Densely-Packed Microbowl Array with Balanced Dielectrophoretic Forces for Single-Cell Microarray Maesoon Im, Dong-Haan Kim, Joo-Hyung Lee, Jun-Bo Yoon, and Yang-Kyu Choi Department of Electrical Engineering, KAIST, 335 Gwahangno Yuseong-gu, Daejeon 305-701, Republic of Korea ABSTRACT In this paper, we demonstrate a perfectly-ordered microbowl array with balanced dielectrophoresis (DEP) for a high-throughput single-cell analysis. In order to fabricate well- ordered microbowl array in a large area, we utilized three-dimensional diffuser lithography for photoresist mold and nickel electroplating technique for final microbowl structures on a silicon substrate. Single microbowl has six sharp apexes surrounding the microbowl perimeter. Each microbowl has a diameter of 10 m, and a height of 9 m, which can be controllable by patterns on mask and lithography conditions. To investigate feasibility for application to the microbowl array as a single-cell microarray, we used latex beads of 6.4 m in an average diameter to be captured by dielectrophoretic force. The nickel microbowl array densely packed with a hexagonal geometry played as a bottom electrode, and an ITO-coated glass covered the nickel microbowl array as a top electrode while keeping a uniform gap between two electrodes. After injecting solution containing latex beads through the gap, we applied an AC signal (2 V PP , 1 MHz) between two electrodes to induce high electric field near the sharp apexes of the single microbowl. A negative DEP trap is formed at the center of the single microbowl with balanced DEP force from the six apexes. The experimental result shows that injected latex beads had been successfully and uniformly aligned and trapped at the microbowl array sustained by negative DEP. INTRODUCTION This paper reports a nickel microbowl array for massive single-cell analysis with dielectrophoresis (DEP) guidance. Since cellular responses are random even under identical environmental conditions, cell biologists are eager to analyze a large number of individual cells at once to attain stochastic distributions of the cellular responses. For a high-throughput single- cell analysis, microfabrication techniques have been introduced as the various platforms: a single-cell microarray [1], which consists of microchambers accommodating an individual cell, a DEP cell-trapping array [2], a microfluidic device for single-cell assay [3], and so on. However, in the aforementioned techniques, there are disadvantages: low throughput and less-efficiency of cell-capturing promoted by only gravitational force [1], possible cell-movement after disconnecting electrical signals [2], and necessity of complicated microfluidic components [3]. It is timely to develop a new array-based technique to confine a single cell with higher density as well as without any microfluidic components. Thereby we demonstrate a perfectly-ordered microbowl array with balanced DEP forces for a high-throughput single-cell analysis as shown in Fig.1. Mater. Res. Soc. Symp. Proc. Vol. 1222 © 2010 Materials Research Society 1222-DD05-03