Development of circumference oscillation mechanism with adjustable amplitude
According to the situation of the currently developed circumference oscillation mechanism without adjustable amplitude generally. The circular oscillation mechanism with adjustable amplitude is designed. It mainly comprises an eccentric motion mechanism and adaptive dynamic balance mechanism. The dynamic simulation and analysis is carried out on eccentric motion mechanism. The experimental results show it can achieve 0-Φ50mm adjustable amplitude and 20-350RPM adjustable oscillation frequency in the meantime, and the latter can be realized by changing eccentricity adjusting pin manually. The unbalance quality of the table can be compensated by adaptive dynamic balance mechanism in order to increase the die life. Its amplitude can be changed simply, conveniently and fast, and has the characteristics of simple and compact mechanism, rigid connection, strong bearing capacity and maintenance easily. It will be widely used in the field of biological engineering.
Prediction and simulation on the shear stress and mass transfer in perfused bioreactors I: Circular bioreactors
Bioreactors have been widely used in tissue engineering because of their controllability in environments and operating conditions. But bioreactor design is very complex and still at an early stage of development. Computational fluid dynamics (CFD) is commonly used for the design and manufacture of devices with fluid flow as a powerful computer ldquoexperimentsrdquo modelling and simulation tool. In our work, by the CFD simulations of different circular bioreactors with various parameters, we obtained the concentration status of glucose and lactate in different time and shear stress. It was shown that the inlet or outlet position, and the feed flow rate have quadric relationship with the shear stress. In order to provide the cells with comfortable culture environment, bioreactors should have a lower outlet than inlet, the Hc/Ho should be between 0.2 and 0.4 and the fluid exchange ratio Rfe should be between 0.68 and 6.84 hours.
Bioreactor-free tissue engineering: directed tissue assembly by centrifugal casting
Casting is a process by which a material is introduced into a mold while it is liquid, allowed to solidify in a predefined shape inside the mold, and then removed to give a fabricated object, part or casing. Centrifugal casting could be defined as a process of molding using centrifugal forces. Although the centrifugal casting technology has a long history in metal manufacturing and in the plastics industry, only recently has this technology attracted the attention of tissue engineers. Initially, centrifugation was used to optimize cell seeding on a solid scaffold. More recently, centrifugal casting has been used to create tubular scaffolds and both tubular and flat multilayered, living tissue constructs. These newer applications were enabled by a new class of biocompatible in situ crosslinkable hydrogels that mimic the extracellular matrix. Herein the authors summarize the state of the art of centrifugal casting technology in tissue engineering, they outline associated technological challenges, and they discuss the potential future for clinical applications.