Rapid Manipulation of Magnetic Beads for Bio-Sensing Applications

Rapid manipulation of magnetic beads in themicro-scale regime is essential in many molecular biological applications. For example, a 2D or 3D manipulation of a single-bead in live cells is used toinvestigate molecular interactions inside cellularenvironment. To achieve high accuracy in the bead's manipulation, a common configuration of magnets, termed magnetic tweezers, which is highly focused, is used. Another application of magnetic beads isseparation of target molecules, such as proteins and nucleic acids, in biological assays. The target molecules are attached to magnetic beads and are held in place using magnetic forces. Then, the unbound molecules are washed away from the solution. In this in vitro application, the accuracy requirements of the magnetic forces are less tight. Major disadvantages of all washing-step applications are the complicated and expensive measures that are required to achieve proper washing. To reduce complexity in biological assays, alternative approaches of separation methods are investigated. In 2008, Danielli et al, developed a fluorescent-based assay, termed Magnetic Modulation Biosensing (MMB), which significantly improve the sensitivity of biological assays and eliminate the use of washing steps.

This study investigates processes of magnetic beads manipulation that are relevant for the MMB system and for other applications of that class. It mainly aims for two goals:

1. Understanding the influence of the solenoid physical parameters over the magnetic force magnitude it induces on paramagnetic beads, the beads manipulation profile between the pole tips, and the power consumption of the solenoids.

2. Designing optimized solenoids for the MMB system, and for other resembling applications as well.

The research includes theoretical analysis of simplified solenoid models, followed by a few COMSOL Multiphysics simulations for varied models that are quite complicated to study analytically. A few experiments of the MMB system are executed and presented as screen captures in order to justify the results achieved by the former research measures. 

B.Sc. research supervised by Dr. Amos Danielli