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Although the field of microfluidics has made significant progressin bringing new tools to address biological questions, the accessibilityand adoption of microfluidics within the life sciences arestill limited. Open microfluidic systems have the potential to lowerthe barriers to adoption, but the absence of robust design ruleshas hindered their use. Here, we present an open microfluidicplatform, suspended microfluidics, that uses surface tension to filland maintain a fluid in microscale structures devoid of a ceilingand floor. We developed a simple and ubiquitous model predictingfluid flow in suspended microfluidic systems and show that itencompasses many known capillary phenomena. Suspended microfluidicswas used to create arrays of collagen membranes, mico Dots(μDots), in a horizontal plane separating two fluidic chambers,demonstratinga transwell platform able to discern collective or individualcellular invasion. Further, we demonstrated that μDots can alsobe used as a simple multiplexed 3D cellular growth platform. Usingthe μDot array, we probed the combined effects of soluble factorsand matrix components, finding that laminin mitigates the growthsuppression properties of the matrix metalloproteinase inhibitorGM6001. Based on the same fluidic principles, we created a suspendedmicrofluidic metabolite extraction platform using a multilayerbiphasic system that leverages the accessibility of openmicrochannels to retrieve steroids and other metabolites readilyfrom cell culture. Suspended microfluidics brings the high degreeof fluidic control and unique functionality of closed microfluidicsinto the highly accessible and robust platform of open microfluidics.
From:PNAS