In this paper, an electromagnetic actuator having four discrete positions is discussed. The principle, the modeling, and an experimental device of this actuator are presented in this study. This actuator is composed of a mobile permanent magnet, four fixed permanent magnets, which ensure the holding of the discrete positions, and two perpendicular wires to switch independently in two perpendicular directions. The mobile part has four discrete positions, two in each direction. An electromagnetic actuator modeling has been realized to compute the magnetic and electromagnetic forces exerted on the mobile magnet and its displacement. The experimental device was designed using this model and then manufactured. The stroke of the mobile part is 1 mm times 1 mm. The driving current ranges from 3 to 7 A. A comparison between experimental and modeled results is carried out. Good agreement on the displacement curves and on the rise times is observed for all the range of controlling currents.

Fluidized bed bioreactor with alginate beads may be an alternative to hollow fiber cartridge to host hepatocytes for bioartificial liver purposes. After the bioreactor design and the characterization of fluid mechanics, the present study was aimed at analyzing bi-directional mass transfers of calibrated species between external fluid and empty beads. Static (batch) and dynamic (fluidized bed bioreactor) experimental conditions were analyzed. A simple modelling approach permitted the definition of mass transfer coefficients. The motion of beads within the bioreactor clearly enhanced mass transfer kinetics, but did not alter the amount exchanged. The shear enhanced diffusion coefficient for VitB12 was 20 times higher in the fluidized bed bioreactor than under batch conditions, proving the efficiency of such a device.

This paper presents a monolithic multistable micro-actuator based on antagonistic pre-shaped double beams. The designed micro-actuator is formed by two rows of bistable micro-actuators providing four stable positions. The bistable mechanism for each row is a pair of antagonistic pre-shaped beams. This bistable mechanism has an easier pre-load operation compared to the pre-compressed bistable beams method. Furthermore, it solves the asymmetrical force output problem of parallel pre-shaped bistable double beams. At the same time, the geometrical limit is lower than parallel pre-shaped bistable double beams, which ensures a smaller stroke of the micro-actuator with the same dimensions. The designed micro-actuator is fabricated using laser cutting machine on medium density fiberboard (MDF). The bistability and merits of antagonistic pre-shaped double beams are experimentally validated. Finally, a contactless actuation test is performed using 660 nm wavelength laser heating shape memory alloy (SMA) active elements.