Collaborative Research: Conformal and robust integrated infrared spectroscopic sensors

该项目旨在开创一种柔性光学传感器，这种传感器可以共形连接到人体皮肤上，用于持续的生理监测。传统的光学传感器通常笨重、成本高昂，而且涉及机械移动部件，影响了它们的坚固性，与之不同的是，拟议的努力将利用先进的集成光子技术将微型化的光学元件组合在柔性聚合物薄膜上。该传感器非常适合于血糖的连续监测。与依靠指尖刺血进行间歇性分析不同，该传感器将采用微创、纹身状的外形系数来连续监测体液中的葡萄糖浓度。集成的光子器件具有体积小、功耗低、坚固耐用、多路复用能力大以及通过这些器件中严格的光学限制实现强烈的光-分子/组织相互作用，因此独特地适合于体内传感、诊断、治疗和刺激功能。然而，传统的光子集成主要基于刚性半导体衬底，其机械刚性使得所产生的器件与软生物组织固有地不兼容。此外，尽管基于台式仪器的光学光谱学已经成为分析化学的黄金标准，但集成的光谱传感器在很大程度上仍未得到探索。该计划旨在通过结合灵活的光子集成和片上红外光谱传感技术来解决这些挑战，开创在保形塑料基板上的可穿戴光子传感系统。具体地说，用于持续血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。该计划的双重智能优点在于在共形衬底上采用非传统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一系列相互冲突的不同要求。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地集成到工艺流程中，并对其进行战略性塑造和定位，以利用其优势特性，同时绕过其限制。在光谱传感方面，光谱仪的小型化和集成化是将光谱传感器集成到芯片级平台上的主要技术障碍。该计划将开发一种新的传感器设计，显著提高系统简单性、坚固性、重复性和特异性，使可穿戴式传感应用成为可能，而不是缩小传统光谱仪的规模。科学研究将与课程开发、本科生培养以及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，该计划还将通过麻省理工学院开放式课程软件和edX倡议开发在线课程，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.