Periodic Reporting for period 2 - MAMI (Magnetics and Microhydrodynamics - from guided transport to delivery)
Berichtszeitraum: 2020-05-01 bis 2022-06-30
This multidisciplinary network bridges the research fields of fluidics and magnetism. We propose to take advantage of magnetic forces to control local flows and cargo transport inspired by biomimetic systems. Using magnetic sources, as well as high magnetic susceptibility liquids or microstructures, we explore how novel fluidic or cargo transport devices with unique properties can be constructed.
There is a strong need of understanding the importance of magnetic forces and materials for controlling the transport of matter at the micron scale. This length scale is mostly unchartered, being the most challenging for the mastering and understanding of magnetic fluids properties. It is also the most challenging for fluid transport, where friction prohibits reliable microfluidics designs circuitry when external control is needed. It is however the most important for the transport of biomaterials. For this purpose, we proposed to build shared knowledge ranging from the technical issues of fabricating appropriate permanent magnetic sources, tackling fundamentals of behavior of (magnetic) liquids under field, designing new type of microfluidic systems involving magnetic and non-magnetic fluids, understanding and characterizing cargo transport of biological entities with the added magnetic input force.
There is a strong need of understanding the importance of magnetic forces and materials for controlling the transport of matter at the micron scale. This length scale is mostly unchartered, being the most challenging for the mastering and understanding of magnetic fluids properties. It is also the most challenging for fluid transport, where friction prohibits reliable microfluidics designs circuitry when external control is needed. It is however the most important for the transport of biomaterials. For this purpose, we proposed to build shared knowledge ranging from the technical issues of fabricating appropriate permanent magnetic sources, tackling fundamentals of behavior of (magnetic) liquids under field, designing new type of microfluidic systems involving magnetic and non-magnetic fluids, understanding and characterizing cargo transport of biological entities with the added magnetic input force.
Fundamentals of structural insight into the behavior of liquids under magnetic field is best gained using neutron diffraction and diffusion techniques. Therefore, a significant investment in the upgrade of a beamline with permanent magnet and electromagnetic apparatuses capable of imposing sufficient magnetic field on a liquid sample has been done, making possible studies under applied magnetic field from 0 to 0.4 Tesla. Elastic properties of liquids have been a focus of our study in order to get a deeper insight into liquid interface instability based local flow. Recent developments reveal that liquids support shear stress like solids provided the length scale is sufficiently small. To further understand this hidden elastic property, collective effects were revealed via stress and temperature measurements, challenging the consensus about the thermo-mechanical response of fluids and providing new insights for a better understanding of paramagnetic liquids and the long range associated effects. The effect of a magnetic field gradient on multicomponent systems containing paramagnetic species and undergoing diffusion was also studied by means of neutron diffraction. This is relevant for understanding how the mixing processes can be magnetically modified. Furthermore, the first study of a paramagnetic salt solutions undergoing capacitive deionisation with emphasis on the magnetic field gradient was carried out. The transport and electrosorption of paramagnetic ions in porous networks present a new area of study. The findings are of interest for a potential magnetically aided separation of rare earths, which may facilitate the purification and recycling of these critical raw materials. This would be valuable both for economic and ecological reasons.
Experiments studying the effect of a uniform magnetic field were performed on water. Insight into contradicting claims in the literature of measurable effects of static magnetic fields have been carried out.
Aiming for integrating permanent magnets in the environment of fluidic circuits, efforts into optimization of the quality, corrosion resistance studies, and fabrication of prototypes were performed by an industrial beneficiary, in collaboration with an academic beneficiary. Investigation of magnetic powder coating by sol-gel method and production of magnets by compression moulding has been done at a laboratory scale. Optimization of process parameters and magnet production were evaluated by measurements of changes of magnetic properties after exposure to corrosive environment.
Inspired by nature, magnetically actuated cilia technology has become the main focus of investigation to four different teams from the MAMI consortium. The ultimate goal is to solve the technical limitations of microfluidics and to achieve precise control over locally driven matter transport. Progress achieved so far are :
-The successful isolation and membrane removal of cilia from single-cell green alga and its reactivation using ATP. This step is followed by the integration of an energy module (artificial mitochondria) and the attachment of cilia to a patterned substrate.
-The fabrication of magnetic artificial cilia in the range of 50- 100 microns of size, with embedded iron and iron oxide particles. The effect of aspect ratio and iron particles concentration on actuation of cilia was investigated.
Experiments studying the effect of a uniform magnetic field were performed on water. Insight into contradicting claims in the literature of measurable effects of static magnetic fields have been carried out.
