Scraping will work for any anodization condition. Disperse the scraped material in acetone, and place a drop of this solution onto the TEM grid. Ultrasonication works well when your nanotubes are long and the residual stress is high in the anodic oxide layer. Sometimes you may slightly bend the Ti sibstrate and peel the oxide layer off of the substrate.

Polishing Electrochemical Etching

Ultrasonication treatment .....

Krishnan Raja The length of the nanotubes is about 0.55μm, is that short? According to your suggestion, I`d better bend the Ti sheet for peeling off the nanotube array from the substrate and then scrape it with a surgical blade, right?

Yana Suchikova Can you please tell me a little more about the protocol？ or is there any relevant literature to share?

Anyway, thanks for your kindly help!

Namdev S. Harale Have you done this before? How long do you think is appropriate, thanks!

I consider 550 nm as short. If the oxide layer peels off while you bend the Ti foil, then scraping by surgical blade may not be necessary. Peeling by bending or removal by ultrasonication becomes easier when the nanotubes are several micrometers long. Scarping is much simpler. Only issue is that you may break the nanotubes which makes the determination of actual length of nanotubes difficult.

Krishnan Raja Thanks！I will try it！