Encryption and Decryption via Dual-Phase Nematic Elastomer Films

Liquid crystalline elastomers (LCE's) can exhibit large deformations in shape due to changes in temperature or ultraviolet light; this process occur when the material transitions from an ordered liquid crystalline state to an isotropic state. Patterning an elastomer with both isotropic and ordered liquid crystalline domains can further expand the palette of possible conformations by confining the expansion and contraction of the material to specific regions. In this study, we use a finite element simulation method to model such a dual-phase material that responds only in selected regions, forming a pattern of blisters buckling out of the plane when exposed to light. If this pattern of response is agreed upon beforehand by two users, the active regions of the LCE sheet can be used to decrypt messages hidden in a photomask that determines which portions of the elastomer will be exposed to light. The active bits comprising the message will be obscured amid bits matched to the inactive regions of the elastomer, effectively concealing the message in plain sight. Our numerical model demonstrates how this encryption protocol could be implemented, and how to optimize parameters such as the active liquid crystalline patch size and spacing.