Microchannels typically have a relatively large surface-to-volume ratio, which can be used for the surface immobilization of reagents. For specific applications that perform better with increasing surface area, the available surface area on the inside of a microchip may not be large enough. One method to increase the effective surface area is to pack etched channels with (porous) particles. Many different types of functionalized particles are available from various sources that have already been proven to work for conventional applications
Technologies have been developed at Micronit Microfluidics that make it possible to pack channels etched in glass with various types of functionalized particles (typically smaller than 60 µm). In order to retain the particles inside the channel a shallow weir with a height of less than the particle diameter is incorporated.
Potential applications where this technology can be used include:
Advantages of packed microchips:
Channels can be packed with commercially available (proven) materials;
Plain silica particles can also be functionalized after packing using e.g. standard silanization chemistry;
Efficient mixing and heat transfer;
Reduced reagent use compared to large scale systems