1 Standard Humidity Sensors

Figure 1-1 shows two standard humidity sensor components whose sensing elements are exposed on the top (HDC2080) and on the bottom (HDC2010). These sensors have integrated ADCs and are designed to accurately and reliably measure and output the percentage relative humidity (%RH) and temperature data on an I2C-bus.

The capacitive sensing element is composed of a moisture-sensitive polymer as a dielectric and comb metal structure as the capacitance’s electrodes. A change in humidity correlates with the capacitance change with the entire sensing element structure is integrated on a top layer of a standard CMOS technology process. The capacitance value is converted to analog output voltage that is fed to the ADC and the proprietary linearization engine, and as a result, the percent RH value is computed and output is consistent, predictable, and accurate.

The sensor dielectric’s polymer is generally dust resistant and excellent for any normal environmental sensing application imaginable. As always with an exposed cavity, care must be taken during the assembly process because the polymer can be damaged by chemical or assembly cleaning and the scrubbing process.