Making optical MEMS sensors more compact using organic light sources and detectors

Vibration and displacement sensors need to be compact for many applications in automation or consumer electronics, and microelectromechanical structures are a convenient way to implement such sensors. For these MEMS devices, optical readout methods have proven to be superior to capacitive or piezoresistive strategies in terms of sensitivity as well as noise and interference immunity, however the integration of light sources and detectors is not easily possible. This paper presents an approach to use organic optoelectronic devices for the readout. OLED and OPD (organic photo detector) are structured on the glass substrate and cover encapsulating the MEMS devices, allowing for a tightly integrated sensor based on vertical light flux modulation by a horizontally moving proof mass. The paper describes the principle sensor structure as well as the fabrication of suitable organic devices. First test results show that the approach is feasible.