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

以高度敏感的方式确定和测量自然产生或排放的气体和金属种类的数量，对确保公众的福利至关重要；急救人员、军事人员和高风险工作场所雇员的安全；以及评估气体和金属影响的能力，这对可持续的全球环境至关重要。该项目开发了一种未开发的化学传感方法，该方法基于光束在遇到微量气体或金属离子时被移动的位置。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在纳米大小的金属层表面反射的特性，这些金属层表面涂有环保的离子液体薄膜。该项目旨在提供前所未有的、低成本的环境中大气气体和金属离子监测，在各种条件和地点。使用这种新方法的小型化传感器的大规模生产有可能被各行各业的人们广泛使用。本研究的多学科合作性质影响了使用团队合作方法训练的研究生和本科生的教育。为了鼓励来自弱势群体的高中生获得受教育的机会，东克利夫兰学区的学生实习生通过联合举办的讲习班接受培训。研讨会有讲座和实验室组成部分，重点关注工程与科学之间的跨学科研究如何解决当前和迫切的社会需求。在化学学部化学测量和成像项目的支持下，凯斯西储大学的B. Gurkan、Hinczweski、Strangi和U. Gurkan教授正在致力于开发一种新的“通用”方法来检测气体和金属离子。该研究的三个具体目标是：(1)设计一种光子纳米结构，以显著增强入射激光束的Goos-Hanchen （GH）位移，从而实现对局部介电常数变化的超灵敏检测；(2)了解纳米结构上方离子液体层在二氧化碳、金属盐等溶质存在下的折射率变化；(3)评价多路接口的灵敏度和响应性。传感机制是基于GH位移，其中激光束内部反射在棱镜表面沿表面位移。GH位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。光子纳米结构放大了GH位移的幅度，使其易于检测。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纳米加工计算设计和创建的。为了抑制干扰，在顶层使用不同的离子液体，在暴露于目标分析物时可调整介电常数变化，从而采用多路复用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.