Scalable fabrication of gap-plasmon-based dynamic and chromogenic nanostructures by capillary-interaction driven self-assembly of liquid-metal

Dynamically tunable nanoengineered structures for coloration show promising applications in sensing, displays, and communication. However, their potential challenge remains in having a scalable manufacturing process over large scales in tens of cm of area. For the first time, we report a novel approach for fabricating chromogenic nanostructures that respond to mechanical stimuli by utilizing the fluidic properties of polydimethylsiloxane (PDMS) as a substrate and the interfacial tension of liquid metal-based plasmonic nanoparticles. Relying on the PDMS tunable property and a physical deposition method, our approach is single-step, scalable, and does not rely on high carbon footprint lithographic processes. By tuning the oligomer content in PDMS, we show that varieties of structural colors covering a significant gamut in CIE coordinates are achieved. We develop a model which depicts the formation of Ga nanodroplets from the capillary interaction of oligomers in PDMS with Ga. We showcase the capabilities of our processing technique by presenting prototypes of reflective displays and sensors for monitoring body parts, smart bandages, and the capacity of the nanostructured film to map force in real time. These examples illustrate this technology's broad range of applications, such as large-area displays, devices for human-computer interactions, healthcare, and visual communication.