CAREER: Mechanics-Driven Energy Dissipation in Soft Matter Lubrication

这个教师早期职业发展计划（CAREER）奖支持的研究，将有助于新的知识，设计水合，软材料表面的基础上，他们应该如何执行时，另一个表面对他们的幻灯片。水凝胶材料已经用于软性隐形眼镜和生物医学涂层（例如用于假肢），因为它们具有透水性、生物相容性和顺应性。然而，它们的表面滑移行为还没有明确的设计规则，因为它们的水合性质和广泛的能力，以调整组成。该奖项将允许高素质的学生检查滑动的机制，并将他们的发现联合收割机结合到这些水凝胶表面的更具体的设计规则中。这要求他们从多个学科中汲取知识，包括材料科学，机械工程，表面科学，甚至生物力学。这项工作将有助于征聘和鼓励工程领域代表性不足的群体。PI将参加两个正在进行的针对代表性不足的K-12学生的夏令营，并将扩大这些夏令营的课程，让来自行业的女工程师领导基于润滑科学的教育活动。具体的互动将侧重于突出行业领导者的个人经历，以鼓励营参与者追求STEM职业。PI还将利用大型本科课程活动，特别是设计经验，让学生接触到成功的本科和研究生研究。其基础性成果有望推动科学进步，提高国民健康水平。在人类中，软骨层提供强大的润滑和机械阻尼，以及化学和生物功能。水合软表面中的能量耗散机制，特别是在接触和滑动下的能量耗散机制尚未被整理出来，因此目前没有办法设计支撑载荷和控制滑动的假体装置所需的润滑行为。这项工作探讨执政理论，以他们的能力来考虑下滑移的能量耗散，包括流体负载支持，粘弹性松弛，和流体剪切。机械变形和接触的实验将证明或反驳不同机制的特征，例如摩擦系数对压力的依赖性。材料成分也将有所不同，其结果将被组装成软水合表面的指导设计原则。这项工作的研究目标的补充是增加在伊利诺伊州和美国的STEM专业人员的多样性的教育目标，通过与行业合作的高中外展活动，并利用大型本科课程活动接触研究。这个奖项反映了NSF的法定使命，并已被认为是值得支持的评估使用基金会的智力价值和更广泛的影响审查标准。

This Faculty Early Career Development Program (CAREER) award supports research that will contribute to new knowledge for designing hydrated, soft material surfaces based on how they should perform when another surface slides against them. Hydrogel materials are already used for soft contact lenses and biomedical coatings (for example for prosthetics) because they are water-permeable, biocompatible, and compliant. However, their surface slip behavior does not yet have clear design rules because of their hydrated nature and broad ability to tune the composition. This award will allow for highly-qualified students to examine the mechanisms of slip, and to combine their findings into more concrete design rules for these hydrogel surfaces. This requires them to draw from several disciplines including materials science, mechanical engineering, surface science, and even biomechanics. This work will allow for the recruitment and encouragement of underrepresented groups in engineering. The PI will participate in two ongoing summer camps for underrepresented K-12 students and will enlarge the curricula of these camps by bringing in women engineers from industry to lead educational events based on the science of lubrication. Specific interactions will be focused on highlighting the personal experiences of the industry leaders to encourage the camp participants to pursue STEM careers. The PI will also leverage large undergraduate course activities, in particular design experiences, to expose students to successful undergraduate and graduate research. The fundamental results are anticipated to promote scientific progress and advance the national health. In humans, cartilage layers provide both robust lubrication and mechanical damping, among chemical and biological functions. The mechanics of energy dissipation in hydrated soft surfaces, especially under contact and slip, have not been sorted out, and thus there is no way to currently engineer the lubrication behavior required for prosthetic devices which support load and control slip. This work examines reigning theories as to their ability to account for energy dissipation under slip, including fluid load support, viscoelastic relaxation, and fluid shear. Experiments on mechanical deformation and contact will prove or disprove the hallmarks of different mechanisms, such as the pressure-dependence on friction coefficient. The material composition will also be varied, and the results will be assembled into guiding design principles for soft hydrated surfaces. Complementary to the research goal of this work is the educational goal of increasing the diversity of STEM professionals in Illinois and the U.S by collaborating with industry on high school outreach activities and leveraging large undergraduate course activities for exposure to research.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.