Fabrication of Micro/Nano-filter by building sacrificial structure with colloid crystal

Fabrication process of a novel multi-scaled filtration membrane for sample pretreatment in microfluidic system is presented in this paper. The membrane has a combinatorial structure with feature size ranging from hundred nanometers to micrometers. A nano-filtration membrane is mosaically embedded into the pores of a microfabricated membrane with crystal structure to get a high filtering flux at a reasonable mechanical strength. After assembling Polystyrene microspheres into the micro-pores and electrodepositing Cu in the interstices of the sphere crystal, a nano-porous structure with feature size of 450nm can be obtained after releasing the sacrificial micro-spheres off in oxygen plasma. All the process of the present micro/nano filtration unit is compatible with the micro-electro-mechanical systems (MEMS) technology and thereby is ready for the multifunction integration monolithically to construct a micro total analysis system.