Collaborative Research: Conformal and robust integrated infrared spectroscopic sensors

该项目旨在开发一种柔性光学传感器，这种传感器可以以保形形式附着在人体皮肤上，用于连续的生理监测。传统的光学传感器通常体积庞大，成本高昂，并且涉及机械运动部件，从而损害了其稳健性。与传统的光学传感器不同，该项目将利用先进的集成光子技术，在柔性聚合物膜上结合小型化的光学元件。该传感器是连续血糖监测的理想选择。这种传感器将采用微创的、类似纹身的形式，以连续监测体液中的葡萄糖浓度，而不是依靠刺破手指来抽血进行间歇性分析。集成光子器件在体内传感、诊断、治疗和刺激功能方面具有独特的优势，因为它们具有小尺寸、低功耗、鲁棒性、大复用容量，以及通过这些器件中的紧密光约束实现强光分子/组织相互作用。然而，传统的光子集成主要基于刚性半导体衬底，其机械刚度使得所得到的器件本质上与柔软的生物组织不相容。此外，虽然基于台式仪器的光谱学已成为分析化学的黄金标准，但集成光谱传感器在很大程度上仍未被探索。该项目旨在通过结合柔性光子集成和片上红外光谱传感技术来解决挑战，开创一种可穿戴的共形塑料基板光子传感系统。具体来说，一种用于连续血糖监测的微创表皮传感器将被证明是一个概念验证模型平台。该计划的双重智力优势在于在保形衬底上采用非常规的多材料光子集成方法以及创新的光谱传感器设计。共形衬底上的光子集成对组成材料的机械和光学特性提出了各种经常相互冲突的要求。在这个项目中，将在柔性基板上追求一种变革性的多材料、多功能集成方法，其中每种材料都无缝集成到工艺流程中，并战略性地形成和定位，以便利用其优势特性，同时规避其局限性。在光谱传感方面，光谱仪的小型化和集成化是实现光谱传感器集成到芯片级平台的主要技术障碍。该项目将开发一种新颖的传感器设计，大大提高系统的简单性、坚固性、可重复性和特异性，而不是缩小传统光谱仪的尺寸，使可穿戴式传感应用成为可能。科学研究将与课程开发、本科生培训和光学教育实践模块的开发紧密结合。除了加强两所学院的课堂教育外，该项目还将通过麻省理工学院开放课程和edX计划开发在线课程，促进知识的免费共享和传播。

The program aims to pioneer a flexible optical sensor which can be conformally attached to human skin for continuous physiological monitoring. Unlike conventional optical sensors which are often bulky, costly, and involve mechanical moving parts which compromise their robustness, the proposed effort will leverage advanced integrated photonic technologies to combine miniaturized optical components on a flexible polymer membrane. The proposed sensor is ideally suited for continuous glucose monitoring. Instead of relying on fingertip pricking with lancets to draw blood for intermittent analysis, the proposed sensor will assume a minimally invasive, tattoo-like form factor for continuous monitoring of glucose concentration in body fluids.Integrated photonic devices are uniquely poised for in-vivo sensing, diagnostics, therapeutics, and stimulation functions, given their small form factor, low power consumption, robustness, large multiplexing capacity, as well as strong light-molecule/tissue interactions enabled by tight optical confinement in these devices. Nevertheless, conventional photonic integration is predominantly based on rigid semiconductor substrates, and their mechanical stiffness makes the resulting devices inherently incompatible with soft biological tissues. Further, while optical spectroscopy based on bench top instruments has become the gold standard in analytical chemistry, integrated spectroscopic sensors remain largely unexplored. This program aims to resolve the challenges by combining flexible photonic integration and on-chip infrared spectroscopic sensing technologies to pioneer a wearable photonic sensing system on conformal plastic substrates. Specifically, a minimally invasive epidermal sensor for continuous glucose monitoring will be demonstrated as a proof-of-concept model platform. The two-fold intellectual merits of the program lie in the unconventional multi-material photonic integration approach on conformal substrates as well as the innovative spectroscopic sensor design. Photonic integration on conformal substrates poses a diverse set of often mutually conflicting requirements on the mechanical and optical properties of constituent materials. In this program, a transformative multi-material, multi-functional integration approach on flexible substrates will be pursued where each material is seamlessly integrated into the process flow and strategically shaped and positioned so as to make use of its advantageous properties while circumventing its limitations. On the spectroscopic sensing front, miniaturization and integration of spectrometers present a major technical barrier towards spectroscopic sensor integration onto chip-scale platforms. Rather than downscaling traditional spectrometers, the program will develop a novel sensor design with significantly improved system simplicity, ruggedness, reproducibility and specificity, enabling wearable sensing applications. The scientific research will be tightly integrated with curriculum development, undergraduate student training, and development of hands-on modules for optics education. In addition to augmenting classroom education at both institutes, the program will promote the free sharing and distribution of knowledge by developing online courses through the MIT OpenCourseWare and edX initiatives.