Merging microfluidics with microarray-based bioassays

Microarray technologies provide powerful tools for biomedical researchers and medicine, since arrays can be configured to monitor the presence of molecular signatures in a highly parallel fashion and can be configured to search either for nucleic acids (DNA microarrays) or proteins (antibody-based microarrays) as well as different types of cells. Microfluidics on the other hand, provides the ability to analyze small volumes (micro-, nano- or even pico-liters) of sample and minimize costly reagent consumption as well as automate sample preparation and reduce sample processing time. The marriage of microarray technologies with the emerging field of microfluidics provides a number of advantages such as, reduction in reagent cost, reductions in hybridization assay times, high-throughput sample processing, and integration and automation capabilities of the front-end sample processing steps. However, this potential marriage is also fraught with some challenges as well, such as developing low-cost manufacturing methods of the fluidic chips, providing good interfaces to the macro-world, minimizing non-specific analyte/wall interactions due to the high surface-to-volume ratio associated with microfluidics, the development of materials that accommodate the optical readout phases of the assay and complete integration of peripheral components (optical and electrical) to the microfluidic to produce autonomous systems appropriate for point-of-care testing. In this review, we provide an overview and recent advances on the coupling of DNA, protein and cell microarrays to microfluidics and discuss potential improvements required for the implementation of these technologies into biomedical and clinical applications.