Lagrangian 3D tracking of fluorescent microscopic objects in motion

TL;DR

This paper presents a real-time 3D tracking system for fluorescent micro-objects in micro-fluidic devices, combining mechanical stage control and refocusing techniques to obtain detailed trajectories of motile microorganisms.

Contribution

The authors developed a novel 3D Lagrangian tracking device integrating real-time image processing, mechanical stage movement, and refocusing to track fluorescent objects in micro-fluidic environments.

Findings

Achieved 3D tracking at several tenths of Hertz frequency.

Successfully tracked motile micro-organisms in micro-fluidic devices.

System effectively maintains focus and position of moving objects.

Abstract

We describe the development of a tracking device, mounted on an epi-fluorescent inverted microscope, suited to obtain time resolved 3D Lagrangian tracks of fluorescent passive or active micro-objects in micro-fluidic devices. The system is based on real-time image processing, determining the displacement of a x,y mechanical stage to keep the chosen object at a fixed position in the observation frame. The z displacement is based on the refocusing of the fluorescent object determining the displacement of a piezo mover keeping the moving object in focus. Track coordinates of the object with respect to the micro-fluidic device, as well as images of the object are obtained at a frequency of several tenths of Hertz. This device is particularly well adapted to obtain trajectories of motile micro-organisms in micro-fluidic devices with or without flow.