Patterning Surface By PDMS Wrinkled Template-Based Decal Transfer Lithography

In recent years, patterned surfaces have been widely applied in optics, sensors, electronics and biotechnology. So far, a lot of patterning techniques have been developed, however, how to fabricate the highly ordered microstructures at a large scale with a simple rapid method is still a great challenge.In this thesis, patterning surface by wrinkled PDMS template-based decal transfer lithography has been systematically investigated on different substrates with varied stiffness.Here the wrinkled PDMS template is produced by oxygen plasma exposure of the uniaxially strained PDMS substrate, followed by slow release of the mechanical strain. Then according to the decal transfer-printing lithography, patterning surfaces is carried out on two typical substrates: rigid Si wafer and elastic PDMS substrate. It is found that the relative stiffness between the substrate and the PDMS wrinkled template determines the transfer direction of the resulting patterns. When the substrate is stiffer(e.g., Si), the transfer direction is from the template to the substrate. While when the substrate is softer(e.g., PDMS), the transfer direction is from the substrate to the template. Herein, the relative stiffness of the wrinkled PDMS template and the PDMS substrate can be modulated by the exposure duration of oxygen plasma and UV-ozone. Meanwhile the corresponding transfer height of the resulting patterns has been controlled as well.What's more, well-organized composite patterns resulting from the transferred patterns and the wrinkling-drived ones have been fabricated, when the above decal transfer lithography is performed on the strained PDMS substrate followed by the release of the strain. Similarly, hierarchical patterns have also been obtained on the PDMS substrate through two times' decal transfer lithography coupled with smart arrangement of the CD template and the wrinkled PDMS template.