Planar inductors for detection of magnetic nanoparticles in a paper-based water quality monitoring system

Details

Supervisors

Raskin, Jean-Pierre

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électricien, à finalité spécialisée

Abstract

Water quality is a central concern for human health and environmental preservation, particularly in remote areas where access to drinking water is difficult. Faced with this need, the development of a point-of-care biosensors is emerging as a promising solution to carry out analyses in the field, without the need for specific technical knowledge or equipment. One of the strategies being considered for the quantification of bacterial concentration in water is based on magnetic nanoparticles that bind to bacteria and are then detected with planar inductors, which have the advantage of being economical and easy to produce. This research focuses on the in-depth analysis of these planar inductors and their role in the detection of magnetic nanoparticles. The goal is to use a pair of exciting and sensing inductors in a differential fashion to refine the detection sensitivity. In this study, we develop theoretical models to derive the electrical parameters from the geometric specifications of the inductors. Our results highlight the performance of the exciting and sensing inductor pair, underlined by a variation of 4 to 5% of the initial voltage in response to the presence of ferromagnetic materials with a surface area of 1 cm², as well as a variation of 0.001 to 0.002% caused by the presence of magnetic nanoparticles. Possible improvements, particularly in terms of magnetic coupling, have been proposed, allowing a maximum k-factor of 0.46 for the design of a simple pair of internal/external inductors. Other designs, such as interleaved inductors, have been suggested to achieve magnetic coupling coefficients greater than 0.6. In addition, the study of differential systems integrating these inductors reveals a clear potential to make the system almost 10 times more sensitive. This work thus paves the way for functional and efficient magnetic nanoparticle detectors for water quality monitoring.