Droplet morphometry and velocimetry (DMV): a video processing software for time-resolved, label-free tracking of droplet parameters
- 8 March 2013
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Lab on a Chip
- Vol. 13 (10), 1892-1901
- https://doi.org/10.1039/c3lc50074h
Abstract
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 (μPIV) 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.Keywords
This publication has 21 references indexed in Scilit:
- Droplet sorting based on the number of encapsulated particles using a solenoid valveLab on a Chip, 2013
- Droplet microfluidics for high-throughput biological assaysLab on a Chip, 2012
- Droplet size based separation by deterministic lateral displacement—separating droplets by cell-induced shrinkingLab on a Chip, 2011
- Microdroplets in Microfluidics: An Evolving Platform for Discoveries in Chemistry and BiologyAngewandte Chemie-International Edition, 2010
- Ultrahigh-throughput screening in drop-based microfluidics for directed evolutionProceedings of the National Academy of Sciences of the United States of America, 2010
- Applications of Holography in Fluid Mechanics and Particle DynamicsAnnual Review of Fluid Mechanics, 2010
- Droplet microfluidicsLab on a Chip, 2008
- Reactions in Droplets in Microfluidic ChannelsAngewandte Chemie-International Edition, 2006
- Digital holographic microscope for measuring three-dimensional particle distributions and motionsApplied Optics, 2006
- A particle image velocimetry system for microfluidicsExperiments in Fluids, 1998