Technology

Microsieves

The microsieve used in our applications is a micro filtration membrane that is produced using patented lithography-based procedures. The most important features of these microsieves are the precision etched pores (range from 0.1-20 um) in a thin membrane (thickness of 0.5 to 5 um). The surface roughness is minimal; down to even 10 nm! The membrane material consists of silicon nitride and is strengthened by a rigid silicon support.
The microsieve has many well defined pores that are controllable by size and location in the membrane layer. The thickness in most cases is smaller than the pore size. Therefore the filter efficiency is much higher than for other filters.

Properties of the Microsieve®
Membrane Size 1 to 150 mm,
Circular or Rectangular
Membrane Thickness 0.1 to 5 µm
Pore Size 0.1 to 100 µm
Membrane Material Ceramic
Support Silicon or Other
Support Thickness 0 to 500 um
Membrane Coating Ceramic, metallic
or polymeric
Temperature Resistance -50 to 800°C
Chemical Inertness Inert to (in-)organic solvents
Surface Roughness 1 to 100nm
Protein Adsorption None
Refractive Index 1 to 2.1
Optical Flatness Yes
Operating Pressure 0 to 0.5 MPa
Cleaning Aggressive Solvent/
Oxygen Plasma
Sterilisation Yes

 

Special properties of the microsieve are:

  • Well defined pore shape
  • Uniform pore size distribution (standard deviation less than 1%)
  • Optically flat; this allows fast microscope scanning without adjusting focus
  • Smooth pores showing minimal cell rupture
Excellent pore size
Pore Perfectly controlled uniform perforations down to 0.1 um can be achieved. The separation behaviour will strongly benefit from a narrow pore size distribution. This avoids the problem related to non-uniform pore distributions, i.e. large particles slipping through the pores, particles that should have been retained. The microsieve has the most narrow pore size distribution ever possible.
Pore Size Distribution of different membranes compared  
Excellent flow rate
Pore The flow rate of the microsieve is the highest yet available due to the uniform pore size, the high pore density and the small thickness of the membrane layer. The clear water flux is at least one order of magnitude larger than the best conventional filters and approaches nearly the theoretical maximum throughout the whole pore size range.
Clear Water Flux of a Microsieve  

 

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