Hollow fiber membrane and method for manufacturing thereof

Abstract

The present invention concerns a semipermeable hollow fiber membrane having an outer wall surface, an inner wall surface and an interior lumen extending along the length thereof and having the selective layer on the outer wall surface with a surface roughness below 10 nm. According to the invention the membrane has the smallest pore size on the outer wall surface, and has an outer wall surface which is smooth, continuous and homogeneous in a nanoscopic scale and four to five distinct layers of different pore size and density. Further the present invention concerns a process for manufacturing thereof and the use thereof.

1 . A microdialysis device comprising:
 a sensor membrane for direct blood applications, the sensor membrane being a semipermeable hollow fiber membrane comprising an outer wall surface being smooth, continuous, and homogeneous in a nanoscopic scale, an inner wall surface, and an interior lumen extending along the length of the semipermeable hollow fiber membrane, the semipermeable hollow fiber membrane having a selective layer on the outer wall surface, the outer wall surface having a smallest pore size and being virtually devoid of roughness with roughness parameters R a  and R q  of not more than 10 nm, roughness being measured with an atomic force microscope (AFM), and the roughness parameters R a  and R q  being calculated using the following equations:   
       
         
           
             
               
                 R 
                 a 
               
               = 
               
                 
                   
                     1 
                     N 
                   
                    
                   
                     
                       ∑ 
                       
                         i 
                         = 
                         1 
                       
                       N 
                     
                      
                     
                         
                     
                      
                     
                       
                          
                         
                           Z 
                           i 
                         
                          
                       
                        
                       
                           
                       
                        
                       
                         R 
                         q 
                       
                     
                   
                 
                 = 
                 
                   
                     
                       1 
                       N 
                     
                      
                     
                       
                         ∑ 
                         
                           i 
                           = 
                           1 
                         
                         N 
                       
                        
                       
                           
                       
                        
                       
                         Z 
                         i 
                         2 
                       
                     
                   
                 
               
             
           
         
         with N being the total number of data points and Z i  being the height of a data point above an average picture level. 
       
     
     
         2 . The device of  claim 1 , wherein the semipermeable hollow fiber membrane has a hydraulic permeability within the range of 1×10 −4  to 100×10 −4  [cm 3 /cm 2 ×bar×s]. 
     
     
         3 . The device of  claim 1 , wherein the semipermeable hollow fiber membrane comprises a polymer composition comprising polysulfone (PSU), polyethersulfone (PES) or polyarylethersulfone (PAES); and polyvinylpyrrolidone (PVP). 
     
     
         4 . The device of  claim 3 , wherein the polyvinylpyrrolidone (PVP) in the semipermeable hollow fiber membrane comprises a blend of at least two homo-polymers of polyvinylpyrrolidone (PVP), and wherein one of the homo-polymers has an average relative molecular weight within the range of 10,000 g/mol to 100,000 g/mol, and another one of the homo-polymers has an average relative molecular weight within the range of 500,000 g/mol to 2,000,000 g/mol. 
     
     
         5 . The device of  claim 1 , wherein the semipermeable hollow fiber membrane has an inner diameter within the range of 50 to 2000 μm. 
     
     
         6 . The device of  claim 1 , wherein the semipermeable hollow fiber membrane has a wall thickness within the range of 10 to 200 μm. 
     
     
         7 . The device of  claim 1 , wherein the semipermeable hollow fiber membrane has an effective diffusion coefficient through the membrane for urea (60 g/mol) within the range of 4×10 −6  to 15×10 −6  [cm 2 /s].