The invention relates to microfluidic devices and array disks for “one-pot” isolated chemical reactions. The array disks comprise a plurality of sectors in which each sector comprises one microfluidic device. The microfluidic devices comprise a fluid delivery channel and an array of wells wherein the fluid delivery channel delivery fluid into the wells in a serpentine arrangement. In some embodiments, the fluid delivery channel is directly above the array of wells. In other embodiments, the fluid delivery channel is offset from the array of wells so that side channels branching from the fluid delivery channel delivers fluid into the wells. The well of the microfluidic device comprises a gas-permeable membrane that forms the floor, well, or at least a portion of the floor or wall of the well. In preferred embodiments, the well is cylindrical.