Droplet morphometry and velocimetry (DMV): a video processing software for time-resolved, label-free tracking of droplet parameters
Droplet morphometry and velocimetry (DMV): a video processing software for time-resolved, label-free tracking of droplet parameters
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DOI：
10.1039/c3lc50074h
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发表时间：
2013-01-01
期刊：
影响因子：
6.1
通讯作者：
Basu, Amar S.
中科院分区：
文献类型：
--
作者：
Basu, Amar S.
液滴微流体中的新兴测定需要测量诸如液滴尺寸、速度、轨迹、形状变形、荧光强度等参数。虽然微粒子图像测速（mPIV）和相关技术适用于使用示踪粒子测量流动，但是不存在用于以单个实体的粒度跟踪液滴的工具。本文介绍了一种用于时间分辨液滴分析的数字视频处理软件--液滴形态测量和速度测量（DMV）。通过一系列图像处理步骤识别液滴，这些步骤对透明、半透明、荧光或不透明液滴进行操作。该方法包括背景图像生成、背景差分、边缘检测、小目标去除、形态学闭合与填充、形状判别等步骤。帧相关步骤然后经由最近邻搜索将跨越多个帧的液滴与用户定义的匹配标准链接。每个步骤都可以单独调整，以实现最大的兼容性。对于发现的每个液滴，DMV提供20个不同参数的时间历史，包括轨迹、速度、面积、尺寸、形状变形、方向、最近邻间距和像素统计。数据可以通过散点图、直方图和表格以单个液滴的粒度或通过在群体上累积的统计来报告。我们提出了来自工业和学术实验室的几个案例研究，包括测量1）液滴发生器中的尺寸分布和流动扰动，2）液滴分离/合并装置中的尺寸分布和混合速率，3）单细胞封装装置的效率，4）电润湿操作中的位置跟踪，5）连续液滴稀释器中的化学浓度，6）张力电泳装置的液滴分选效率，7）蛇形通道中非球形塞的塞长度和取向，以及8）再注射系统中>250个液滴的高通量跟踪。性能指标表明，当视频分辨率>300像素/液滴时，可获得最高的准确度和精度。分析时间随视频分辨率成比例增加。该软件的当前版本提供了2-30 fps的吞吐量，这表明了真实的时间分析的潜力。
Emerging assays in droplet microfluidics require the measurement of parameters such as drop size, velocity, trajectory, shape deformation, fluorescence intensity, and others. While micro particle image velocimetry (mPIV) and related techniques are suitable for measuring flow using tracer particles, no tool exists for tracking droplets at the granularity of a single entity. This paper presents droplet morphometry and velocimetry (DMV), a digital video processing software for time-resolved droplet analysis. Droplets are identified through a series of image processing steps which operate on transparent, translucent, fluorescent, or opaque droplets. The steps include background image generation, background subtraction, edge detection, small object removal, morphological close and fill, and shape discrimination. A frame correlation step then links droplets spanning multiple frames via a nearest neighbor search with user-defined matching criteria. Each step can be individually tuned for maximum compatibility. For each droplet found, DMV provides a time-history of 20 different parameters, including trajectory, velocity, area, dimensions, shape deformation, orientation, nearest neighbour spacing, and pixel statistics. The data can be reported via scatter plots, histograms, and tables at the granularity of individual droplets or by statistics accrued over the population. We present several case studies from industry and academic labs, including the measurement of 1) size distributions and flow perturbations in a drop generator, 2) size distributions and mixing rates in drop splitting/merging devices, 3) efficiency of single cell encapsulation devices, 4) position tracking in electrowetting operations, 5) chemical concentrations in a serial drop dilutor, 6) drop sorting efficiency of a tensiophoresis device, 7) plug length and orientation of nonspherical plugs in a serpentine channel, and 8) high throughput tracking of >250 drops in a reinjection system. Performance metrics show that highest accuracy and precision is obtained when the video resolution is >300 pixels per drop. Analysis time increases proportionally with video resolution. The current version of the software provides throughputs of 2-30 fps, suggesting the potential for real time analysis.