Fast and maskless nanofabrication for high-quality nanochannels

Fast and maskless nanofabrication for high-quality nanochannels. [Display omitted] •This novel approach provides a fast, maskless and nondestructive fabrication strategy for high-quality nanochannels.•The proposed fabrication method eliminates the limitation of HF/HNO3 mixtures in nanofabrication.•The morphology of nanochannels can be controlled by changing the concentration of etchant and scratching load.•The nanofluidic chips fabricated by proposed method provide a good platform for nanofluid analysis. Nanochannels are critical components for the fundamental and applied studies of nanofluids. However, the intrinsic low efficiency and high cost of conventional bulk-/surface-/mold-machining methods severely hinder the wide application of nanochannels. Here, we reported a fast, low-cost and maskless fabrication strategy based on friction-induced selective etching in HF/HNO3 mixtures for controllable preparation of diversified and high-quality Si nanochannels. Owing to its distinct anisotropic etching characteristic to scratched area, this novel integrated fabrication process eliminated the limitation of HF/HNO3 mixtures in nanofabrication. Particularly, the etching efficiency and depth of scratched Si in HF/HNO3 mixtures are 12 and 2 times of those in HF solution, respectively. Furthermore, the effects of the volume ratio of HF and HNO3 as well as scratching parameters on nanochannel fabrication were investigated systematically. Cross-sectional transmission electron microscopy observation indicated that the as-fabricated nanochannels have no structural damage. Finally, the corresponding nanofluidic device was designed, fabricated and verified in sequence. The results demonstrate the feasibility of proposed approach for nanochannel fabrication in the area of nanofluids, particularly in analytical chemistry, biochemistry, liquid transport and metering, and energy conversion.