The 2D particle tracking technique

We have developed an in-house MATLAB routines that are capable of tracking micrometer scale particles in that lie in the focal plane of the microscope. Here (a) shows a raw image as obtained by a CCD camera, (b) shows the tracked image with the circles corresponding to the locations of the particles that pass certain criteria. Altogether 61 particles have been identified in the image with the coordinates of the first 9 of them listed in the table to the right of the figure.

 

 

In addition to the routines to locate the particles currently the package includes programs that

 

• Connect the coordinates of the particles in successive time-lapse images thus allowing to find tracks of the particles.
• Estimate the density of the particles in the sample.
• Analyze the track of each individual particle to determine its average velocity, displacement, frequency with which the particle changes directions, etc.

 

While the 2D tracking software clearly does not provide as much information about trajectories of the particles as does the 3D version, this shortcoming is compensated by increases in processing speed as well as user-friendliness.