Integration of optically pumped magnetometers and microfluidics for the determination of the magnetic moments of single micro-particles (Micromagnetic Moments)

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Magnetotactic bacteria (MTB) produce magnetic nano-crystals, arranged in chains and called magnetosomes. Their perfection outperforms abiotically produced nanoparticles, making them interesting for several technical applications. For the MTB themselves the magnetosomes serve for the orientation within the Earth magnetic field. Size, arrangement, und magnetization of the magnetosomes depend on various influencing factors of their environment. The investigation of these interrelations is of growing interest, because the microbes play an important role within the global biogeochemical cycles. For the characterization of MTB as well as biogenically produced magnetosomes the knowledge of their individual magnetic moments would be of great benefit. To gain this individual property within an ensemble of many MTB, no method exists up to now. Hence, in this project a possibility shall be created, where a larger quantity of magnetosomes or MTB (more generally called micro-particles) can be characterized individually with respect to their magnetization with high throughput. For that purpose optically pumped magnetometers (OPM) and micro-fluidic elements are to be integrated in a common chip. Due to the small distance between the bypassing magnetic micro-particles and the alkali vapor cells achievable with this integration, for the first time the determination of magnetic moments of the order of m = 1x10exp(-15) Am^2 will be possible (despite the miniaturized vapor cells, which are needed to resolve individual micro-particles). In order to gain the corresponding magnetic field resolution, several alkali vapor cells will be integrated together with the microfluidic canal, what serves for the elimination of noise sources and improvement of the signal quality. Furthermore, the physical working mode of the OPM has to be developed and fit to the technical situation in the integrated arrangement.