A computational framework for particle and whole cell tracking applied to a real biological dataset.

Cell tracking is becoming increasingly important in cell biology as it provides a valuable tool for analysing experimental data and hence furthering our understanding of dynamic cellular phenomena. The advent of high-throughput, high-resolution microscopy and imaging techniques means that a wealth of large data is routinely generated in many laboratories. Due to the sheer magnitude of the data involved manual tracking is often cumbersome and the development of computer algorithms for automated cell tracking is thus highly desirable. In this work, we describe two approaches for automated cell tracking. Firstly, we consider particle tracking. We propose a few segmentation techniques for the detection of cells migrating in a non-uniform background, centroids of the segmented cells are then calculated and linked from frame to frame via a nearest-neighbour approach. Secondly, we consider the problem of whole cell tracking in which one wishes to reconstruct in time whole cell morphologies. Our approach is based on fitting a mathematical model to the experimental imaging data with the goal being that the physics encoded in the model is reflected in the reconstructed data. The resulting mathematical problem involves the optimal control of a phase-field formulation of a geometric evolution law. Efficient approximation of this challenging optimal control problem is achieved via advanced numerical methods for the solution of semilinear parabolic partial differential equations (PDEs) coupled with parallelisation and adaptive resolution techniques. Along with a detailed description of our algorithms, a number of simulation results are reported on. We focus on illustrating the effectivity of our approaches by applying the algorithms to the tracking of migrating cells in a dataset which reflects many of the challenges typically encountered in microscopy data.

Nano- and pico-dispensing of fluids on planar substrates using SAW.

The increasing interest in miniaturization of biological and chemical experiments or assays demands precise metering of the smallest amounts of reagents, e.g., on a planar substrate. Very sophisticated spotting systems can nowadays produce arrays of many thousands of different substances on an area of a few square inches. Such micro arrays and the technology behind them have become an important tool in genomic expression assays, proteomic applications, and even in the field of combinatoric chemistry. We present a technique to dispense the smallest amounts of fluids in the form of either simple spots or more complicated microarrays, where we use surface acoustic waves in combination with a predetermined surface chemistry. In addition to a detailed description of the technique, several examples of applications are presented.