A planar interdigitated ring electrode array via dielectrophoresis for uniform patterning of cells

Uniform patterning of cells is highly desirable for most cellular studies involving cell–cell interactions but is often difficult in an in vitro environment. This paper presents the development of a collagen-coated planar interdigitated ring electrode (PIRE) array utilizing positive dielectrophoresis to pattern cells uniformly. Key features of the PIRE design include: (1) maximizing length along the edges where the localized maximum in the electric field exists; (2) making the inner gap slightly smaller than the outer gap in causing the electric field strength near the center of a PIRE being generally stronger than that near the outer edge of the same PIRE. Results of human hepatocellular carcinoma cells, HepG2, adhered on a 6 × 6 PIRE array show that cells patterned within minutes with good uniformity (48 ± 6 cells per PIRE). Cell viability test revealed healthy patterned cells after 24 h that were still confined to the collagen-coated PIREs. Furthermore, quantification of fluorescence intensity of living cells shows an acceptable reproducibility of cell viability among PIREs (mean normalized intensity per PIRE was 1 ± 0.138). The results suggest that the PIRE array would benefit applications that desire uniform cellular patterning, and improve both response and reproducibility of cell-based biosensors.