Abstract

Biological tissues undergo dramatic and functional shape transformations during development and operation. In contrast, engineering materials are typically stiff and lifeless. In this talk, I will discuss how we engineer soft-solids to obtain lifelike complex morphing. Firstly, I will highlight how even simple elastomers and gels can exhibit rich shape-switching via elastic instabilities, including new fingering and beading instabilities, and a mechanical theory of brain folding. Secondly, I will introduce an emerging class of active soft solid, liquid crystal elastomers (LCEs), that produce muscle-like uniaxial contraction in response to heat and light. Spatial patterning of the contractile direction during fabrication enables LCEs to undergo programmed morphing on stimulation, mimicking the complex growth patterns that underpin morphogenesis. I will showcase a suite of tools for designing, simulating, and manufacturing such patterns, enabling complex actuation and robotic functions including lifting, grabbing, haptic pixels, and pumping. Lastly, LCEs also show a material-mechanism, in which the alignment rotates within the LCE under strain. The resultant “soft elasticity” introducing new instabilities, enables the facile manufacture of arbitrarily programmed shape morphers, and, looking ahead, shows great promise for the in-vivo tailoring of biomedical implants.