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

职业：为可植入微机械系统设计微型变形液晶弹性体非技术摘要德克萨斯大学达拉斯分校材料研究部生物材料项目颁发的这项职业奖旨在设计和表征可植入微机械系统的变形液晶弹性体。 液晶弹性体是橡胶状材料，其可以响应于其环境的变化而可逆地从一种形状变为另一种形状。这种形状变化发生时不需要外部电源和控制设备，这在水会破坏电路、电池难以充电且空间有限的植入式医疗设备中特别有用。这项研究工作将使液晶弹性体的合成和制造成为可能，这种弹性体的尺寸比人的头发还小，在接近体温的温度下可以弯曲、拉伸或扭曲。这些小结构将能够穿透组织，随后的形状变化将使合成材料能够牢固地粘附到人体的柔软、潮湿和移动的组织上。这一新战略将满足国家对改进组织粘合剂的迫切需求。例如，许多常见的治疗，如疝修补术，需要合成材料粘附到软组织上，而粘附失败会导致医疗保健相关成本和疼痛增加。这些智能材料也将成为向下一代科学家和工程师展示基本科学概念的强大工具。技术摘要本研究将利用微尺度液晶弹性体的程序化形状变化设计可生物降解的物理粘合剂。设想了穿透软组织然后经历受控的形状变化以增强组织粘附的针阵列。液晶弹性体的大的、可编程的和可逆的形状变化使这些材料成为有源微结构设计的理想候选者。这项工作将克服目前阻碍液晶弹性体在生物医学应用中使用的三个关键限制：1）诱导这些材料形状变化的温度对于生物医学应用来说太高，2）这些材料的生物降解性不受控制，3）形状变化难以在3D微尺度结构中编程。该奖项支持液晶弹性体化学和后处理策略的开发，以调整转变温度和生物降解性。此外，该奖项使微成型技术能够在经历复杂形状变化的3D微结构中加工这些材料。这些活性微结构的特征在于能够与软组织形成机械粘附，从而抵抗拉伸和剪切载荷。 研究活动将结合小学，中学和中学后学生的互动，以帮助培养下一代STEM毕业生。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.