MOEMS transducer with a non-linear transfer characteristic for static displacement measurement applications on the example of an inclination sensor

• Published in: Sensors and actuators. A. Physical. 2017-08, Vol.263, p.727-732
• Main Authors: Steiner, H., Hortschitz, W., Kainz, A., Stifter, M., Jachimowicz, A., Schalko, J., Keplinger, F., Kohl, F.
• Format: Article
• Language: English
• Subjects: Amplifiers; Apertures; Arrays; Displacement measurement; Earthquake construction; Harmonics; Heat transfer; Inclination; Measurement; MOEMS; Non-linear transfer characteristic; Resolution; Sensors; Static displacement; Transducers
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2017.05.035

•A MOEMS transducer with a non-linear transfer characteristic is presented.•The MOEMS is based on the modulation of a light flux that passes through a pair of micro apertures.•The non-linear characteristic is exploited for the quantification of static displacements.•The presented approach can be used to increase the resolutions compared to simple DC measurements. This contribution describes an micro-opto-electro-mechanical system transducer with a well defined inherent non-linear transfer behavior and its impact on the quantification of static and dynamic displacements in a vibrating measurement mode. The transducer’s output signal is proportional to a light-flux that is modulated by two overlapping aperture arrays. One of these arrays is deposited on a fixed glass cover while the other one is etched into a moveable seismic mass of a silicon micro-electro-mechanical chip. The non-linear transfer characteristic is achieved by pairing triangularly shaped apertures with rectangular ones. The seismic mass is actuated by a mechanical shaker unit and the resulting first and second harmonics of the output signal are recorded with lock-in amplifiers. These harmonics contain information about both the static displacement and the vibration amplitude of the seismic mass. The presented method was tested with a proof-of-concept device and first measurement results exhibit a static displacement resolution of 3.67nm which is a slight improvement compared to DC measurement approaches exhibiting a resolution of 5.39nm. Furthermore, a inclination sensor was built employing this vibrating measurement approach showing that the resolution was improved at least by an factor of three.