Instrument Development: Multiplex Sensory Interfaces Between Photonic Nanostructures and Thin Film Ionic Liquids

以高度敏感的方式识别和测量自然产生或排放的气体和金属物种的数量，对于确保公众的福利、第一反应人员、军事人员和高风险工作场所员工的安全以及评估对可持续全球环境至关重要的气体和金属的影响至关重要。该项目开发了一种尚未探索的化学传感方法，该方法基于遇到气体或金属离子的微小水平时光束的位置被移动。一个由化学家、物理学家和工程师组成的团队正在利用光波的特性，当它们从涂有环保离子液体薄膜的纳米级金属层表面反弹时。该项目旨在提供前所未有的、低成本的大气气体和环境中金属离子的监测，在各种条件和地点下。使用这种新方法的微型传感器的大规模生产，有可能让各行各业的人们广泛使用这种传感器。这项研究的多学科合作性质影响了使用团队合作方法进行培训的研究生和本科生的教育。为了鼓励来自代表性不足群体的高中生有接受教育的机会，来自东克利夫兰学区的学生实习生通过联合举办的研讨会进行培训。研讨会有讲座和实验室部分，重点是工程和科学之间的跨学科研究如何满足当前和迫切的社会需求。在化学系化学测量和成像计划的支持下，凯斯西储大学的B.Gurkan、Hinczweski、Strangi和U Gurkan教授正在研究一种新的用于气体和金属离子检测的“通用”方法的开发。这项研究的三个具体目标是：(1)设计一种光子纳米结构，显著增强入射激光的Goos-Hancen(GH)位移，从而能够超灵敏地检测局部介电常数变化；(2)了解纳米结构上方离子液体层在二氧化碳和金属盐等溶质存在时的折射率变化；以及(3)评估复合界面的灵敏度和响应性。该传感机制基于GH位移，其中在棱镜表面内反射的激光束沿棱镜表面移位。GH漂移的大小取决于棱镜顶部材料的结构和折射率，包括离子液体层。这种光子纳米结构放大了生长激素移位的幅度，因此很容易被检测到。由具有不同层次排列和结构的交替电介质层或金属层组成的光子纳米结构是通过计算设计和通过纳米制造来创建的。为了抑制干扰，在顶层使用了不同的离子液体，在接触目标分析物时具有可定制的介电常数变化。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Identifying and measuring the amount of naturally occurring or emitted gases and metal species in a highly sensitive way is critical for ensuring the welfare of the public; the safety of first responders, military personnel, and employees in high-risk workplace settings; and the capability to assess the impact of gases and metals that are key to a sustainable global environment. This project develops an unexplored chemical sensing method that is based on the position of light beams being shifted when minute levels of a gas or metal ion are encountered. A team of chemists, physicists, and engineers is taking advantage of the properties of light waves when they bounce off the surface of nanometer-sized metal layers coated with thin films of environmentally friendly ionic liquids. The project aims to offer unprecedented, low-cost monitoring of atmospheric gases and metal ions in the environment, under a wide variety of conditions and locations. Mass production of miniaturized sensors that use the new method has the potential for widespread use of the sensors by people from many walks of life. The multidisciplinary collaborative nature of this research impacts the education of graduate and undergraduate students who are trained using a teamwork approach. To encourage educational opportunities for high school students from underrepresented groups, student interns from the East Cleveland School District are trained through a jointly organized workshop. The workshop has lecture and laboratory components and focuses on how the cross-disciplinary research between engineering and science can address current and pressing needs in society.With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professors B. Gurkan, Hinczweski, Strangi, and U. Gurkan at Case Western Reserve University are addressing development of a new "universal" method for the detection of gases and metal ions. The three specific aims of the study are: (1) engineering a photonic nanostructure to dramatically enhance the Goos-Hanchen (GH) displacement of an incident laser beam, allowing for ultrasensitive detection of local permittivity changes; (2) understanding of the refractive index changes of the ionic liquid layer above the nanostructure, in the presence of solutes such as carbon dioxide and metal salts; and (3) evaluating sensitivity and responsiveness of the multiplex interface. The sensing mechanism is based on GH displacement, where a laser beam internally reflected at a prism surface is displaced along the surface. The size of the GH shift depends on the structure and refractive indices of the materials on top of the prism, including the ionic liquid layer. The photonic nanostructure amplifies the magnitude of the GH shift so that it becomes easily detectable. The photonic nanostructure consisting of alternating dielectric or metal layers with different hierarchical arrangements and architectures are computationally designed and created by nanofabrication. To suppress interferences, multiplexing is employed by the use of different ionic liquids on the top layer with tailorable permittivity changes upon exposure to target analytes.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.