Short term evaluation of material blood compatibility using a microchannel array

New short-term evaluation of material blood compatibility was attempted using a microchannel array with human blood under a flow condition. The microchannel array chips were made of silicon, having 8,736 microchannels of 10 microm-wide, 30 microm-long, and 4.5 microm-deep on the average, as the models of capillary blood vessels. Titanium, chromium, albumin and collagen were coated onto the chips to examine the difference of material blood compatibility and the effect of protein adsorption on it. The time for the first 100 microl portion of whole blood to pass through the channels (blood pass-through time, BPT) was measured under a pressure difference of 20 cmH2O. Simultaneously, the flow behavior of blood cells was observed by an optical microscope. The BPT tends to correlate well with the level of platelet adhesion. The highest BPT as well as platelet adhesion was observed on collagen, followed by titanium, chromium, silicon, and albumin. These results indicate that the BPT can detect the different levels of platelet adhesion and thrombus formation on microchannel surface and that the protein adsorption onto chip surface can influence BPT. We concluded that this method could be applied to evaluate initial blood compatibility of materials within several minutes in vitro.