University of Massachusetts Amherst

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SNAPPING SURFACES FOR SENSORS AND ADHESION CONTROL
This invention involves creating shape transition at responsive interfaces or surfaces by employing simple features such as shells, plates or columns, that are integrated into a material's surface or interface through simple processes of molding or self-assembly.  Upon application of a given stimulus (e.g. weight, light, chemical, thermal) the structures will spontaneously transform their shape due to the onset of elastic instability.  This instability is a "snap-through" event which induces the shape transition of the material surface.
Published: 11/19/2014   |   Inventor(s): Edwin Chan, Alfred Crosby, Douglas Holmes, Kyriaki Kalaitzidou, Charles Rand
Category(s): Devices & sensors, Material science
TUNABLE SURFACE WRINKLES FOR SMART ADHESION
This invention provides a novel, reusable adhesive surface with a well-defined surface wrinkle pattern as well as a facile, scalable and economical method to directly fabricate a patterned adhesive using a bottom-up approach. The patterning process involves swelling a laterally confined polymer film to develop surface wrinkles and photopolymerizing the swelling agent to stabilize the wrinkles. The control of adhesion is determined by the wavelength of the surface wrinkles, which is directly proportional to the thickness of the polymer film. Various processing parameters such as the film thickness, the polymer or swelling agent material, and the degree of lateral confinement can be adjusted to tune and control adhesion to produce truly "smart" adhesives for a variety of commercial applications.
Published: 11/18/2014   |   Inventor(s): Edwin Chan, Alfred Crosby, Ryan Hayward
Category(s): Material science, Engineering, Physical Science
BUMP: BUckled Microlens Patterns for Optics and Adhesion
This technology provides a rapid, low-cost and versatile method for fabricating microlens arrays based on surface wrinkling. Surface wrinkling is a shape instability that occurs upon the application of a critical compressive stress to a material. This fabrication method uses selective surface modification and controlled swelling of an elastomeric layer to cause spontaneous formation of aligned wrinkles and microlens structures at the modified sites of the layer. The curvature of the microlens structures can be easily tuned by adjusting the size and/or the thickness of the modified sites.
Published: 2/27/2014   |   Inventor(s): Edwin Chan, Alfred Crosby
Category(s): Material science, Devices