title: Highly Anisotropic Adhesive Film Made from Upside-Down, Flat, and Uniform Vertically Aligned CNTs.
abstract: We have created a multifunctional dry adhesive film with transferred vertically aligned carbon nanotubes (VA-CNTs). This unique VA-CNT film was fabricated by a multistep transfer process, converting the flat and uniform bottom of VA-CNTs grown on atomically flat silicon wafer substrates into the top surface of an adhesive layer. Unlike as-grown VA-CNTs, which have a nonuniform surface, randomly entangled CNT arrays, and a weak interface between the CNTs and substrates, this transferred VA-CNT film shows an extremely high coefficient of static friction (COF) of up to 60 and a shear adhesion force 30 times higher (12 N/cm2) than that of the as-grown VA-CNTs under a very small preloading of 0.2 N/cm2. Moreover, a near-zero normal adhesion force was observed with 20 mN/cm2preloading and a maximum 100-μm displacement in a piezo scanner, demonstrating ideal properties for an artificial gecko foot. Using this unique structural feature and anisotropic adhesion properties, we also demonstrate effective removal and assembly of nanoparticles into organized micrometer-scale circular and line patterns by a single brushing of this flat and uniform VA-CNT film.
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, Northeastern University , Boston Massachusetts 02115, United States.
authors.forename: Sanghyun
authors.initials: S
authors.lastname: Hong
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, Northeastern University , Boston Massachusetts 02115, United States.
authors.forename: Troy
authors.initials: T
authors.lastname: Lundstrom
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, Northeastern University , Boston Massachusetts 02115, United States.|Department of Mechanical & Aerospace Engineering, University of Central Florida , Orlando, Florida 32816, United States.
authors.forename: Ranajay
authors.initials: R
authors.lastname: Ghosh
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, Northeastern University , Boston Massachusetts 02115, United States.
authors.forename: Hamed
authors.initials: H
authors.lastname: Abdi
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, Northeastern University , Boston Massachusetts 02115, United States.
authors.forename: Ji
authors.initials: J
authors.lastname: Hao
authors.affiliation: Korea Automotive Technology Institute , Cheonan-Si 330-912, Korea.
authors.forename: Sun Kyoung
authors.initials: SK
authors.lastname: Jeoung
authors.affiliation: FM Global , Norwood, Massachusetts 02062, United States.
authors.forename: Paul
authors.initials: P
authors.lastname: Su
authors.affiliation: Department of Polymer Science & Engineering, Department of Energy Science, Sungkyunkwan University , Suwon 440-746, Korea.
authors.forename: Jonghwan
authors.initials: J
authors.lastname: Suhr
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, Northeastern University , Boston Massachusetts 02115, United States.
authors.forename: Ashkan
authors.initials: A
authors.lastname: Vaziri
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, Northeastern University , Boston Massachusetts 02115, United States.
authors.forename: Nader
authors.initials: N
authors.lastname: Jalili
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, Northeastern University , Boston Massachusetts 02115, United States.
authors.forename: Yung Joon
authors.initials: YJ
authors.lastname: Jung
keywords: anisotropic adhesion; high static friction; low adhesion; transfer process; vertically aligned carbon nanotubes