Biomedical Engineering Reference
In-Depth Information
1.3 Scanning electron micrograph (SEM) of oxygenation membranes
produced by TIPS.
Generally, the process is also capable of producing flat sheet membranes.
One then casts the hot polymer solution on a chill roll. The principle of
membrane formation remains the same. However, such membranes have never
played a significant role in blood oxygenation. An overview of membrane pore
sizes and dimensions is given in Table 1.2.
Dry stretch
Alternatively, the capillary membrane can be produced without the use of
solvents directly from a solid capillary. For this, a capillary from PP is produced
by extrusion. The exact polymer and the extrusion conditions need to be chosen
carefully to enable the membrane production in the next steps. This capillary is
then subjected to a series of annealing and stretching and relaxation procedures
at different temperatures. Preferably, an annealing step is followed by a cold and
then a hot stretch procedure (Fig. 1.4).
Table 1.2 Dimensions and pore sizes of current blood oxygenation membranes
8,16
Inner diameter
Outer diameter Wall thickness
Pore size
(m)
(m)
(m)
(m)
OXYPHAN
Õ
200, 280
300, 380
50
0.2
OXYPLUS
Õ
200
380
90
n/a
CELGARD
Õ
150, 240
200, 300
25, 40
0:040:1
Terumo
280
380
50
0.05
