Fabrication of bottle-shaped nanochannels in fused silica using a self-closing effect

The spatial control of molecular motor function, using nanostructured surfaces, is of great interest for the development of commercial devices for diagnostics and high-throughput drug screening with molecular motors as targets. In the present study we have fabricated 100–300 nm wide nanochannels, completely subsurfaced on fused silica chips, with the aim to interface them with a microfluidic system. Such a system will allow for changes in the chemical environment surrounding molecular motors, with minimal influence on their directional motion. This will be achieved by changing the chemical environment in a perpendicular direction to the motor motion and allowing the chemical substances to diffuse in and out of the nanochannels via a small slit (5–10 nm) on the top of the nanochannels. To create this slit, and to control its width, we here demonstrate the use of a self-closing effect based on the volume increase (2.27 times) during oxidation of silicon. The details of the fabrication steps (EBL, RIE and oxidation) are discussed.

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► We have made nanochannels subsurfaced on fused silica with a narrow slit on top.
► The slit is created by a Si oxidation process creating a self-closing effect.
► We can control the nanochannel slit width and even close it.
► The key to slit width control is a stable EBL process and anisotropic RIE of Si.