SCUID: A Carbon Nanotube Based Sensor for Measurement of Dissolved Gases in Water

这项研究的目的是开发一个能够测量海洋中感兴趣的溶解气体的现场海洋传感器平台，以便研究氧气最小区域的氮循环。到目前为止，这种类型的传感器还不存在，它是由两个成熟的系统结合而成的--一个是尖端技术的传感平台，另一个是经过验证的可潜水外壳。基于碳纳米管的气体传感器被认为是尖端技术，允许以相关的灵敏度检测范围广泛的环境和安全相关痕量气体。它们是低功率的，并提供了现场、实时、自动测量空间中的化学物质，用于火灾检测、燃料泄漏检测和健康监测系统。由于这些气体传感器的通用性、灵敏度和测量范围，世界各地的公司都在寻求集成这些传感器。近年来，大量生产这些传感器的初创企业已经形成，以应对高需求。虽然现在可以测量大气中的微量气体，如N2O、NO和DMS，但用于实时和现场测量海水中溶解气体的传感器仅限于二氧化碳、甲烷和硫化氢。其中几种与气候有关的气体已知是在低氧条件下产生的，例如开阔海洋中的氧气最低区，以及死亡区？在沿海海域。今天，像N2O和NO这样的溶解气体的高精度测量依赖于基于实验室的分析，如质谱分析和气相色谱。全球变暖是观测到的开放海洋氧气最小区域扩大的工作假说；层化增加减少了上层海洋的通风和通风。沿海地区缺氧的扩大与富营养化有关，富营养化与河流径流中过量的营养物质有关，这些营养物质来自于农田、田地和草坪上使用的化肥等来源。海洋生物在低氧条件下变得高度紧张，可能会发生戏剧性的生态影响，包括大量杀死鱼类和贝类以及有害的藻类水华。更持久的影响也会发生，因为幼鱼比成熟鱼更有可能受到影响，导致经济损失等不利的后续影响。迫切需要对缺氧区的气体循环有更深入的了解。测量与气候有关的痕量气体对于量化海洋源和汇以及了解它们对全球气候变化的影响是必要的。海洋界需要一种新的、小、低功率、实时的溶解气体传感器，它可以调节到不同的感兴趣气体，以便对特定感兴趣气体进行高空间分辨率采样。独立于平台的传感器可用于浮标、滑翔机、电导率-温度-深度传感器，以及用于公开水域和海岸溶解气体调查的自动水下航行器。这不仅将扩大传感器可以在现场检测到的溶解气体，还将支持海-气交换、温室气体和热液喷口等领域的科学发现、数据和模型。该传感芯片由单壁碳纳米管气体传感器组成。它由NASA艾姆斯研究中心提供，到目前为止已经被用来探测太空和地球上的几种气体。在这项研究中，传感芯片被训练成检测N2O和NO，这两种气体是海洋学界非常感兴趣的，但到目前为止还不可能在现场检测到。适合大海的可潜水房屋(至2000米)将由该领域的专家Pro-Oceanus提供。对N2O和NO的检出限分别为100 ppb和5 ppb。气体传感器和集成传感系统的实验室测试将在APL/UW进行。计划在本提案的第三年对胡德运河(华盛顿州)和墨西哥湾进行实地测试。如果成功，这些测试将产生无与伦比的N2O和无气体浓度的空间分辨率，并使我们能够得出迄今为止无法得出的关于海-气相互作用的结论。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This research aims at developing an in-situ oceanographic sensor platform that enables the measurement of dissolved gases of interest in the ocean in order to study the nitrogen cycle in oxygen minimum zones. This type of sensor does not exist to date and is accomplished by marrying two mature systems - a cutting edge technology sensing platform, and a proven submergible housing. Carbon nanotube-based gas sensors are considered cutting edge technology, allowing to detect a wide range of environmental and safety related trace gases at relevant sensitivities. They are low power, and have provided in-situ, real time, automated measurement of chemicals in space, for fire detection, for fuel leak detection, and as health monitoring system. Companies around the world are looking to integrate these gas sensors due to their versatility, sensitivity, and range of measurement. In recent years, start-ups manufacturing these sensors in large numbers have formed in response to the high demand. While it is possible today to measure trace gases such as N2O, NO, and DMS in the atmosphere, the sensors to measure dissolved gases in seawater real time and in situ are limited to only CO2, CH4, and H2S. Several of these climatically relevant gases are known to be produced under low oxygen conditions, such as the oxygen minimum zones in the open ocean, and ?deadzones? in the coastal ocean. Today highly precise measurement of dissolved gases like N2O and NO rely on laboratory-based analyses such as mass spectrometry and gas chromatography. Global warming is the working hypothesis for the observed expansion of open ocean Oxygen Minimum Zones; increased stratification reduces upper ocean ventilation and aeration. Expansion of hypoxia in the coastal zone is linked to eutrophication associated with excess nutrients in river runoff, from sources such as chemical fertilizers applied to farms, fields, and lawns. Marine life becomes highly stressed under hypoxic conditions, and dramatic ecological impacts can occur, including massive kills of fish and shellfish and harmful algae blooms. Longer lasting impacts also occur since juvenile fish are more likely to be affected than mature fish, resulting in detrimental follow-on effects such as economic losses. There is a critical need for a deeper understanding of gas cycling in hypoxic zones. Measurement of climatically relevant trace gases are necessary to quantify ocean sources and sinks, and to understand their impact on global climate change. The oceanographic community needs a new, small, low-power, real time dissolved gas sensor that can be tuned to different gases of interest to allow high spatial resolution sampling for specific gases of interest. A platform independent sensor can be used on floats, gliders, conductivity-temperature-depth sensors, and automated underwater vehicles for open water and coastal surveys of dissolved gases. This will not only expand the dissolved gases that a sensor can detected in situ, but bolster scientific discovery, data, and models in areas such as sea-air exchange, greenhouse gases, and hydrothermal vents. The sensing chip consists of a single wall carbon nanotube gas sensor. It is provided by NASA Ames Research Center and has been used to detect several gases in space and on earth to date. For this research, the sensing chip is trained to detect N2O and NO, two gases that are of great interest to the oceanographic community but have not been possible to detect in situ to date. The sea-worthy, submergible housing (to 2000m) will be provided by Pro-Oceanus, an expert in this field. Detection limits aimed for are 100ppb and 5ppb, for N2O and NO respectively. Laboratory testing of the gas sensor and integrated sensing system will take place at APL/UW. Field tests to Hood Canal WA), and the Gulf of Mexico are planned in year 3 of this proposal. If successful, these tests will yield unparalleled spatial resolution of N2O and NO gas concentrations, and allow us to draw conclusions about air-sea interaction that have not been possible to date.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.