Switchable Soft Photonic Bio-Adhesives*

Here, we present switchable soft photonic bio-adhesives with real-time colorimetric monitoring of reversible adhesion behavior by employing a responsive bio-photonic matrix with the dynamic hydrogen-bonding network. Synergetic materials sequencing creates a switchable structural color appearance directly correlated with both adhesion and mechanical strength in a highly reversible manner. The responsive soft photonic materials, having a strong physically hydrogen bonded chiral nematic structure, can dynamically change their adhesion and mechanical strength owed to a transition in cohesive and interfacial adhesion failure mechanism depending on the surrounding humidty. Concurrently, the dynamic hydrogen bonding feature enabled the reversible vivid color appearance shift from blue to red and transparent and vice versa, allowing tunable pitch distance of cholesteric organization. Such unique switchable strength-adhesion-iridescence triple-coupling phenomenon has never been reported before and is further applied as super-strong reversible bio-adhesives for synthetic/biological surfaces with quick remotely-provoked sticky/non-sticky transitions for biomedical and biosensing applications.