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Research ArticleParameter Screening in Microfluidics Based HydrodynamicSingle-Cell TrappingB. Deng, 1 X. F. Li, 1 D. Y. Chen, 1 L. D. You, 2 J. B. Wang, 1 and J. Chen 11State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences,Beijing 100190, China2 Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada M5S 3G9Correspondence should be addressed to L. D. You; youlidan@mie.utoronto.ca, J. B. Wang; jbwang@mail.ie.ac.cnand J. Chen; chenjian@mail.ie.ac.cnReceived 11 March 2014; Accepted 4 May 2014; Published 9 June 2014Academic Editor: Ya ChengCopyright © 2014 B. Deng et al. T h is is an open access article distributed under the Creative Commons Attribution License, whichpermits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Microf l uidic cell-based arraying technology is widely used in the f i eld of single-cell analysis. However, among developeddevices, there is a compromise between cellular loading ef f i ciencies and trapped cell densities, which deserves further analysisand optimization. To address this issue, the cell trapping ef f i ciency of a microf l uidic device with two parallel micro channelsinterconnected with cellular trapping sites was studied in this paper. By regulating channel inlet and outlet status, the microf l uidictrapping structure can mimic key functioning units of previously reported devices. Numerical simulations were used to model thiscellulartrappingstructure,quantifyingtheef f ectsofchannelon/of f statusandtrappingstructuregeometriesonthecellulartrappingef f i ciency. Furthermore, the microf l uidic device was fabricated based on conventional microfabrication and the cellular trappingef f i ciency was quantif i ed in experiments. Experimental results showed that, besides geometry parameters, cellular travellingvelocities and sizes also af f ected the single-cell trapping ef f i ciency. By f i ne tuning parameters, more than 95% of trapping siteswere taken by individual cells. T h is study may lay foundation in further studies of single-cell positioning in microf l uidics and pushforward the study of single-cell analysis.1. IntroductionT h e goal of current cellular biology studies is to understandthe molecular mechanisms underlying cellular functions [1].Most cell-based assays (e.g., western blot and bulk PCR)collect data averaged across large cell populations and thusoverlook rich information available when single cells arestudied. Meanwhile, it has been known that individual cellswith identical appearances dif f er in biological propertiesas cellular heterogeneity. Due to this heterogeneity, muchef f ort has been devoted over the past few years in tech-nical developments to study cells in the single-cell level[2, 3].Among these developed methods, f l ow cytometry isthe most commonly used method for single-cell analysis,enabling simultaneous multiparametric analysis of the bio-physical/biochemical properties of single cells in a high-throughput manner [4]. Although powerful, f l ow cytometrycannot monitor temporal changes of single cells understimulation and thus its functionality in understanding cel-lular molecular mechanisms is limited [5].Quantitative microscopy enables single-cell monitoringin a time-lapse manner where both biophysical (e.g., cellularmorphology) and biochemical information (e.g., calciumconcentration)canbeobtained[1].However,inconventionalculturef l asks,uniformenvironmentsofsinglecellscannotbeguaranteed due to nonuniform distributions of biochemicaland biophysical cues (e.g., glucose, oxygen, and local f l uidf l ow). T h us, microscopy based single-cell analysis usingconventional culture f l aks leads to compromised results [5].Recently,microf l uidicsisunderintensiveresearch,whichis the science and technology of manipulation and pro-cessing of small amounts of f l uids [6, 7]. Since its criticaldimension is in the microscale, microf l uidics has been usedto capture, culture, stimulate, and retrieve single biologicalcells [8–10]. In the f i eld of single-cell capture, both activeHindawi Publishing Corporatione Scientif i c World JournalVolume 2014, Article ID 929163, 8 pageshttp://dx.doi.org/10.1155/2014/929163