Optical dew point sensor with integrated primary electronics based on silicon-ceramic composite technology

Inhalt:
The dew point is the temperature to which air must be cooled down to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced, and airborne water vapor will condense to form liquid water known as dew. The relationship between dew point and relative humidity is the basis for dew point hygrometers, which are commonly used in industry for high-precision humidity measurements and are essential for industrial and metrology applications. However, these devices have several limitations such as large size and slow response. In this paper, we present a compact optical dew point sensor that features a small footprint of a few centimeters, a low response time of 12 s, and integrated primary electronics. The innovative approach of combining low temperature cofired ceramic (LTCC) with silicon technology combines two fundamentally different fabrication technologies and substrate materials, each with its own characteristic advantages and requirements. In this work, for the first time to our knowledge a sensor manufactured with an industrially suitable process flow on wafer-level for silicon ceramic composite material technology is presented.