A. Waldschik

Implementation of Synchronous Micromotor in Developing Integrated Microfluidic Systems

This paper introduces the synchronous micromotor concept and presents new investigations on its application as an integrated driving mechanism in microfluidic systems. A spiral channel viscous micropump and a microstirrer are considered and tested as examples to verify the concept. The fabrication technology of such integrated systems is based on UV depth lithography, electroplating and soft lithography. The synchronous micromotor consists of a stator including double layer coils, and a rotor disk containing alternate permanent magnets. The coils are distributed evenly around the stator and arranged in three phases. The phases are excited by sinusoidal currents with a corresponding phase shift resulting in a rotating magnetic field. Regarding the spiral channel viscous micropump, a spiral disk was fixed onto the rotor disk and run at different rotational speeds. Tests showed very promising results, with a flow rate up to 1023 µL·min−1 at a motor rotational speed of 4500 rpm. Furthermore, for the application of a microstirred-tank bioreactor, the rotor disk design was modified to work as a stirrer. The performance of the developed microbioreactor was tested over a time period of approximately 10 h under constant stirring. Tests demonstrated the successful cultivation of S. cerevisiae through the integration of the microstirrer in a microbioreactor system. These systems prove that synchronous micromotors are well suited to serve as integrated driving mechanisms of active microfluidic components.

Development and Fabrication of Electromagnetic Microactuators

In recent years several photoresists were introduced, tested, and optimized for the fabrication of components for electromagnetic microactuators. They serve as insulation layers as well as mold for electroplating of different materials like copper for conductors and nickel-iron alloys for soft magnetic functional structures. Several electromagnetic microactuators were developed and fabricated using these techniques. Over the past few years the actuators have become increasingly complex through the integration of additional components. The range of electromagnetic actuators could be completed by special polymer magnets which enable creation of any shape of hard magnetic structure. Thus, all types of electromagnetic actuators based on reluctance as well as the electro-dynamic principle can be realized.