Lars Beglinger

Last Name

Beglinger

First Name

Lars

ORCID

0000-0002-0444-1714

Show all metadata

Search Results

Publications 1 - 5 of 5

Modeling, evaluation, and optimization of a self-bearing spinfilter for bioseparations
Beglinger, Lars; Steinert, Daniel; Nussbaumer, Thomas; et al. (2025)
Separation and Purification Technology
Rotating filters promise many advantages for long-term separation processes of complex media such as cell cultures, but have never been commercialized on a large scale due to practical challenges and limited scalability. A bearingless spinfilter circumvents many of the drawbacks, yet additional considerations must be taken into account. Thus, an existing particle-force based model for cross-flow filtration, dependent on the membrane shear rate and the transmembrane pressure, is adapted to the spinfilter and predicts the behavior of retained particles at the membrane. Computational fluid dynamics simulations allow to calculate the shear rate at the membrane for the model. Additionally, with the simulated distribution of the shear rate and the energy dissipation rate within the spinfilter, a prediction of the hydrodynamic stress on cell cultures can be made. The model is verified with a spinfilter prototype on a yeast cell culture and is in good agreement with experimental results. Additional separation experiments with bovine blood serve to indicate the extent of cell damage induced by hydrodynamic stress within the spinfilter. The results demonstrate that operating the spinfilter at the optimum operation point leads to a faster separation process at a lower level of cell damage per volume of filtrate in comparison to a passive tangential flow filtration in hollow fibers.
Experimental evaluation of bearingless spinfilter topologies
Beglinger, Lars; Zürcher, David; Steinert, Daniel; et al. (2024)
Separation and Purification Technology
Rotating filter membranes can increase the long term filtrate flux by efficiently and continuously removing the retained particles on a microfiltration membrane. However, the practical implementation of rotating machinery in high purity applications such as biotechnological manufacturing of proteins raises concerns about the contamination of the process fluids due to submerged bearings and imperfect sealings to the outside environment. Bearingless and hermetically sealed spinfilters provide a solution to these drawbacks, but create challenges due to the contactless operation, and consequentially, the open internal gap between the feed and the filtrate. To address this, five bearingless spinfilter topologies to reduce the remixing across the open gap are proposed, experimentally evaluated, and discussed. Three spinfilter topologies reach a filtrate purity of 100 %, while the best performing concept reaches specific filtrate fluxes of over 2300 L h−1 m−2.
Reaction Force-Based Position Sensing for Magnetic Levitation Platform with Exceptionally Large Hovering Distance
Bonetti, Reto; Beglinger, Lars; Miric, Spasoje; et al. (2024)
Actuators
This work introduces a novel sensing concept based on reaction forces for determining the position of the levitating magnet (mover) for magnetic levitation platforms (MLPs). Besides being effective in conventional magnetic bearings, the applied approach enables operation in systems where the mover is completely isolated from the actuating electromagnets (EMs) of the stator (e.g., located inside a sealed process chamber) while levitating at an extreme levitation height. To achieve active position control of the levitating mover by properly controlling the stator’s EM currents, it is necessary to employ a dynamic model of the complete MLP, including the reaction force sensor, and implement an observer that extracts the position from the force-dependent signals, given that the position is not directly tied to the measured forces. Furthermore, two possible controller implementations are discussed in detail: a basic PID controller and a more sophisticated state-space controller that can be chosen depending on the characteristics of the MLP and the accuracy of the employed sensing method. To show the effectiveness of the proposed position-sensing and control concept, a hardware demonstrator employing a 207 mm outer-diameter (characteristic dimension, CD) stator with permanent magnets, a set of electromagnets, and a commercial multi-axis force sensor is built, where a 0.36 kg mover is stably levitated at an extreme air gap of 104 mm.
The Bearingless Spinfilter
Beglinger, Lars (2025)
Filtration is one of the oldest process engineering techniques known to humanity. While the technology was used exclusively for the treatment of drinking water in ancient times, the separation process is now widely applied in modern industries such as biotechnology. When the particle concentrations in the suspension to be filtered are high, the filter membrane is quickly covered by the retained particles, which leads to a decrease in filtration performance over time. Hydrodynamic methods can be used to remove the retained particles from the membrane surface. For this purpose, different filter modules and geometries are researched. One type of filter that can generate high shear rates locally on the membrane in the filter module is a rotating filter membrane in an annular gap. This work is the first to deal with the design, commissioning, testing, and optimisation of a bearingless spinfilter in which the rotating filter membrane is held in magnetic levitation in the annular gap. Compared to conventional spinfilters, the bearingless drive system allows the rotor to be actuated without contact in a hermetically sealed housing, eliminating the need for rotating seals to the environment that are a source of potential leakage and contamination of the fluid. Bearingless spinfilters do, however, present some challenges in the design and implementation. In particular, a moving membrane creates an open gap between the suspension and the permeate, leading to potential back-mixing after the separation process. Different concepts, called topologies in this thesis, are analysed and tested to reduce the leakage flow to achieve the highest possible permeate purity. The bearingless drive system must adapted for the spinfilter. In doing so, different motor structures are considered and the deflection of the rotor due to the passive axial stability when axial forces act on the rotor is compensated. With the help of measurements, analytical models and CFD simulations, the optimal operating point and the cell damage of the separation process are determined. Measurements show a tripling of the normalised membrane flux compared to filter modules with passive overflow, while using the same filter membrane. Additionally, less cell damage due to hydrodynamic stress on live cells is in the spinfilter compared to a state-of-the-art filter module. Finally, the developed bearingless spinfilter will be placed in the context of industrial applications. In particular, the limited scalability is discussed and a vibrating filter membrane is presented as a comparable alternative to rotating filters.
Concept and Design of a Bearingless Spinfilter
Beglinger, Lars; Steinert, Daniel; Nussbaumer, Thomas; et al. (2023)
IEEE/ASME Transactions on Mechatronics
In many separation processes, filtration performance degrades over time due to retained particles blocking the flow through the filter membrane. A novel bearingless spinfilter extends the long-term performance by self-cleaning effects. The filter rotor is magnetically levitated and actuated by two self-bearing motors inside a hermetically sealed housing, which eliminates the need for bearings and rotary sealings, that both lead to process fluid contamination. Both bearingless motors have integrated electronics and independently control the levitation of the spinfilter rotor. A first prototype is designed and the concept is validated by the separation of a yeast cell culture. Special focus is placed on the internal rotary seal between the feed and filtrate regions, that is inevitably created when the filter membrane is in motion. Any leakage flow through the seal leads to filtrate impurities, which is minimized in this article with an embedded impeller as a pressure compensation method. A constant filtrate flux of 1750 Lh⁻¹m⁻² and a filtrate purity of 75% was achieved in a first series of tests.

Publications 1 - 5 of 5

Lars Beglinger

Last Name

First Name

ORCID

Organisational unit

Filters

Search Results