title: A microfabricated wedge-shaped adhesive array displaying gecko-like dynamic adhesion, directionality and long lifetime.
abstract: Gecko adhesion has become a paradigmatic example of bio-inspired engineering, yet among the many gecko-like synthetic adhesives (GSAs), truly gecko-like performance remains elusive. Many GSAs have previously demonstrated one or two features of the gecko adhesive. We present a new wedge-shaped GSA that exhibits several gecko-like properties simultaneously: directional features; zero force at detachment; high ratio of detachment force to preload force; non-adhesive default state; and the ability to maintain performance while sliding, even after thousands of cycles. Individual wedges independently detach and reattach during sliding, resulting in high levels of shear and normal adhesion during drag. This behaviour provides a non-catastrophic failure mechanism that is desirable for applications such as climbing robots where sudden contact failure would result in serious falls. The effects of scaling patch sizes up to tens of square centimetres are also presented and discussed. Patches of 1 cm(2) had an adhesive pressure of 5.1 kPa while simultaneously supporting 17.0 kPa of shear. After 30 000 attachment/detachment cycles, a patch retained 67 per cent of its initial adhesion and 76 per cent of its initial shear without cleaning. Square-based wedges of 20 mum and 50 mum are manufactured in a moulding process where moulds are fabricated using a dual-side, dual-angle lithography process on quartz wafers with SU-8 photoresist as the mould material and polydimethylsiloxane as the cast material.
authors.affiliation: Department of Mechanical Engineering, Stanford University, Escondido Mall, Stanford, CA 94305, USA. aaronparness@stanford.edu
authors.forename: Aaron
authors.initials: A
authors.lastname: Parness
authors.forename: Daniel
authors.initials: D
authors.lastname: Soto
authors.forename: Noé
authors.initials: N
authors.lastname: Esparza
authors.forename: Nick
authors.initials: N
authors.lastname: Gravish
authors.forename: Matt
authors.initials: M
authors.lastname: Wilkinson
authors.forename: Kellar
authors.initials: K
authors.lastname: Autumn
authors.forename: Mark
authors.initials: M
authors.lastname: Cutkosky