Lateral porous silicon membranes with tunable pore size for on-chip separation

In this work, we present a novel fabrication process for the creation of lateral porous silicon membranes with tunable pore size and porosity and their integration into planar microfluidics. Since the formation of porous silicon by anodization is highly dependent on the dopant type and concentration, we use ion implantation to manipulate the local dopant concentration in order to control the membrane properties. The dead-end filtration capability of our lateral porous silicon membranes integrated within planar microchannels is demonstrated by adequately retaining 300 nm diameter beads, while molecules such as fluorescein and miRNA permeate the membranes.