Fabrication of robust and reusable mold with nanostructures and its application to anti-counterfeiting surfaces based on structural colors

Nguyen Hoang Minh; Kwanoh Kim; Do Hyun Kang; Yeong-Eun Yoo; Jae Sung Yoon

doi:10.1088/1361-6528/ac1cbf

Fabrication of robust and reusable mold with nanostructures and its application to anti-counterfeiting surfaces based on structural colors

Nanotechnology. 2021 Sep 17;32(49). doi: 10.1088/1361-6528/ac1cbf.

Authors

Nguyen Hoang Minh^{1

2}, Kwanoh Kim¹, Do Hyun Kang¹, Yeong-Eun Yoo^{1

2}, Jae Sung Yoon^{1

2}

Affiliations

¹ Dept. Nano Manufacturing Technology, Korea Institute of Machinery and Materials (KIMM), Republic of Korea.
² Dept. Nano Mechatronics, Korea University of Science and Technology (UST), Republic of Korea.

PMID: 34380119
DOI: 10.1088/1361-6528/ac1cbf

Abstract

In this study, we report a method to fabricate molds and flexible stamps with 2D photonic crystal structures. This includes self-assembly of polystyrene particles into monolayer, oxygen reactive ion etching, thin film (chromium (Cr)) deposition, and polydimethylsiloxane replication. By tuning the thickness of Cr layer, reusable master molds with nano bumps or nano concaves could be prepared selectively. We showed that the replicated flexible stamps out of these molds exhibited structural colors. Characteristics of the colors depended on viewing angle, brightness of background and light source. And the colors even faded out when the background is white or when the stamp was bent. By using this feature, possible strategies for anti-counterfeiting applications have been suggested in this study. Since the molds are reusable and the fabrication method is simple and cost-effective, this study is expected to contribute to nano devices for industries in future.

Keywords: anti-counterfeiting; nanoparticle; self-assembly.