in a large aperture.…”

“…The lifetime of the non-polarisable Ag/AgCl electrodes is a limiting factor in the design and a typical 1 h running time was reported by the authors. Recently, a similar design (Kim et al 2009) used polyelectrolyte gel electrodes for counting RBCs.…”

Multifunctional, inexpensive, and reusable nanoparticle-printed biochip for cell manipulation and diagnosis

“…Other published designs of impedance cytometers (1,(61)(62)(63)(64) have not endeavored to reduce costs or to integrate them with other LOC analysis modules, which has limited their use for POC diagnostics in limited resource settings. Our high-throughput, ultra-low-cost, and label-free version of the classic Coulter counter constantly monitors and measures the a.c. electrical properties of particles in suspension passing through a focusing micropore (40 μm) designed in our disposable microfluidic biochip.…”

Recent advances in microfluidic techniques for single-cell biophysical characterization

“…Methods for minimizing the electrical double layer effect include the modification of the electrode surface roughness in order to increase the surface area 102 and the utilization of polyelectrolytic salt bridges (PSBEs) 103 or polyelectrolyte gel electrodes (PGEs). 104 Most recently, a DC impedance-based microcytometer device integrating PGEs was reported for CTC cell detection. Sheath flow is used for focusing cells and preventing cell adhesion to chambers and channels (see Fig.…”