Integrated 'on-chip' optical coherence tomography (OCT) system for point of care imaging diagnostics

研究背景：尼泊尔被列为发展援助委员会（DAC）名单上收入最低的国家之一，即使与亚洲其他国家相比，大多数措施也认为人口的总体健康状况很差。获得医疗保健的机会受到严重限制，特别是在农村地区，这无疑是普遍进步的一个限制因素。我们已经确定了尼泊尔境内一个具体的未满足的临床需求，这与这一提案呼吁完全一致;通过提供负担得起的即时成像诊断，可以提供帮助。在尼泊尔，慢性阻塞性肺疾病（COPD）的患病率非常高（高达43%），近年来这一直是尼泊尔的头号死亡原因（>9%）。据认为，这主要是由于室内空气质量差造成的，在地理和经济上都难以到达的农村地区，这种情况甚至更为严重。这在女性中尤其高，这可能在很大程度上归因于使用生物质燃料进行室内烹饪和加热的根深蒂固的文化。目的和目标：我们的目标是开发一种低成本的小型化、集成的基于芯片的光学相干断层扫描（OCT）的诊断工具，该工具将为获得这种临床成像技术可以对COPD诊断和治疗产生影响的复杂程度提供变革性变化。关键的进步将源于将商业OCT系统核心的光纤干涉仪转移到硅光子芯片上，这将通过制造可扩展性实现系统复杂性和成本降低。硅光子学非常适合这一点，因为它在大多数OCT系统的目标工作波长（1300 nm）下是透明的，并且所需的干涉仪组件现在都已被单独证明。这些亚微米光学器件的制造可以使用围绕电信行业建立的全球无源制造基础设施，以较低的成本和极高的公差进行大规模扩展。此外，这些组件中的许多组件现在也已在氮化硅（SiN）平台中实现，将功能向下扩展到可见光范围，这与某些生物医学成像机制特别相关。我们将通过波长缩放的通用光路设计与硅器件并行开发基于SiN的干涉仪作为概念验证。最后，我们将采取雄心勃勃的一步，开发一个完整的，无光纤芯片为基础的解决方案，通过混合集成的微型光源与硅/SiN为基础的interferometer.Potential的应用和好处：低复杂性，低成本，微型OCT系统的愿景纳入现有的支气管镜或导管为基础的医疗设备，可以使用沿着与商业上可用的数据采集硬件和分析软件在移动的平台是触手可及的。这样的系统可以提供对复杂的成像诊断工具的必要访问，该成像诊断工具可以取代基本的肺量计甚至基于纤维的支气管镜检查作为COPD早期诊断的金标准。它的最大好处首先将在我们的伙伴国家尼泊尔的偏远地区感受到，那里的疾病流行率很高，而且由于地理和经济原因，获得这种设施的机会有限。组织成像分辨率和速度的提高也有望从根本上帮助我们提高对COPD进展的理解。例如，所提出的OCT技术的开发和广泛采用将产生高质量的人群特异性数据集，供研究人员和临床医生使用。

The research context:Nepal is classified as one of the lowest income countries on the Development Assistance Committee (DAC) list and the general health of the population is considered to be poor by most measures, even in comparison with the rest of Asia. Access to healthcare is severely restricted, particularly in rural regions, which is undoubtedly a limiting factor to progress, generally. We have identified a specific unmet clinical need within Nepal that is fully aligned with this call for proposals; aided as it could be by the provision of affordable, point-of-care imaging diagnostics. There is an unusually high prevalence (up to 43%) of the population in Nepal suffering from chronic obstructive pulmonary disease (COPD) and this has been the number one cause of death (>9%) there in recent years. This is thought to arise principally as a result of poor indoor air quality, with the condition being even more acute in difficult to reach, both geographically and economically, rural regions. It is particularly high amongst women, which may be largely attributable to the deeply embedded culture of indoor cooking and heating with biomass fuelsAims and objectives:Our aim is to develop a low cost miniaturized, integrated chip-based optical coherence tomography (OCT) based diagnostic tool which will provide a transformative change to the level of sophistication that access to such clinical imaging technology can bring to bear on COPD diagnosis and therapy. The key advance will stem from transitioning the fibre based interferometer at the heart of commercial OCT systems onto the silicon photonics chip, which will enable system complexity and cost reductions through manufacturing scalability. Silicon photonics is aptly suited to this because it is transparent at the target operating wavelength (1300nm) of most OCT systems and the required interferometer components have now all been demonstrated in isolation. Manufacturing of these sub-micron optical devices can be massively scaled at lower cost and to extremely high tolerances using the global passive fabrication infrastructure that has been built up around the telecommunications industry. In addition, many of these components have now also been realised in the silicon nitride (SiN) platform, extending capabilities down towards the visible range, which is particularly relevant to certain biomedical imaging regimes. We will develop SiN based interferometers in parallel with the silicon devices through wavelength scaled common optical circuit designs as proof of concept. Finally, we will take the ambitious step of developing a complete, fibre-less chip based solution by hybrid integration of miniature optical sources with the silicon/SiN based interferometers.Potential applications and benefits:The vision of a low complexity, low cost, miniature OCT system incorporated within existing bronchoscopy or catheter based medical devices that could be used along with commercially available data acquisition hardware and analytical software on a mobile platform is within reach. Such a system can provide the necessary access to a sophisticated imaging diagnostic tool that could displace basic spirometry and even fibre based bronchoscopy as the gold standard for early diagnosis of COPD. Its greatest benefit will be felt, initially, within remote regions of our partner LMIC country, Nepal where a high prevalence of the disease is exemplified and where access to such facilities is limited by both geography and economy. Improvements in resolution and speed for tissue imaging can also be expected to help improve our understanding of COPD progression in a fundamental way. For example the development and widespread adoption of the proposed OCT technology would generate population specific datasets of high quality for use by researchers and clinicians.