Encrypted Polarization Technology Developed Through Uniform Stretching Control

Professor Soo Seok Choi's POSTECH Electrical Engineering team, comprising first-author doctoral student Junhyeok Shin, doctoral student Hakjun Yang, Jiyoon Park, and Sanghyeon Han, developed uniform stretching control for multipixel next-generation stretchable smart materials. Their technology detects strain deformation and separates color and polarization. The study was published online and selected for the back cover of Advanced Functional Materials, impact factor 18.5.

Existing stretchable electronics suffer unstable performance when implementing practical multipixel devices and large patterned designs because stretching deformation is spatially nonuniform. This is particularly problematic for intrinsically stretchable materials flexible like silicone or human skin. Current approaches therefore often use extrinsic stretchability through special structures such as serpentine patterns, with limited stretch range, while progress toward ideal intrinsically stretchable multipattern/pixel devices has been difficult.

The researchers used intrinsically stretchable mechanochromic color materials, which stretch like rubber and change color with mechanical deformation, to precisely measure multipixel deformation and achieve uniform control for the first time. External deformation-control techniques, including rigid islands on soft substrates and kirigami patterns, effectively resolved nonuniform deformation. The findings are expected to advance intrinsically stretchable technologies.

The team also applied uniform, freely adjustable patterns to multipixel arrays of chiral liquid-crystal elastomers (CLCEs), which combine intrinsic stretchability with optical polarization control. They demonstrated precise control of deformation-dependent color separation and circularly polarized light selectivity. The technology opens possibilities for stretchable displays, security/encryption devices, wearable optical sensors, and applications requiring dynamic color/polarization control.

Support came from the Samsung Science & Technology Foundation and the Korea Evaluation Institute of Industrial Technology's stretchable display development and stretchable demonstration technology programs.