M. Feldmann

Microoptical distance sensor with integrated microoptics applied to an optical microphone

The developed fiber optical microphone (FOM) using intensity modulation of light is based on triangulation. Emitted light from an LED is directed through an optical fiber onto the membrane. The reflected light is coupled into the receiving fiber. Vibration of the membrane results in a toggling of the light spot on the receiving fiber. Consequently a change in intensity can be detected at the photo diode. The sensor characteristics are determined mainly by the coupling between the transmitting and receiving fiber. The crucial parameter is the steepness of the dependency of the transmitted intensity on the distance to the reflecting surface. We optimized the geometrical design parameters and developed an integrated micro-macro-interface with high precision self-adjustment for optical components - the micro optical distance sensor. Introducing new concepts by using integrated microoptics leads to a significant improvement of the sensors characteristics, such as higher sensitivity and dynamic range

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.

New generation of integrated position sensor systems for parallel robotic applications

The performance of micro and large-sized parallel robots is improved by implementing machine-oriented control tasks. Internal sensors integrated in structural robot components like rods and joints transmit relevant data for this purpose. Considering this background, linear and angular sensors have been developed at the Institute for Microtechnology during the last years. In this paper, the new generation of MEMS position sensors for such applications is introduced. The presented sensors are characterized by an easy integration in parallel kinematics and contactless working principles with high resolution. Micro manufacturing and characteristics are discussed and the suitability of the sensors for parallel robotics is pointed out.

Electromagnetic Parallel Microrobot for Micro- and Nano-Handling

In this paper we report on a novel parallel micro robot driven by Lorentz force actuators. The micro robot consists of three linear micro actuators positioned in plane forming a planar parallel kinematic structure. Each actuator is connected by polymer flexural hinges to a triangular frame in the center of the structure serving as the end effector. Advantages of such micro actuators are the facts that their displacement increases with increasing current and that they exhibit good linear characteristics according to the Lorentz force law. Therefore they allow high precision displacements. Due to the freely suspended structure, friction can be disregarded, and first movements occur already at a current of 10 µA, which results in very low thermal effects. For application to micro-and nano-handling the precise measurement of the displacement of each actuator is very important. Therefore, special capacitive micro sensors are integrated into the system, which consist of comb-like structures constituting differential capacitors. Currently, these micro sensors allow controlling the end effector in a closed loop control with high precision of 1.3 nm within a workspace of 400 µm x 400 µm.