  Round hollow fiber membranes are long-established in applications such as gas
separation, ultrafiltration and blood dialysis. Yet, it is well known that
geometrical topologies can introduce secondary ow patterns counteracting mass
transport limitations, stemming from diffusion resistances and fouling. We
present a new systematic method- ology to fabricate novel membrane
architectures. We use the freedom of design by 3D-printing spinnerets, having
multiple bore channels of any geometry. First, such spinnerets are stationary
to fabricate straight bore channels inside a monolithic membrane. Second, in an
even more complex design, a new mechanical system enables rotating the
spinneret. Such rotating multibore spinnerets enable (A) the preparation of
twisted channels inside a porous monolithic membrane as well as (B) a helical
twist of the outside geometry. The spun material systems comprise classical
polymer solutions as well as metal-polymer slurries resulting in solid porous
metallic monolithic membrane after thermal post-processing. It is known that
twisted spiral-type bore channel geometries are potentially superior over
straight channels with respect to mass and heat polarization phenomena, however
their fabrication was cumber- some in the past. Now, the described methodology
enables membrane fabrication to tailor the membrane geometry to the needs of
the membrane process.
