Collaborative Research: Conformal and robust integrated infrared spectroscopic sensors

该计划旨在开创一种灵活的光学传感器，可以保形地附着在人体皮肤上进行连续的生理监测。与传统的光学传感器不同，传统的光学传感器通常体积庞大，成本高昂，并且涉及损害其鲁棒性的机械移动部件，所提出的努力将利用先进的集成光子技术将联合收割机小型化的光学部件组合在柔性聚合物膜上。所提出的传感器非常适合连续葡萄糖监测。该传感器将采用微创、纹身式的外形，用于连续监测体液中的葡萄糖浓度，而不是依靠指尖刺血进行间歇性分析。集成光子器件具有外形小、功耗低、鲁棒性强、多路复用容量大、以及通过在这些装置中的紧密光学限制而实现的强的光分子/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，并且它们的机械刚度使得所得到的器件与软生物组织固有地不相容。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开发。该计划旨在通过将灵活的光子集成和片上红外光谱传感技术相结合来解决这些挑战，从而在保形塑料基板上开创可穿戴光子传感系统。具体而言，用于连续葡萄糖监测的微创表皮传感器将作为概念验证模型平台进行演示。该计划的双重智力优势在于共形衬底上的非常规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性质提出了一组经常相互冲突的要求。在该计划中，将在柔性基板上追求变革性的多材料，多功能集成方法，其中每种材料都无缝集成到工艺流程中，并进行战略性的成形和定位，以便利用其有利特性，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是将光谱传感器集成到芯片级平台上的主要技术障碍。该计划不是缩小传统光谱仪的规模，而是开发一种新型传感器设计，显著提高系统的简单性，耐用性，再现性和特异性，从而实现可穿戴传感应用。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。除了加强这两个研究所的课堂教育外，该计划还将通过麻省理工学院的开放式课程和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.