Preparation of rhombus-shaped micro/nanofluidic channels with dimensions ranging from hundred nanometers to several micrometers.

Nanofluidic devices are of great interest due to their promising applications in biological/chemical detection and miniaturized power supplies. A rhombus-shaped channel with nanometer-sized opening is of particular interest as it can induce versatile symmetry-breaking phenomena such as current gating and rectification, hysteresis, biomolecule stretching etc. However, existing nanofabrication techniques, such as electron beam lithography, are usually costly and time-consuming as the target pattern has a spectrum of characteristic dimensions varying from nanometers to micrometers. In this work, a rhombus-shaped micro/nanofluidic channel with lateral dimension as small as a few hundred nanometers was prepared by depositing SiO2 into a pre-etched microchannel. The low pressure chemical vapor deposition (LPCVD) guaranteed excellent step coverage during the deposition and a 2.1 microm-thick SiO2 filling shrank the original micrometer-sized opening down to 150 nm. By this etching-filling process, fluidic devices with feature size ranging from hundred nanometers to several micrometers can be fabricated as a single monolith, thereby facilitating the fabrication of composite micro/nanofluidics systems.