STICKY · Ultrasensitive probing of wet adhesion and charge dynamics in soft materials

Soft wet adhesion is a physical phenomenon exploited by organisms that live in wet environments to allow them to adhere to surfaces despite charge barriers that typically hinder adhesion. The physics underpinning soft wet adhesion has been studied for over a century. The interplay between charge and adhesion dynamics in soft adhesion is strongly complicated by non-linear and time-dependent effects for different compression rates and environmental conditions and remains poorly understood due to the lack of simultaneous charge and force-based experiments on pairwise interactions in dynamic conditions. Understanding charge-adhesion interplay is important for novel biomedical and engineering applications. Here, I will develop an Electro-Adhesion Microscope to probe real-time interactions between soft wet adhesion and charge at piconewton and femtocoulomb resolutions. Using a hydrogel soft probe to mimic tissue and conductive hydrogel as soft adhesive I will determine how charges vary with compression rates and stiffnesses for anionic and cationic adhesives and soft probe, and how these charge changes influence adhesion in water and complex fluids. By adopting soft probe to wet probe, I will also explore these interactions in the presence of a thin liquid film in air. Together this will resolve several major questions on charge-adhesion interplay, with the grand goal of discovering new insights into how and why charges influence soft wet adhesion dynamics. These experiments will pave the way for new research in soft matter adhesion dynamics, providing critical data on force, charge, interface deformations, and fluid dynamics for theorists and engineers in biomedical applications. The outcomes of this project will enable the creation applications such as regenerative medicine (designing scaffolds for tissue regeneration), drug delivery (creating surfaces to enhance or inhibit cellular uptake of therapeutics), and biosensing (developing susceptible detection systems).