This presentation describes a very simple and robust microfluidicdevice for digitizing samples into a large array of discrete volumes.The deviceis based on an inherent fluidic phenomenon,where an incoming aqueoussample divides itself into an array of chambers that have been primed with animmiscible phase.We called this the SD (Self Digitization)Chip.Self-digitization of sample volumes results from the interplay betweenfluidic forces,interfacial tension,channel geometry,and the final stability of thedigitized samples in the chambers.Unlike existing methods used to partitionsamples into an array,our method is able to digitize 100% of a sample into alocalized array without any loss of sample volume.The final volume of thedigitized sample at each location is defined by the geometry and size of eachchamber.Thus,we can also form an array of samples with varying butpredefined volumes.The digitized volumes in the SD chip also can beremoved selectively for downstream analysis,and addition of reagents to thedigitized samples is possible.The SD Chip represents a robust and versatileapproach that relies on a persistent fluidic behavior rather than complex fluidiccontrols.