Abstract: A micro-cartridge for a fluid test device has a fluid source chamber, a particulate collection chamber, a main channel extending from the fluid source chamber to the particulate collection chamber, a liquid collection chamber, and a plurality of capillary channels extending from the main channel to the liquid collection chamber. The main channel has a width within a range of about 50 ?m to 300 ?m. A method of separating liquid from a composite fluid includes obtaining a sample of the composite fluid, wherein the composite fluid includes a liquid and particulate matter suspended in the liquid, and delivering at least a portion of the composite fluid near an entrance port of a main channel of a separating device.