Rapid nanoliter DNA hybridization based on reciprocating flow on a compact disk microfluidic device

We present a compact disk (CD) microfluidic device capable of generating the reciprocating flow of DNA samples within the microchannels and demonstrate its application in rapid DNA hybridization assay with nanoliter-volume samples. This device consists of a polydimethylsiloxane (PDMS) CD slab containing twelve DNA hybridization functional units and a glass substrate with immobilized DNA probe array. A reciprocating flow is produced with simple rotation-pause operation of the CD device. When spinning the CD device, centrifugal force drives the sample solution to flow through the hybridization channel into the temporary collection reservoir. When stopping the rotation of the CD device, capillary action pulls the sample solution to reversely flow back into the hybridization channel because of hydrophilic surface of the hybridization channel. We used Dengue virus gene sequence (18mer) as a model to demonstrate that the reciprocating flow of DNA samples significantly enhanced the mass transfer rate in the hybridization reaction, reducing the hybridization time to 90 s. Moreover, only nanoliter-volume DNA samples were required per assay unit. We also compared the performance between the reciprocating-flow hybridization and the flow-through hybridization using the same sample concentrations. A fluorescence intensity was observed to increase up to threefold in the reciprocating-flow hybridization compared to the flow-through hybridization with the same hybridization time (90 s) and sample volumes (350 nL). This CD microfluidic device has the potential for automated, rapid and multiple DNA-based diagnostics.