Coating titanium dioxide patterns on curved glass
DOI: 10.1063/10.0002434
Coating titanium dioxide patterns on curved glass lead image
Titanium dioxide (TiO2) as a photocatalytic material on curved glass surfaces could transform optical sensor performance. But depositing TiO2 films with uniform patterns has proved difficult on curved, rigid substrates.
Luo and Hu have tackled this problem by fabricating TiO2 uniform dots patterns on glass rods and even smaller glass capillary tubes. Their achievement builds on previous research
on a method called double transfer nanoimprint lithography (DTNL).
Nanoimprint lithography is used to pattern planar substrates coated with uniform resist films. Excess film is washed off to expose the pattern, which is then hardened to produce a mold for the metal oxide layer. However, resist films are difficult to produce in submicron thickness, which is vital to the subsequent reactive ion sketching and pattern transfer.
DTNL enables the production of a uniform residual layer that is etched before the liftoff process, when film is transferred onto the underlying substrate. It remains a challenge, though, to fabricate metal oxide patterns on curved surfaces, because the residual film waste is difficult to fully remove. So, the researchers eliminated the need for liftoff altogether by developing a titanium-based liquid resist film that converts directly to TiO2 after it is thermally cured.
“We have shown how TiO2 can be patterned on different curved substrates to increase the performance and flexibility in optical sensor design,” said author Xin Hu, a contributor in the development of DTNL. “In addition, the porous TiO2 dots can be tuned, making the material easier to modify and further explore with doping.”
Different patterns can be created using the same method. The researchers plan next to fabricate TiO2 patterns on flexible fibers and more fully investigate TiO2 tuning capability.
Source: “Direct imprinting of TiO2 patterns on highly curved substrates,” by Ming Luo and Xin Hu, Journal of Vacuum Science and Technology B (2020). The article can be accessed at https://doi.org/10.1116/6.0000554 .