Aiming for integrating permanent magnets in the environment of fluidic circuits, efforts into optimization of the quality, corrosion resistance studies, and fabrication of prototypes were performed by an industrial beneficiary, in collaboration with an academic beneficiary. Investigation of magnetic powder coating by sol-gel method and production of magnets by compression moulding has been done at a laboratory scale. Optimization of process parameters and magnet production were evaluated by measurements of changes of magnetic properties after exposure to corrosive environment.
Inspired by nature, magnetically actuated cilia technology has become the main focus of investigation to four different teams from the MAMI consortium. The ultimate goal is to solve the technical limitations of microfluidics and to achieve precise control over locally driven matter transport. Progress achieved so far are :
-The successful isolation and membrane removal of cilia from single-cell green alga and its reactivation using ATP. This step is followed by the integration of an energy module (artificial mitochondria) and the attachment of cilia to a patterned substrate.
-The fabrication of magnetic artificial cilia in the range of 50- 100 microns of size, with embedded iron and iron oxide particles. The effect of aspect ratio and iron particles concentration on actuation of cilia was investigated.
The integration of magnetic sources in a fluidic circuit enclosure, and the stabilization of ferrofluid surrounding the cylindrical flow of the liquid of interest has been successfully achieved. A stabilized water cylinder embedded in a ferrofluid enclosure was imaged in 3D by X-ray tomography at the PSI synchrotron light source facility (CH). The team is now capable of stabilizing and imaging tubes down 6 microns diameter. This finding shows how this approach is relevant for the field of microfluidics, in particular for flowing viscous liquids or delicate biological compounds. A resulting milestone publication involving three beneficiaries of the ITN appeared in Nature. Under dynamic flow conditions, particle velocimetry was performed in a fourth partner laboratory, and showed a nearly ideal plug flow of the inside viscous liquid.
Liquid-in-liquid flow is the archetype of non-stable fluid dynamics conditions. However, the addition of magnetic forces makes it remarkably stable, within a wide range of Reynolds numbers. Furthermore, the absence of solid walls strongly diminishes the friction forces. Reduction factors reaching 99,8 % were measured, while usual reports in the literature do not exceed a few tens of percent. Such impressive improvement opens new perspectives for flowing viscous materials in microfluidic channels under small pressure.
Progress in the study of fluids dynamics of ferrofluids small entities under magnetic field have also been obtained. Numerical algorithms for the simulation of three dimensional dynamics of magnetic fluid free interface did not existed so far. Synthesis and investigation of flexible ferromagnetic filaments gives new possibilities for the field of microrobotics and microfluidics, fields developing nowadays very fast.
Design and set up of an actuation system with permanent magnets and electromagnets, with on-chip microscopy and image analysis was achieved. Studies showed how it was possible to transport droplets surrounded by a ferrofluid through an external magnetic field, and magnetic actuation of cilia has been shown. Cell integration and cell culturing in microfluidic devices under the passage of fluid through circulatory system has been performed in frames of Biological Test Platforms and Integration stream. The team evaluated cell adhesion, cytotoxicity, viability and specific functions.
The combination of fundamental understanding of the fluid dynamic of systems sensitive to magnetic forces, the successful realization of magnetic confinement in microfluidic circuits, and the integration of bio-inspired magnetic components in microfluidics devices make this emerging new field promising and mature enough for the book publication in Springer ‘Topics in Applied Physics Series’
Liquid-in-liquid flow is the archetype of non-stable fluid dynamics conditions. However, the addition of magnetic forces makes it remarkably stable, within a wide range of Reynolds numbers. Furthermore, the absence of solid walls strongly diminishes the friction forces. Reduction factors reaching 99,8 % were measured, while usual reports in the literature do not exceed a few tens of percent. Such impressive improvement opens new perspectives for flowing viscous materials in microfluidic channels under small pressure.
Progress in the study of fluids dynamics of ferrofluids small entities under magnetic field have also been obtained. Numerical algorithms for the simulation of three dimensional dynamics of magnetic fluid free interface did not existed so far. Synthesis and investigation of flexible ferromagnetic filaments gives new possibilities for the field of microrobotics and microfluidics, fields developing nowadays very fast.
Design and set up of an actuation system with permanent magnets and electromagnets, with on-chip microscopy and image analysis was achieved. Studies showed how it was possible to transport droplets surrounded by a ferrofluid through an external magnetic field, and magnetic actuation of cilia has been shown. Cell integration and cell culturing in microfluidic devices under the passage of fluid through circulatory system has been performed in frames of Biological Test Platforms and Integration stream. The team evaluated cell adhesion, cytotoxicity, viability and specific functions.
The combination of fundamental understanding of the fluid dynamic of systems sensitive to magnetic forces, the successful realization of magnetic confinement in microfluidic circuits, and the integration of bio-inspired magnetic components in microfluidics devices make this emerging new field promising and mature enough for the book publication in Springer ‘Topics in Applied Physics Series’