Capillarity Guided Patterning of Microliquids

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2015-06, Vol.11 (23), p.2789-2797
• Main Authors: Kang, Myeongwoo, Park, Woohyun, Na, Sangcheol, Paik, Sang-Min, Lee, Hyunjae, Park, Jae Woo, Kim, Ho-Young, Jeon, Noo Li
• Format: Article
• Language: English
• Subjects: Biological; Capillaries; Capillarity; Cell Separation - instrumentation; Channels; Equipment Design; Equipment Failure Analysis; Fluid flow; Gels; Gels - chemistry; Hydrogels; lab-on-a-chip devices; liquid patterning; Liquids; microfluidics; Microfluidics - instrumentation; Molecular Imprinting - instrumentation; Nanotechnology; Patterning; Printing, Three-Dimensional - instrumentation; Solutions - chemistry; surface tension
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201403596

Soft lithography and other techniques have been developed to investigate biological and chemical phenomena as an alternative to photolithography‐based patterning methods that have compatibility problems. Here, a simple approach for nonlithographic patterning of liquids and gels inside microchannels is described. Using a design that incorporates strategically placed microstructures inside the channel, microliquids or gels can be spontaneously trapped and patterned when the channel is drained. The ability to form microscale patterns inside microfluidic channels using simple fluid drain motion offers many advantages. This method is geometrically analyzed based on hydrodynamics and verified with simulation and experiments. Various materials (i.e., water, hydrogels, and other liquids) are successfully patterned with complex shapes that are isolated from each other. Multiple cell types are patterned within the gels. Capillarity guided patterning (CGP) is fast, simple, and robust. It is not limited by pattern shape, size, cell type, and material. In a simple three‐step process, a 3D cancer model that mimics cell–cell and cell–extracellular matrix interactions is engineered. The simplicity and robustness of the CGP will be attractive for developing novel in vitro models of organ‐on‐a‐chip and other biological experimental platforms amenable to long‐term observation of dynamic events using advanced imaging and analytical techniques. Liquid patterns, including hydrogel and cell suspension, are spontaneously formed inside micropost arrays by a simple liquid draining motion. This method takes advantage of the surface tension of the liquid and can be performed within 5 s, without special equipment or precise flow control.