Microsensor detection of the direction of light incidence
The CiS Research Institute has developed a tiny microchip for determining the direction of light incidence, thus making a contribution to climate protection. The small size and simple integrability as well as the MEMS manufacturing technology suitable for mass production characterize this component. The monolithic sensor is based on four integrated photodiodes in a 3D-structured silicon substrate.
Sensors for detecting the angle of incidence of light are known, for example, from tracking systems of photovoltaic systems. They are used to increase energy efficiency. Typically, they consist of multiple, discrete electronic and optical components whose assembly is complex. Due to manufacturing constraints, these hybrid setups are less compact and the specimen dispersion of the sensor characteristics is larger.
The new RISEQ sensor technology of the CiS Research Institute enables the development and production of monolithically integrated, direction-sensitive sensors. The basic concept is based on the integration of four photodiodes in the walls of a cavity in silicon. Depending on the design, the size of the sensor chip can be less than 1 mm³. The monolithic design of the sensor proves to be insensitive to vibrations. The RISEQ sensor technology enables low manufacturing costs and minimal component dispersion, as well as high reproducibility accuracy of angle determination.
With these features, RISEQ sensors are attractive for all applications that require direction-dependent determination of light incidence. A first application scenario is being tested in an ongoing cooperation project. The ultra-flat sensor module with the 4-quadrant photodiode is integrated in a window pane for this purpose and precisely detects the incident direction of daylight for controlling facade-integrated shading systems. Other applications are possible for beam steering in laser technology, the control of smart displays or automotive safety.
The research and development work described was funded by the German Federal Ministry of Economics and Climate Protection (BMWK) in the research project "Direction-sensitive quadrant detector (RISEQ), FKZ: MF130154, and in the research project "LightControl" FKZ: (ZF4001704GM9, ZIM).