Adv. Mater. (2012)

Credit: © 2012 WILEY

The large porosity and chemical versatility of metal–organic frameworks (MOFs) make them attractive for their potential use in catalysis, sensing, gas storage and drug delivery. Although most efforts have concentrated on controlling the preparation of novel framework topologies and their internal functionalities, immobilization and integration of these materials in functional devices has remained elusive. Jeroen Lammertyn and colleagues now use a microfluidic approach to accurately deposit monodisperse individual MOF crystals, which leads to high-throughput yet flexible single-crystal patterning. The proposed methodology relies on a digital microfluidic platform, which is designed for the controlled delivery of femtolitre droplets of MOF building-block solutions. The hydrophobic surface of the device is patterned to obtain hydrophilic-in-hydrophobic micropatches onto which droplets of MOF precursor solution are printed per second in a chosen pattern. On controlled evaporation of these droplets, large arrays of single MOF crystals can be fabricated. Compared with other methodologies, this approach does not rely on expensive equipment and results in the flexible production of large arrays of monodisperse MOF crystals with high parallelism.