Using bulk micromachining – a combination of anisotropic etching in potassium hydroxide solution, local oxidation of silicon and plasma etching of silicon – the team has produced an array of parallel nanogrooves on 100- and 110-orientated silicon wafers. The grooves are covered using a deposition method (or by tilted evaporation) to form enclosed channels. Finally, buffered hydrofluoric acid is applied at the wafer's edge to etch "V" shaped inlets and outlets along either side of the nanoarray.
The group has fabricated grooves of different widths from 200 down to 40 nm and observes no blockage of the channel during the deposition (or tilted evaporation) step.
"Our device is made totally from silicon dioxide without any nanolithography tools, so this material is transparent and hydrophilic, which makes it very good for optical inspection," B J Kim of the University of Tokyo's Institute of Industrial Sciences told nanotechweb.org. "In our opinion, the chip is well suited for single DNA manipulation and for understanding the physics of DNA under nanoscale confinement."
Initial experiments confirm that single DNA molecules stained with fluorescent dye are stretched effectively in the nanochannels. DNA molecules were transported into the channels by capillary force and imaged by both a fluorescence microscope and an image intensifier CCD camera.
The team is planning to work with other substrates, such as silicon and quartz, as well as incorporating electrodes into its design to probe the electrical properties of various biomolecules.
The researchers presented their work in Nanotechnology.