Engineering Dynamic Structural Color Pixels at Microscales by Inhomogeneous Strain-Induced Localized Topographic Change

Structural colors in homogeneous elastomeric materialspredominantlyexhibit uniform color changes under applied strains. However, juxtaposingmechanochromic pixels that exhibit distinct responses to applied strainremains challenging, especially on the microscale where the demandfor miscellaneous spectral information increases. Here, we presenta method to engineer microscale switchable color pixels by creatinglocalized inhomogeneous strain fields at the level of individual microlines.Trenches produced by transfer casting from 2.5D structures into elastomersexhibit a uniform structural color in the unstretched state due tointerference and scattering effects, while they show different colorsunder an applied uniaxial strain. This programmable topographic changeresulting in color variation arises from strain mismatch between layersand trench width. We utilized this effect to achieve the encryptionof text strings with Morse code. The effective and facile design principleis promising for diverse optical devices based on dynamic structuresand topographic changes.

Automated summary

In this study, we have developed a method to engineer microscale switchable color pixels by creating localized inhomogeneous strain fields at the level of individual microlines. Trenches produced from 2.5D structures into elastomers exhibit uniform structural colors in the unstretched state, but show different colors under applied strain. This programmable topographic change resulting in color variation is achieved through strain mismatch between layers and trench width, and can be utilized for various optical devices based on dynamic structures and topographic changes.