PipeCyte: An instrument to continuously and autonomously measure algal cells

微小的浮游植物每年产生的氧气约占地球上产生的氧气的一半。流式细胞仪是快速准确地测量单个浮游植物细胞的丰度、大小和荧光特性的基本海洋仪器。该项目的目标是开发一种小型化、低功耗、可在水下运行的连续流式细胞仪。目标部署平台是标准的船载水采样器(CTD玫瑰花环)，尽管设计特点最终将允许安装到各种其他海洋水下仪器中。这台名为PipeCyte的细胞仪将在CTD下降和上升过程中连续测量浮游植物细胞(0.5-20微米)的丰度、细胞大小和荧光特征，并将数据实时传输给CTD操作员。PipeCyte将从根本上改变目前基于CTD的叶绿素荧光测量方法所提供的海洋明亮部分的景象？除了叶绿素荧光峰外，操作员还将看到峰内不同类型的浮游植物的丰富程度。开发能够实时绘制微生物分布图的在建仪器对于了解海洋中的生物地球化学和生态过程是至关重要的。本文提出的仪器将提供一个前所未有的视角来了解环境特征与海洋浮游植物群落之间的关系。目前的水下流式细胞仪系统依赖于清洁水的供应来运行仪器，并且容易受到堵塞和生物污染的影响。PipeCyte依靠一种光学技术，可以对一股原始海水进行直接的细胞测量。主要的光学元件(透镜)浸入大直径的样品流体中，避免了与所有流动细胞仪中存在的小孔相关的常见堵塞和维护问题。这种浸泡的初级光学元件可以很容易地清洗或更换。该设计坚固、紧凑，在完全运行时将消耗15瓦或更少功率。该仪器的设计不需要比标准荧光计更多的维护。仪器的开发将分为三个阶段。首先，目前的PipeCyte原型将在另外两个原型中迭代，以通过不同的焦距来优化光学系统的灵敏度。其次，通过从目前的SeaFlow数据采集和控制电子设备过渡到基于微控制器的系统，将实现功率降低和小型化。这种设计路径将极大地降低仪器的功耗和尺寸，使其能够适应目标体积。最后，将针对基准的流式细胞仪系统进行实验室内验证，然后在海上进行现场测试。

Microscopic phytoplankton generate about half the oxygen produced on the planet each year. Flow cytometers are essential oceanographic instruments that rapidly and accurately measure the abundance, size and fluorescent characteristics of individual phytoplankton cells. The goal of this project is to develop a miniaturized, low-power, continuous flow cytometer that operates underwater. The targeted deployment platform is a standard ship-deployed water sampler (CTD rosette), although design features will ultimately allow installation into a variety of other oceanographic underwater instruments. Named PipeCyte, this cytometer will continuously measure abundance, cell size and fluorescence characteristics of phytoplankton cells (0.5-20 µm) during the down- and up-casts of the CTD and will transmit data in real time to CTD operators. PipeCyte will radically alter the view of the lit portion of the ocean currently afforded with CTD-based measures of chlorophyll fluorescence ? in addition to chlorophyll fluorescence peaks, operators will see the abundance of different types of phytoplankton within the peaks. Development of underway instrumentation that maps microbial distributions in real time is essential for understanding biogeochemical and ecological processes in the ocean. The instrument proposed here will provide an unprecedented view of the relation between environmental features and phytoplankton communities in the ocean.Current underwater flow cytometer systems depend on a supply of clean water for instrument operation and are vulnerable to clogging and biofouling. PipeCyte relies upon an optical technology that enables direct cytometric measurements on a flow of raw seawater. The primary optic (lens) is immersed in a large diameter flow of the sample fluid, sidestepping the usual clogging and maintenance issues associated with the small orifices present in all flow cytometers. This immersed primary optic can be easily cleaned or replaced. The design is robust, compact, and will consume 15 watts or less while under full operation. The instrument is designed to require no more maintenance than a standard fluorometer. Instrument development will be divided into three phases. First, the current PipeCyte prototype will be iterated in two more prototypes to optimize the sensitivity of the optical system by differing focal lengths. Second, power reduction and miniaturization will be achieved by transitioning from current SeaFlow data acquisition and control electronics to a microcontroller-based system. This design path will dramatically reduce the power consumption and dimensions of the instrument so it can fit within the target volume. Finally, in-lab validation against a benchmark flow cytometer system will be performed, followed by field-testing at sea.