With stacked silicon photodiodes and refined optical thin film filters, spectrally sensitive detectors can be developed that can replace conventional, expensive spectrometers needed for special applications. A further feature of such spectral sensors is the elimination of measurement errors caused by undesirable polarization of the radiating source when fiber-optical sensors are used.
The MEMS technologies available and refined at CiS Research Institute were the basis for the development of a new generation of spectral sensors consisting of two detector chips stacked on top of another, each covering a specific spectral range. The upper diode is only 50 µm thin.
The compact assembly of the detector chips including filters, beam shaping elements, fiber coupler as well as electronics and housing allows a minimum sensor size just slightly larger than an ordinary APC connector. The opto-electronic converter is also available as an SMD component. The contacts are located on the back of the chip and enable the undisturbed incidence of light on the detector.
The new solution concept targets applications with a small wavelength range to be monitored. Narrow-band filters provide picometer accuracy when detecting the wavelength shifts. In addition, vibrations up to 1 MHz are measurable time-resolved with low noise.
Based on the developed micro-technologies and the proven system design a variety of customized sensor solutions can be implemented, for example for the monitoring of bridges, wind turbines and aircraft wing units or for the measurement of the surface plasmon resonance in biotechnology or pharmacy.
The research and development work in the project 3D-Spek-Sens was funded by the German Federal Ministry of Economics and Energy (Funding Code: MF130140).
Contact: CiS Forschungsinstitut für Mikrosensorik GmbH, Uta Neuhaus,
uneuhaus@cismst.de
