An Embedded Cytometer for Autonomous Platforms

光合微生物——浮游植物——每年产生地球上大约50%的氧气和有机物质，并作为海洋食物网的基础。流式细胞仪是一种重要的海洋仪器，可以快速准确地测量单个浮游植物细胞的丰度、大小和荧光特性。例如，流式细胞术导致原绿球菌的发现，原绿球菌是地球上最丰富的光合生物。然而，在首次描述专门为测量海洋浮游植物而设计的流式细胞仪37年后，流式细胞仪的复杂性及其产生的多参数数据仍然是其向海洋领域仪器的普遍使用发展的障碍。PipeCyte是一种小型，低功率流式细胞仪，设计用于自主测量0.5-10微米直径的浮游植物，同时部署在自主海洋测量平台上。在第一个部署项目中，PipeCyte仪器将浸入深度达100米的水下，并与水面浮标相连。水面浮标是一种低成本的平台，从研究船上部署起来很简单。在这个项目中，几个浮标部署的PipeCyte仪器将被释放到开阔的海洋中，对不同深度的浮游植物群落进行测量。这些测量将提供一个前所未有的关于环境特征和沿水柱浮游植物群落之间关系的观点。先前开发的PipeCyte原型将通过重新设计和重新包装定制采集和控制电路来减少尺寸和功率需求。这个新的低于20瓦的PipeCyte V2将被安置在一个市售的压力外壳内。在实验室使用校准微球和培养的浮游植物对仪器进行校准后，将在普吉特海湾对浮式系留仪器进行初步现场测试。以前在R中开发的用于分析SeaFlow流式细胞仪数据的自动数据分析方法将被移植到基于PipeCyte Labview的控制软件中，以便将多参数流式细胞仪数据实时简化为浮游植物种群计数。这种简化的数据集连同GPS定位将通过卫星调制解调器传回船上和岸上。拟议的浮标部署仪器将由四个100 W-hr的锂电池供电，每次部署仪器的准点率约为50小时。最后的现场测试将在亚热带太平洋进行，以证明概念验证，在那里原绿球藻、聚球藻和小型真核浮游植物的实时计数将向船上广播。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The photosynthetic microbes – the phytoplankton – generate about 50% of the oxygen and organic matter produced on Earth each year and serve as the base of marine food webs. Flow cytometers are essential oceanographic instruments that rapidly and accurately measure the abundance, size and fluorescent characteristics of individual phytoplankton cells. For example, flow cytometry led to the discovery of Prochloroccocus, the most abundant photosynthetic organism on Earth. However, thirty-seven years after the first description of a flow cytometer designed specifically for the measurement of phytoplankton in the field, the complexity of flow cytometry, and the multi-parametric data it produces continues to be an obstacle to its evolution towards common use as an oceanographic field instrument. PipeCyte is a miniature, low-power flow cytometer instrument that was designed to perform autonomous measurements of 0.5-10 µm diameter phytoplankton while deployed on autonomous oceanographic measurement platforms. In this first deployment project, the PipeCyte instrument will be immersed at depths of up to 100 meters while tethered to a surface buoy. A surface buoy is a low-cost platform that is simple to deploy from a research vessel. In this project, several buoy deployed PipeCyte instruments will be released in the open ocean to perform measurements of the phytoplankton community at multiple depths. These measurements will provide an unprecedented view of the relation between environmental features and phytoplankton communities along the water column. A previously developed PipeCyte prototype will be iterated to reduce both size and power requirement through a redesign and repackaging of the custom acquisition and control circuitry. This new sub-20 watt PipeCyte V2 will be housed within a commercially available pressure housing. After instrument calibration in the lab using calibration microspheres and cultured phytoplankton, initial field testing of a float-tethered instrument will be performed in the Puget Sound. Automated data analysis methods previously developed in R for analysis of SeaFlow flow cytometer data will be ported to the PipeCyte Labview based control software so that the multi-parameter flow cytometer data can be reduced to phytoplankton population counts in realtime. This reduced data set along with GPS fix will be transmitted back to ship and shore by satellite modem. The proposed buoy-deployed instrument will be powered by four 100 W-hr lithium batteries to yield instrument on-time of approximately 50 hours per deployment. Final field testing to demonstrate proof-of-concept will occur in the sub-tropic Pacific Ocean where real-time counts of Prochlorococcus, Synechococcus and small eukaryotic phytoplankton will be broadcast to the ship.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.