Mikrosystemtechnische Sensoren in relativ bewegten Systemen für die industrielle Anwendung

Abstract

The present thesis addresses two major fields. First, the dynamic measurement of displacement with a resolution of micrometers is considered. Second, the development of a new class of capacitive micromachined ultrasonic transducers (cMUT) is performed. Within the first scope, an exemplary field of application, i.e. the gripper of a robotic handling system, has been chosen. The commonly employed sensor principles for these purposes are reviewed. In addition, a number of three sensor principles has been selected for an experimental investigation. These distance sensors work within a measuring range of 200 µm up to 3 mm and a resolution of a few micrometers was targeted. Their usability has been specified in terms of repeating accuracy ("Wiederholpräzision").Going on from this preselection of sensor principles, the ultrasonic transducer has been chosen for further development. The state-of-the-art of ultrasonic transducers for air-borne ultrasound is outlined. The given drawbacks of the prevailing thickness mode resonators motivate the development of different transducer principles. One alternative is given by membrane resonators. Here, the ultrasound is generated by the electrostatic stimulation of the membrane, whereas the detection of ultrasound is performed by the measurement of changes in the capacitance of the transducer. Within this thesis it is shown that the microsystem technology offers advantageous possibilities to manufacture ultrasonic transducers with a number of new distinctive features. In particular, the technologies of surface micromachining were employed to develop a novel transducer set-up Since the fabrication of cMUT by means of microsystem technology emerged in 1994, two varying set-ups have been realized that differ from the present one. In contrast to those, the present set-up of a cMUT is particularly suitable for low voltage applications.