A self-defined hollow needle formation on silicon membranes with the aids of carbon nanotubes

A self-defined method for the formation of hollow needles and micro-cylindrical structures on silicon substrates is reported which uses the combination of high aspect ratio vertical etching of silicon with a small angle vacuum deposition technique. These structures can be used as the media to transfer gas and liquid through their tiny holes. The fabrication is further continued with the growth of carbon nanotubes on the already created silicon-based features to form a cage-like cylindrical structure. In addition, the growth of vertical carbon nanotubes just inside the cup-like structures has been demonstrated without a need for an extra lithography step.