On the spontaneous formation of hierarchical wrinkles of a thin film attached to a soft substrate

2018 Fiscal Year Final Research Report

• Project/Area Number: 17H06835
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Single-year Grants
• Research Field: Materials/Mechanics of materials
• Research Institution: Osaka University
• Principal Investigator: Nagashima So 大阪大学, 工学研究科, 助教 (80800317)
• Project Period (FY): 2017-08-25 – 2019-03-31
• Keywords: ナノ・マイクロ構造 / 座屈 / 薄膜 / 変形 / ひずみ

Outline of Final Research Achievements

Mechanical instabilities of a thin film on a soft substrate generate surface patterns that can be exploited to fabricate functional materials and devices. In this study, we have uncovered the spontaneous formation of randomly oriented hierarchical wrinkles of a residually compressed thin film deposited on a soft polymer substrate and have measured characteristic dimensions of the wrinkles. When a compressive strain is uniaxially applied to the film after the wrinkle formation, the randomly oriented wrinkles begin aligning unidirectionally. As the compressive strain is increased, the aspect ratio (defined as the ratio of height to peak-to-peak distance) of the wrinkles increases, and the value remains constant for a given strain level even though the film thickness changes.

Free Research Field

材料力学

Academic Significance and Societal Importance of the Research Achievements

階層リンクルに関する研究成果は，これまでに国内外の複数の研究グループから報告されてきたが，その形成機構は未解明であり，汎用性を有した作製手法は確立されていない。本研究では，単一プロセス（薄膜蒸着）のみによる階層リンクルの自律形成現象を見出し，その発生機構を明らかにした。また，階層リンクル作製技術の確立に結びつく制御指針を獲得した。これらは，従来にない機能性人工物の創製につながる新たな知見である。