Microchannel technologies for artificial lungs: (2) screen-filled wide rectangular channels.

Artificial lungs with blood-side channels on a 10-40 microm scale would be characterized, similar to the natural lungs, by tens of thousands to hundreds of millions parallel blood channels, short blood paths, low pressure drops, and low blood primes. A major challenge for developing such devices is the requirement that the multitude of channels must be uniform from channel to channel and along each channel. One possible strategy for developing microchannel artificial lungs is to fill broad rectangular channels with micro scale screens that can provide uniform support and stability. The present work explores the effectiveness of 40 microm screen-filled blood-side channels and, as a comparison, 82 microm screen-filled channels. Small concept-devices, consisting of a single 69 mm wide and 3 or 6 mm long channel, were tested using 30% hematocrit blood and oxygen or air on the gas side. The measured oxygen fluxes in the devices were in the range of 4 to 9 x 10(-7) moles/(min x cm(2)), with the latter close to the theoretical membrane limit. The pressure drop was in the range of 1-6 mm Hg. Extrapolating the data to a device designed to process 4 L/min suggests a required blood prime of only 35 ml.