Modelling microfabrication and characterisation of nonspiral planar microcoil based magnetic MEMS For biomedical applications

Abstract

newlineMagnetic micro-electro-mechanical-systems (MEMS) involve a new class of MEMS newlinedevices with great potential for magnetic sensing and actuation. Magnetic MEMS newlinedevices are based on electromagnetic interactions between magnetic materials and newlinemicrocoils and/or permanent magnets. Among the different types of microcoils used in newlinethe magnetic MEMS devices, non-spiral planar microcoil is an emerging planar microcoil newlinewith many unique advantages over the conventional spiral planar microcoils. Planar newlinemicrocoils greatly help the miniaturisation of magnetic devices and systems. The newlinefabrication of sensors based on non-spiral planar microcoils proposed in this work newlinerequires only one mask level and one metal level. The non-spiral planar microcoil newlinepossesses a lower series resistance and hence results in reduced Joule losses. newlineIn this research work, an analytical model for magnetic field distribution, peak newlinemagnetic flux density, sensitivity and resolution is developed for non-spiral planar newlinecircular microcoils and the results are verified using experimental results. Comparison newlinewith a conventional spiral planar microcoil of similar dimensions is performed using newlinefinite element analysis. Non-spiral planar microcoils of various geometries are newlinemicrofabricated and characterised to extract the electrical parameters of the coils. The newlinepresented fabrication process is a simple method making use of a single metal level and newlinecompatible with standard integrated circuit manufacturing process. newlineIn this work, an electrical model of a non-spiral planar microcoil is developed and newlinecompared with the experimental results. The relation between electrical and geometrical newlineparameters of the coil is studied, and optimised coil geometry is presented suitable for newlinebiomedical applications. newlineMagnetic sensors based on non-spiral planar microcoils in three different newlineconfigurations are proposed to detect magnetic microbeads.