Machine vision for microfluidic applications

Image processing is widely growing as a useful tool in biosensing applications. It can be used to convert any camera/microscope into an optical sensor with wide range of capabilities such as monitoring completion of colorimetric reactions, differentiating and counting of cells, and tracking motile cells/organisms. However, implementation of image processing in Lab-on-Chip devices is still challenging for biology researchers with little expertise in this field. We developed a multi-purpose real-time image processing platform for tracking and analyzing objects inside lab-on-chip devices and for automating many microfluidic applications. Our LabVIEW-based image processing platform, which can be downloaded here (LabView License is required), enables non-experts in image processing to easily assemble their image processing pipeline based on the intended application and imaging system being used (fluorescence, phase contrast, etc.). The program was designed for plug and play interfacing with a wide range of imaging devices including USB microscopes, high-speed cameras and smartphone cameras. Moreover, to achieve portability, the program can be loaded on myRIO, a portable pocket size fully functional LabVIEW platform, to perform all program capabilities outside the lab without the need for a PC. Furthermore, our platform uses the inherent control capabilities of LabVIEW for real-time control of application parameters.

You can check the videos below to see some of the capabilities of our program.

Identifying droplets encapsulating cells in a microchannel. Droplets containing cells have higher average pixel intensity compared to empty droplets.

Original video was published as a supplementary material with the following article:

J. F. Edd, D. Di Carlo, K. J. Humphry, S. Köster, D. Irimia, D. A. Weitz and M. Toner, Controlled encapsulation of single-cells into monodisperse picolitre drops, Lab Chip, 2008, 8, 1262-1264.

Detecting detect droplets as they flow inside a microchannel and calculate their area. Original video was published as a supplementary material with the following article:

Wang, W., Yang, C., Cui, X.Q. et al. Microfluid Nanofluid (2010) 9: 1175.

Uploading our code on myRio portable LabView platform and using to detect merging of two droplets on a digital microfluidic device. Droplets were detected and their area before and after merging was sent over WiFi to be displayed on a smartphone.

Studying sperm motion inside microchannels

Until now, the mechanism of sperm navigation inside the female reproductive tracts to reach the oocyte is still not confirmed. Although, chemotaxis and thermotaxis have been suggested as possible mechanisms, the former is though to be more prevalent in marine species whereas the latter have been dismissed by some recent studies. Very recently, Rheotaxis, which is sperm cell tendency to swim against the flow, has been suggested as a possible mechanism for directing sperm cells to the oocyte when they swim against the fluid secreted in the female reproductive system after coitus. In this project we characterize rheotaxis of bull sperm using microfluidics.

To learn more about this project, read our recent paper in Integrative Biology: Characterization of Rheotaxis of Bull Sperm Using microfluidics.

As part of this project, we have developed a new Computer Assisted Sperm Analysis (CASA) Plugin for analyzing sperm in microfluidic environments using Image-J. This plugin improves on a previously reported CASA plugin for easier user interaction, better accuracy, and added functionality in microfluidics.

You can learn more about our newly developed CASA plugin in our recent paper in Theriogenology: Development of Computer Assisted Sperm Analysis (CASA) Plugin for analyzing sperm motion in microfluidic environments using Image-J. You can download our plugin to use it in your own projects here. You can also check the Audioslides of our Theriogenology paper below:

The CASA plugin we developed is currently being used in some labs in Canada, India, Irelan, Brazil, and Japan. Check the map below for exact location of these laboratories.

Building a microfluidic chip to determine mechanical properties of biological cells

Mechanical properties of biological cells bear a significant relationship with the health state of the cell. Some diseases increase mechanical stiffness of cells as in the case of Malaria with red blood cells, whereas others decrease cell stiffness as in many reported cancer types. The aim of this project is to build a chip that measures mechanical stiffness of different cells to use it as a biomarker for different diseases.

Modeling droplet actuation in digital microfluidics

Electrodynamic forces induced on droplets in digital microfluidics are dependent on many factors such as electrical properties of the liquid being manipulated, electrode shape, actuation frequency, and device geometrical parameters. By simulating droplet actuation numerically, the effect of liquid properties and actuation frequency on electrodynamic forces generated on droplets and on droplet motion will be understood, which should enable more efficient device designs based on the intended application.

Studying contact angle saturation in electrowetting

When the potential of a sessile droplet sitting on a hydrophobic surface is biased relative to the electrode beneath the droplet, the electrodynamic forces generated on the droplet spread it on the surface which reduces its contact angle. This electrically-induced wetting, called Electrowetting, has extensive applications in optics such as variable focal length lenses and flexible displays. The aim of this project is to use energy modeling to find an explanation for the contact angle saturation phenomenon in electrowetting where the droplet contact angle ceases to decrease at a certain voltage contrary to the predictions o the famous Young-Lippmann equation.

You can check the new model we developed in our recent paper in Biomicrofluidics: Repulsion Based Model for Contact Angle Saturation.

Low cost digital microfluidics for exploratory research and educational purposes

In this project we target spreading digital microfluidics technology into the academic community for exploratory research and educational purposes by integrating rapidly prototyped devices with a portable and inexpensive setup to generate and control the high potentials required for droplet manipulation. We believe such combination will encourage researchers with non-engineering backgrounds, in Egypt and worldwide, to test digital microfluidics as a useful tool in their respective fields. Such low cost and accessible adaptation should promote the technology and generate novel applications.