Magneto-active mixing and catching for microfluidic biosensors

A biosensor is an instrument that can rapidly measure the concentration of biological molecules in a fluid such as blood or saliva. A successful example of a commercial molecular sensor is the glucose sensor. This sensor requires a sample of only 1 µl that is obtained by a painless finger prick. Sampling and analysis are easy to perform, reliable, rapid and cost-effective.

Unfortunately, many applications require much higher detection sensitivity, for example, when proteins, hormones, drugs or nucleic acids have to be detected. So the challenge is to develop biosensors that are as rapid, small and reliable as the glucose sensor, but can detect substances at much lower concentrations. The drive to realize such sensors is leading to the development of lab-on-a-chip systems. In such systems, mass transport is dominated by diffusion, which is prohibitory slow. One key process that needs to be mastered is archiving chaotic mixing of fluids at micro-scale.We propose to investigate the possibilities of achieving global mixing flows in micro-channels and cavities, using multiple, but a finite number of, magnetic particles actuated by an external magnetic field.

To this end we will set up a 3D numerical model that captures the full hydrodynamic and magnetic interactions in the system. Additionally, experiments will be set up to validate the model and to explore practical solutions to the mixing problem. The aim is to achieve optimal mixing using suitable actuation protocols in terms of number and nature of magnetic particles, and time- and space-dependency of the driving magnetic field.