Periodic Reporting for period 4 - InterActive (Interacting with Active Particles)
Okres sprawozdawczy: 2023-07-01 do 2024-12-31
Physics has been extremely successful in describing and predicting and understanding properties of all kinds of materials. However, biological and living materials pose challenges due to their complexity and dynamics. Therein, one frontier of research is so called active matter, which refers to self-propulsive objects that can interact with each other and with their environment leading to complex and important behaviors. Examples of active particles include biological ones, such as flocking birds, swarming microbes and schooling fish. In addition, synthetic objects that mimic the behavior of these biological active particles can be nowadays prepared using various physical and chemical techniques. While many of these systems are easy to observe – birds and the flocks with binoculars or with a naked eye, bacteria with a simple optical microscope, and so on, it is still very difficult to interact with these, often small and fast, active objects to study them beyond simple observation. Our understanding of the behavior of the active particles, both at single particle and collective levels, is still very limited, partly because of lack of ideal experimental tools to interact with them.
The understanding of material behavior arising from scientific research is historically known to be extremely useful for the humankind. Concrete examples of this can be seen everywhere around us: semiconductors in computers and mobile devices, advanced alloys in transportation systems, increasingly biodegradable plastics in consumer products and packaging, liquid crystals in TV panels, and so on. Active particles and materials studied in this project are among the new frontiers of materials research. The results of this project will give scientists new tools to study these complex systems, leading to improved understanding of the behavior of biologically relevant micro-organisms as well as synthetic active particles that are envisioned to be functional components in next-generation technologies.
The overall objective of this project was to develop new tools for interacting with active particles to study their behavior beyond what is possible currently. The new tools are based on utilization of magnetic fields and forces. As a conclusion, we have demonstrated in this action that such tools are indeed possible and we have experimentally applied them successfully to investigations of both living biological and synthetic active matter systems.
The understanding of material behavior arising from scientific research is historically known to be extremely useful for the humankind. Concrete examples of this can be seen everywhere around us: semiconductors in computers and mobile devices, advanced alloys in transportation systems, increasingly biodegradable plastics in consumer products and packaging, liquid crystals in TV panels, and so on. Active particles and materials studied in this project are among the new frontiers of materials research. The results of this project will give scientists new tools to study these complex systems, leading to improved understanding of the behavior of biologically relevant micro-organisms as well as synthetic active particles that are envisioned to be functional components in next-generation technologies.
The overall objective of this project was to develop new tools for interacting with active particles to study their behavior beyond what is possible currently. The new tools are based on utilization of magnetic fields and forces. As a conclusion, we have demonstrated in this action that such tools are indeed possible and we have experimentally applied them successfully to investigations of both living biological and synthetic active matter systems.
In the first half of this highly interdisciplinary and experimental project, we developed several new magnetic techniques for interacting with active particles by using magnetic fields. We also developed deeper understanding of the model active particles used in this project, which include C. reinhardtii microalgae, E. coli bacteria, and electrohydrodynamically driven Quincke rollers, which are among the important model systems in the field of active matter. We carried out synthesis of various novel magnetic particles and magnetic fluids (ferrofluids), the best of which were applied to controlling the aforementioned active particles.
Overall, this project led to new magnetic materials, magnetic fluids and magnetic methods for interacting with active matter. Results have been published in several scientific journal articles and presented at international conferences, as well as highlighted on different news websites ( https://www.aalto.fi/en/news/getting-bacteria-into-line , https://phys.org/news/2021-12-tuning-magnetic-fluid-electric-field.html , https://phys.org/news/2023-07-magnetic-quincke-rollers-torques-magnetism.html ).
Overall, this project led to new magnetic materials, magnetic fluids and magnetic methods for interacting with active matter. Results have been published in several scientific journal articles and presented at international conferences, as well as highlighted on different news websites ( https://www.aalto.fi/en/news/getting-bacteria-into-line , https://phys.org/news/2021-12-tuning-magnetic-fluid-electric-field.html , https://phys.org/news/2023-07-magnetic-quincke-rollers-torques-magnetism.html ).
In this project we progressed beyond the state of the art in many ways, including by developing novel magnetic fluids. We further developed first magnetic Quincke rollers and demonstrated their control with magnetic fields and potential energy landscapes (https://www.science.org/doi/10.1126/sciadv.adh2522(odnośnik otworzy się w nowym oknie)). We further demonstrated that the magnetic methods are useful for controlling living systems, including regular non-magnetic bacteria (Bacillus subtilis) where we could at low bacterial concentrations control individual cells and at high concentrations their collective behaviors like active turbulence (https://www.nature.com/articles/s42005-024-01707-5(odnośnik otworzy się w nowym oknie)). We have also discovered various new phenomena in electrohydrodynamically driven liquids, including active electrohydrodynamically propelled liquid droplets.