Techshot, Inc. proposes continued research and development of an on-orbit cell counter culminating in a deliverable hand-held blood cell counter in the form of a "Microfluidic Multichannel Flow Cytometer". Crew health monitoring, the Human Research Program and research in Fundamental Biology will all benefit from the availability of on-orbit cell counters that can provide immediate and repeated blood counts to assess potential anemia, neutropenia, neutrophila or possibility of infections, and signs of immune cell dysfunction. Three sequential objectives will be completed: (1) Subsystems consisting of a disposable microfluidics chip with multiple channels, fluorescence and light-scatter optics for cell detection, cell labeling protocols and reagents, electronics for controls and data processing and digital analysis and display hardware and software will be constructed and tested on the basis of Phase I research results. (2) Subsystems will be integrated into a benchtop flow cytometer for counting red and white blood cells and three subsets of white blood cells. (3) A compact hand-held cytometer device will be delivered to the sponsor. This handheld device can be operated by any on-board personnel and requires only a single drop of blood with fully automated processing of blood on-chip.