Programmable Curvature in Liquid Crystal Elastomers for Fabrication of 3D Electronics

Abstract

Curved electronics hold immense promise for applications ranging from flexible displays to biomedical devices. Transitioning from conventional planar fabrication to three-dimensional (3D) geometries remains a significant challenge. To manufacture 3D electronics, either the patterning process must be adapted to 3D forms, or planar substrates must be deformed into 3D shapes. Liquid crystal elastomers (LCEs) offer a promising platform by enabling intrinsic shape change from flat to intricate 3D forms through controlled molecular alignment. By patterning LCE surfaces with conductive traces prior to deformation, curved electronics can be fabricated using established planar deposition methods. Cross-linking LCEs with programmed molecular alignment at elevated temperatures allows for the fabrication of films that can adopt tunable normal and Gaussian curvature near room temperature. Increasing the nematic–isotropic transition temperature (T_NI) of the LCE allows for a wide range of cross-linking temperatures, which in turn allows for the magnitude of the deformation to be controlled. Here, we present a tunable LCE composition with a T_NI up to 162 ± 2 °C. Moreover, we fabricate hemispherical films with radii of curvature ranging from 24.57 ± 2.46 to 41.31 ± 2.82 mm at room temperature. Additionally, the effect of metallization on the deformation of LCEs into 3D forms is characterized. We envision applications for this 3D electronic fabrication platform for wearable devices in health monitoring systems designed to integrate with curvilinear human anatomy.