Fabrication, characterization, and modelling of a novel via-less single metal level magnetic microcoil sensor for biosensing applications

Abstract

The emerging field of micro dimensioned biomedical sensors involves tremendous research to detect biomolecules and pathogens with an improved sensitivity and a low limit of detection. The use of magnetic labels in biosensors has increased so much over the past years due to unique advantages of magnetic sensing techniques. Planar microcoil based magnetic biosensors help to reduce the system size and improve the sensitivity. This paper proposes non-spiral planar microcoil based magnetic sensors which are advantageous over conventional spiral coil based sensors regarding fabrication easiness and heating losses. The method of microfabrication of the coil sensor described in this paper makes use of a single mask process which is the simplest among all existing processes. Non-spiral planar microcoil sensors based on induction-balance and differential sensing principles are studied in this work. Also, an analytical model is developed to design the dimensions of the sensing coil. Comprehensive finite element analysis of the sensors is performed, and the results are compared with the experimental outcomes. A comparative study of the proposed sensors with the existing planar coil magnetic sensors is also presented to show the advantages of the proposed coil sensors over the existing ones.