A hollow-cathode microplasma modified the lumenal surface of small-diameter polyethylene (PE) tubing. A microwave cavity diagnostic was used to measure the density of the microplasma. Plasma light output was observed with a monochromator at various positions along the PE tube to assess uniformity. Treatment effectiveness was evaluated by measuring the variation in capillary rise at various positions along the tubing. A correlation between the properties of the inner surface of the PE tubing and

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... the emitted light intensity was found. A poly(ethylene oxide) surfactant was immobilized to the lumenal surface of the PE tubing with an argon microplasma discharge. To test hematocompatibility, an in vitro blood-flow loop circulated heparinized human blood through both a plasma-treated and -untreated PE tubes, simultaneously. After blood exposure, the tubes were examined with a scanning electron microscope to assess the density of adhering platelets along the length of the tubes. By modifying the plasma parameters, the uniformity of the microplasma treatment along the tubing can be optimized.