Dielectrophoresis microsystem with integrated flow cytometers for on‐line monitoring of sorting efficiency

Abstract

Dielectrophoresis (DEP) and flow cytometry are powerful technologies and widely applied in microfluidic systems for handling and measuring cells and particles. Here, we present a novel microchip with a DEP selective filter integrated with two microchip flow cytometers (FCs) for on-line monitoring of cell sorting processes. On the microchip, the DEP filter is integrated in a microfluidic channel network to sort yeast cells by positive DEP. The two FCs detection windows are set upstream and downstream of the DEP filter. When a cell passes through the detection windows, the light scattered by the cell is measured by integrated polymer optical elements (waveguide, lens, and fiber coupler). By comparing the cell counting rates measured by the two FCs, the collection efficiency of the DEP filter can be determined. The chips were used for quantitative determination of the effect of flow rate, applied voltage, conductivity of the sample, and frequency of the electric field on the sorting efficiency. A theoretical model for the capture efficiency was developed and a reasonable agreement with the experimental results observed. Viable and non-viable yeast cells showed different frequency dependencies and were sorted with high efficiency. At 2 MHz, more than 90% of the viable and less than 10% of the non-viable cells were captured on the DEP filter. The presented approach provides quantitative real-time data for sorting a large number of cells and will allow optimization of the conditions for, e.g., collecting cancer cells on a DEP filter while normal cells pass through the system. Furthermore, the microstructure is simple to fabricate and can easily be integrated with other microstructures for lab-on-a-chip applications.

Dielectrophoretic monitoring of microorganisms in environmental applications

“…With integrated circuits becoming more advanced and microfluidics beginning to enter the commercial world, DEP-based MEMS chips have the potential to take advantage of advances in both industries for progress in research applications in the biotechnology sector. The integration of DEP with flow cytometers has also been successfully achieved, Wang et al [139] presented a novel DEP filter device coupled to flow cytometers for online monitoring of cell sorting. Viable and nonviable yeast cells were sorted with positive DEP achieving a high efficiency; with 20 V pp at 2 MHz, more than 90% of the viable and o10% of the nonviable cells were captured on the DEP filter.…”

A high‐discernment microflow cytometer with microweir structure

“…Broadly speaking, this is achieved using either passive or active focusing techniques. The former methods generally use convergent channels to force the individual cells/particles into an orderly procession [16][17][18], while the latter typically sequence the cells/particles using hydrodynamic focusing [19][20][21][22][23][24][25], electrokinetic focusing [26][27][28][29][30], or dieletrophoretic focusing [31][32][33][34] techniques.…”

Electrokinetic motion of particles and cells in microchannels

“…This controlled gating effect was demonstrated to concentrate and separate biological materials. Wang et al (2006) integrated a selective DEP filter array with two embedded optical waveguides for online monitoring of cell sorting. Two sets of polymer optical elements constitute two microchip flow cytometers, which are located both upstream and downstream of the DEP filter array.…”