Hard vs Soft Fibrillar Self-Cleaning

My paper on the self-cleaning of gecko adhesives was published in Applied Materials and Interfaces. We reported that for certain particle sizes and fiber diameters, both hard (polypropylene) and soft (PDMS) fibrillar adhesives recover adhesive capabilities to different degrees. An analysis of the contact strength between fibers, particles and substrates reveals that dry self-cleaning is more effective for smaller fiber diameters and smaller loss functions, such as hard thermoplastics.

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Magnetically Actuated Ridges

My recent work on magnetically actuating an array of microridges has been published in Advanced Functional Materials. We have shown that by controlling the angle of the 325 micron long array elements, we can controllably adhere to a range of particle sizes.

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Ridge angle can be controlled via an external magnetic field.

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Magnetic particles are mixed and cured into the liquid PDMS during casting, and aligned during curing by an external magnetic field.

Here is a link to the article: http://onlinelibrary.wiley.com/doi/10.1002/adfm.201203122/abstract

Dynamic Climbing Robot

Paul Birkmeyer and I have created a version of his CLASH robot that now includes footpads with synthetic gecko adhesive. CLASH can now rapidly climb steep acrylic up to angles of 75 degrees. Our work was published at IROS 2012.

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CLASH: Climbing Vertical Cloth

My work on Paul Birkmeyers CLASH robot has been published in IROS 2011.

During the development of CLASH, I assisted by testing the engagement properties of the feet on loose cloth substrates using a custom built 2 axis force displacement apparatus. Testing revealed that the foot-ankle linkage allowed for spines on the feet to engage with a strong tensile force, yet allow for easy retraction through a variety of angles.

The publication can be found here.

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From Paul Birkmeyers abstract: CLASH is a 10cm, 15g robot capable of climbing vertical loose-cloth surfaces at 15 cm per second. The robot has a single actuator driving its six legs which are equipped with novel passive foot mechanisms to facilitate smooth engagement and disengagement of spines. These foot mechanisms are designed to be used on penetrable surfaces and offer improved tensile normal force generation during stance and reduced normal pull-off forces during retraction. CLASH is the first known robot to climb loose vertical cloth and is able to climb surfaces when surface rigidity is not guaranteed.

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