Lab-in-a-Fiber Optofluidic Platform: In-Situ Assembly and Response of Layer-by-Layer Polyelectrolyte Films in Confined Geometry

该项目由材料研究部(DMR)的电子与光子材料计划(EPM)和电子、通信和网络系统(ECCS)的电子、光子学和磁性器件计划(EPMD)共同资助。技术描述：本项目是将折射率导引光子晶体光纤中的长周期光栅结构与功能聚电解质薄膜的逐层(LBL)组装集成在一起的理论和实验研究。该集成系统由于其高折射率灵敏度和在轴向对准的包层空气通道中实现分子/纳米级功能化的可行性，代表了一个光纤实验室光流体平台。这项研究的目的是为了深入了解LBL在光纤中生长的不同特征，并探索LBL薄膜对受限几何形状刺激的响应，以论证集成方案用于光流控传感器的可行性。项目活动包括：(1)模拟各种光纤实验室配置下的模式耦合，以确定具有尽可能高折射率灵敏度的最佳平台；(2)以模拟为指导，在指定的谐振波长实现模式耦合；(3)沉积具有不同链交换倾向的LBL聚电解质，同时原位测量共振波长的移动量；以及(4)在光纤实验室平台上评估通过LBL构建的聚酸基水凝胶的pH响应。该项目的中心目标是(1)建立一种新型的光纤中光流体学来原位研究LBL的沉积；(2)为受限几何中LBL的沉积和响应提供重要的见解；以及(3)为探索光纤中的光流体传感建立知识基础。非技术描述：本项目的研究部分是研究一种特殊类型的光纤--具有长周期光栅结构的光子晶体光纤中的逐层薄膜生长，并研究该薄膜对受限几何条件下刺激的响应。该项目的成功预计将为基础和应用研究界带来一个变革性的光纤实验室光流体刺激响应平台，用于科学探索和技术应用。从教育角度来看，该项目面向博士生、本科生以及高中生。研究成果的传播是通过各种渠道实现的，包括同行评议出版物、会议报告、网络张贴和课堂案例研究。

This project is jointly funded by the Electronic and Photonic Materials Program (EPM) in the Division of Materials Research (DMR) and the Electronics, Photonics, and Magnetic Devices Program (EPMD) in the Division of Electrical, Communications and Cyber Systems (ECCS).Technical Description: This project is a theoretical and experimental investigation to integrate layer-by-layer (LbL) assembly of functional polyelectrolyte thin films with a long-period grating structure inscribed in index-guided photonic crystal fiber. The integrated system represents a lab-in-a-fiber optofluidics platform by virtue of its high refractive index sensitivity and the feasibility for molecular/nanoscale functionalization in axially aligned cladding air channels. The research is designed to gain fundamental insights into distinct features of LbL growth in fiber and to probe the response of the LbL film to stimuli in confined geometry in order to demonstrate the feasibility of the integrated scheme for optofluidic sensors. Project activities entail (1) simulation of mode coupling in various lab-in-a-fiber configurations to determine optimal platform with the highest possible index sensitivity; (2) inscription of the grating structure with the simulation as a guide to realize mode coupling at prescribed resonant wavelengths; (3) deposition of LbL polyelectrolytes with different propensity to chain exchange with a multitude of parameters while measuring the shift in resonance wavelength in situ; and (4) evaluation of the pH response of polyacid-based hydrogels constructed via LbL in the lab-in-a-fiber platform. The central goals of this project are to (1) establish a novel lab-in-a-fiber optofluidics to study LbL deposition in situ; (2) provide important insights into the distinct features of LbL deposition and response in confined geometry; and (3) build a knowledge foundation for the exploration of lab-in-a-fiber optofluidic sensing.Non-technical Description: The research component of this project is to investigate layer-by-layer thin-film growth inside a special type of optical fiber, photonic crystal fiber with long-period grating structure, and to study the response of the thin film to stimuli in confined geometry. The success of the project is expected to bring to basic and applied research community and potentially the market place a transformative lab-in-a-fiber optofluidic stimuli-responsive platform for scientific exploration and technological applications. From educational perspective, this project engages doctoral students, undergraduate students, as well as high-school students. Dissemination of research results is achieved via various channels, including peer-reviewed publications, conference presentations, web posting, and case studies in classrooms.