CAREER: Designing Microscale, Shape-Morphing Liquid Crystal Elastomers as Tissue Adhesives

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CAREER: Designing Microscale, Shape-Morphing Liquid Crystal Elastomers for Implantable Micromechanical Systems Non-technical abstractThis CAREER award by the Biomaterials Program in the Division of Materials Research, to the University of Texas at Dallas, is to design and characterize shape-changing liquid crystal elastomers for implantable micromechanical systems. Liquid crystal elastomers are rubbery materials that can reversibly change from one shape to another in response to changes in their environment. This shape change occurs without requiring external power and control equipment, which is particularly useful in implantable medical devices where water can disrupt circuitry, batteries are difficult to charge, and space is limited. This research effort will enable the synthesis and fabrication of liquid crystal elastomers, with dimensions smaller than a human hair, which bend, stretch, or twist near body temperature. These small structures will be able to penetrate tissue and the subsequent shape change will enable strong adhesion of synthetic materials to soft, wet, and moving tissues of the human body. This new strategy will address a critical national need for improved tissue adhesives. For example, many common treatments, such as hernia repair, require synthetic materials to adhere to the soft tissue, and adhesion failure leads to increased healthcare-related costs and pain. These smart materials will also serve as powerful tools to demonstrate basic scientific concepts to the next generation of scientists and engineers. Technical abstractThe proposed work will enable the design of biodegradable physical adhesives using the programmed shape change of microscale liquid crystal elastomers. Microneedle arrays that penetrate soft tissue and then undergo controlled shape change to enhance tissue adhesion are envisioned. The large, programmable, and reversible shape change of liquid crystal elastomers make these materials ideal candidates for the design of active microstructures. This work will overcome three critical limitations currently preventing the use of liquid crystal elastomers in biomedical applications: 1) the temperatures that induce shape change of these materials are too high for use in biomedical applications, 2) the biodegradability of these materials is uncontrolled, and 3) the shape change is difficult to program in 3D microscale structures. This award supports development of liquid crystal elastomer chemistries and post-processing strategies to tune transition temperatures and biodegradability. Furthermore, this award enables micromolding techniques to process these materials in 3D microstructures that undergo complex shape change. These active microstructures will be characterized for the ability to create mechanical adhesion to soft tissue that resists both tensile and shear loading. Research activities will be coupled to primary, secondary, and post-secondary student interactions, to help train the next generation of STEM graduates. Design-based learning modules will be created and assessed that teach fundamental concepts in chemistry and physics through the constructs of smart materials and medical devices.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.