Functional surface manipulation in micro- and nanofluidic devices

In this thesis, we have explored several small branches related to micro-nanofluidics. Our primary focus was on the phenomenon of a graphene blister suspended in a liquid environment and driven by voltage. Firstly, from an experimental standpoint, we investigated the influence of factors such as the initial suspension area and voltage threshold on this phenomenon. Building upon the experimental observations, we delved into the theoretical aspects. Specifically, we analyzed the impact of elastic stretching energy and elastic bending energy on the blister angle during the formation of a graphene blister. Furthermore, we deduced the maximum bending angle of a graphene blister under theoretical conditions. Additionally, we demonstrated a nano-machining technique using electrical breakdown by AFM tip to fabricate nanopores, nanostrips, and other nanostructures on demand by scanning voltage or applying a constant voltage while moving the tip. Through measuring the electrical current, we quantitatively derived the formation process on single-layer materials. We also reported a fast optical-induced wetting-state transition surface achieved by inorganic coating, enabling transitions in tens of seconds for a wetting–dewetting cycle. Moreover, we demonstrated a gravity-driven microfluidic reactor and switched it to a mixer after a second-step exposure within a minimum of 80 seconds of UV exposure. The fast wetting–dewetting transition surfaces enable rapid switchable or erasable smart surfaces for water collection, miniature chemical reactions, or sensing systems.