MMAE Seminar - Dr. Aiva Simaite - Towards Contamination-resistant Gecko-like Adhesives

Armour College of Engineering's Mechanical, Materials & Aerospace Engineering Department will welcome Dr. Aiva Simaite, on Wednesday, February 7th, 2018, to present her lecture, Towards Contamination-resistant Gecko-like Adhesives.

Abstract

Controllable adhesives (i.e. those capable of turning on and off) are useful for numerous applications, especially robotic and biomedical. So far, the most promising mechanisms to control adhesion relies on the gecko-inspired anisotropic adhesion of microstructured arrays, i.e. strong normal adhesion becomes available when the adhesive is loaded in shear and low-to-zero normal adhesion is available when loaded solely in the normal direction. However for practical applications, adhesives must be reusable for thousands to tens of thousands of cycles. That means that materials need to be developed for both increased adhesion and resistant to dust and similar contamination. To create such surfaces, we first studied the influence of various material properties on adhesion strength. We considered two cases: 'pillar-shaped' adhesives loaded in the normal direction and 'wedge-shaped' adhesives loaded in shear. We have shown that dissipative materials do not significantly contribute to the adhesion strength of microstructured surfaces, and, in fact, cause detrimental sliding of the 'wedge-shaped' adhesives when loaded in shear. These findings inspired two strategies towards strong, dust-resistant surfaces. First, we have created 'double-composites,' with one additive increasing the adhesion and the second one, decreasing the adhesion to contamination. Second, we have developed a post-treatment method to tune the mechanical and adhesion properties of the microstructured silicone elastomer layer-by-layer. Both strategies showed significant improvements in contamination resistance or self-cleaning without detrimental effects to the adhesion strength.