Claudio Maggi is currently a tenured researcher at the Institute of Nanotechnology (NANOTEC), of the National Research Council (CNR), hosted by the University “Sapienza” of Rome. His research interests range from soft matter and biophysics to statistical mechanics. In the last years he has been studying experimentally the motility of different microorganisms such as swimming E. Coli bacteria and sperm cells. His research has also focused on the design and actuation of synthetic active particles (e.g. Janus particles) and micro-motors. On the theoretical side he has studied various schematic models of active particles to highlight the origins of non-equilibrium phenomena appearing in these systems.
Wednesday April 19th
Sperm cells in micro-traps: motility sorting and swimming precision
Sperm swimming is crucial to fertilise the egg in nature and in assisted reproductive technologies. In this talk I will show how we have implemented a passive technique for the amplification of motile bull sperm concentration. This is realised by building micro-chambers capable of trapping swimming sperms yielding a significant enhancement of motile cells density in the traps. Fabricating chambers with different shape and size highlights the ingredients that are key to optimal trap design. In the second part of the talk I will show we have used an array of micro-cages to trap the sperms’ cell bodies and accurately track the spatial modes of the sperms’ flagella during their beating cycle. By studying accurately the fluctuations of the dynamics of the flagellum we find that the maximum precision of this motion is close to the estimated precision of one single dynein molecular motor actuating the flagellar axoneme. I will discuss how the maximum precision of individual molecular motors is related to their energy dissipation by the thermodynamic uncertainty relation and how the precision level of the whole flagellum can be explained by a schematic model with strong motor-motor coupling.