Accurate humidity measurement despite exposure to volatile organic compounds

Volatile organic compounds (VOC) cause drift in capacitive humidity sensors, requiring a removal and reconditioning[FR1]  of the sensor. The HYT 223 is IST AG’s newest member of the HYT product series and allows for an automatic reconditioning directly in the application.

digital humidity and temperature module with an integrated micro-heater

When measuring humidity in environments with exposure to VOC, a drift occurs which causes faulty measurement results over time. A heating procedure is effective in restoring performance corresponding to calibrated output. However, removing the sensor from the application for reconditioning,amounts to high maintenance costs. Innovative Sensor Technology IST AG has therefore developed a multi-functional digital humidity and temperature module with an integrated micro-heater. With an automated reconditioning routine, drift-free operation with excellent accuracy can be maintained long-term.

Standard calibration setting:   ± 1.8 % RH  0-90 % RH and ± 3.0 % RH at 90-100 % RH @ 0 to 50°C (custom options upon request)

The integration of a heating resistor structure directly on the humidity sensor chip is a unique feature of the HYT 223 module which allows to recondition the sensor effectively at ≥120°C in application. Therefore, the reconditioning routine can be quick and in addition it can be adapted according to operational conditions. A protective PTFE membrane filter directly on the RH/T module protects the sensor from particles and further improves long term stability, while facilitating a compact assembly. As all members of the HYT product family, the HYT 223 module can resist conditions with water condensation. Possible applications for HYT 223 range from industrial drying processes, over environmental monitoring to medical devices.

Additional specification:

Operating range:               0 % RH to 100 % RH; -20 °C to +120 °C       
Hysteresis:                       <1%RH
Long-term drift (humidity/temperature):            < 0.5 % RH/a / < 0.05 K/a
Digital output:                    I
2C protocol
Heater:                            Pt50, <720mW