Thomas Nussbaumer

Viral nanotechnology enables new possibilities for gene therapies and vaccines. However, the manufacturing of viral vectors lacks a production capable method for purification of full capsids. Empty or partially empty capsids need to be removed to avoid immunotoxicity. The state of the art production ultracentrifuges (PUCFs) are limited, especially in rotational speed to approximately 40 krpm by rotary seals, by complexity and virus containment. This prevents PUCFs from widespread use in industry for viral vector production. This article proposes a novel PUCF type with rotational speed potential towards 100 krpm with a hermetically enclosed process chamber without any rotary seals, i.e. a sealless production ultracentrifuge (SL-PUCF) omitting contamination risk. The openable vertical axis self-bearing motors, the novel sealless flow path design and the needed ultra high-speed potential towards 100 krpm pose new technical problems, for which this article proposes and experimentally validates solutions. A SL-PUCF prototype with its vertical axis magnetically self-bearing openable motors (O-SBMs) and openable burst armor (O-BA) are realized validated and operated as a system. The general working principle of the SL-PUCF system is experimentally validated by whey protein sedimentation. Furthermore, new future smart capability potential of the proposed new SL-PUCF technology suspended and driven by O-SBMs is unveiled as an outlook and examples shown in case studies.

For magnetic bearing manufacturers, the installation situations in systems in the field are often unknown and not accessible. Hence, the final system vibration spectrum with respect to excitations by operating the system and therefore mechanical resonances are unknown as well. But to avoid failure, they need to be known before the speed is initially ramped-up in a magnetic bearing suspended system. Therefore, there is a need for an experimental method to predict and prevent already at rotor standstill risks due to plant mechanical resonances. This article shows theoretically and experimentally that conventional magnetic bearing rotor displacement measurement is insensitive on mechanical system resonances. As a solution, two new acoustic response methods are proposed, which can completely detect the system mechanical resonances that will occur during operation already in the standstill levitating state. Furthermore, it is shown with application case studies that these methods can be used for condition monitoring to detect deteriorating changes in the system before rotor speed ramp-up.

A novel magnetically double self-bearing drive system for ultracentrifugation in pharmaceutical and chemical industry is presented, built as a prototype and operated. The prototype successfully reached its operating speed of $100^{\prime }000\,\text{rpm}$ . It features an opening stator functionality allowing for fast removal of the ultracentrifuge rotor while enabling future centrifugal acceleration levels of $200^{\prime }000\,\mathrm{g}$ . The openable stators require a stator encapsulation, provoking unavoidable stator yoke air-gaps. Parasitic induced phase-currents were identified, a current-control strategy proposed to diminish them and successfully implemented and operated on the prototype.

This study conducted a comparative evaluation of two bearingless cross-flow fan designs for applications in deep ultraviolet lithography excimer lasers, where maximizing the speed and power of the fan has a direct influence on the throughput and scanning speed of these devices. Using bearingless motor technology enables a combined generation of bearing force and drive torque and leads to a compact, hermetically sealed, and conveniently maintainable drive system. With identical bearingless motors on both rotor sides, it is possible to drive the cross-flow fan symmetrically to high rotational speeds at low torsional loads. The rotor prototypes were optimised, analysed, and pushed to high-speed operation and evaluated with respect to their rotor dynamic and fluid dynamic performance using finite element methods and experimental measurements. For both prototypes, successful numerical studies were performed, where a modal analysis enabled theoretical predictions of expected resonance frequencies, and a CFD analysis visualised local flow effects and provided cross-flow fan design comparisons. A stable operation of up to 12,000 rpm and 5500 rpm was accomplished for the two elaborated designs.

In this paper, the design and operating principle of a slotless bearingless slice motor for high rotational speeds is presented. The performance of the proposed concept is evaluated using an experimental prototype. Measurement results demonstrate a stable dynamic behavior during acceleration and an achievable rotational speed of 150 000 rpm, which is, to the knowledge of the authors, the highest rotational speed attained by a bearingless slice motor to date. The system performance is outlined at its maximum speed and power loss measurements are carried out over the entire speed range.

Stirred tank bioreactors are still the predominant cultivation systems in large scale biopharmaceutical production. Today, several manufacturers provide both reusable and single-use systems, whereas the broad variety of designs and properties lead to deviations in biological performance. Although the methods for bioreactor characterization are well established, varying experimental conditions and procedures can result in significantly different outcomes. In order to guarantee a reliable comparison and evaluation of different single-use and reusable bioreactor types, standardized methods for their characterization are needed. Equally important is the biological capability of bioreactors, which must be accessed by standardized cultivation procedures of industrially relevant organisms (bacteria, yeasts as well as mammalian and animal cell cultures). In addition, the implementation of well-defined uniform procedures for biological and engineering characterization during the development phase can support a fast assessment of the suitability of a bioreactor system. Based on stirred bioreactors, we describe the aspects of the engineering characterization in order to discuss further the biological characterization as a valuable complement. Finally, a case study is presented.