Humidity Sensor Presented by Key Kai Wong Outline

Humidity Sensor Presented by: Key Kai Wong

Outline • • What is Relative Humidity Manufacturers of Humidity Sensor from Honeywell ( HIH series) Humidity Sensor from Sensirion ( SHT Series) Comparision. . Conclusion Reference

What is Relative Humidity (RH) Measurement - Relative humidity (RH) is the amount of water vapor in the air compared with the amount of vapor needed to make the air saturated at the air's current temperature Example: At 3 p. m. the air has 9 grams of water vapor per cubic meter of air. We divide 9 by 30 and multiply by 100 to get a relative humidity of 30%

Water vapor air can hold in degrees C 30 degrees 20 degrees 10 degrees. 30 grams per cubic meter of air 17 grams per cubic meter of air 9 grams per cubic meter of air

Manufacturers of Humidity Sensor Honeywell Sensirion ( HIH series ) ( SHT Series )

Humidity Sensor from Honeywell ( HIH series) • Packages are chemically resistant • operate in ranges of -40 °C to 85 °C ( 40 °F to 185 °F) • Response time -15 sec in slowly moving air at 25 °C • Low power design – 200 micro. A @ 5 Vdc • Operating volatge 4 – 5. 8 v • On-chip signal processing ensures linear voltage output versus %RH. • $35 - $40 per unit price

HIH-3610 Series

Humidity Sensor from Sensirion ( SHT Series ) • 2 sensors for relative humidity & temperature • Very easy-to-use due to calibration & digital 2 wire interface • Calibrated & digital output (2 -wire interface) • Fast response time < 4 sec. • Temp. accuracy: +/- 0. 5°C @ 25 °C • Low power consumption (typ. 30 µW) • Operating Voltage 2. 8 - 5. 5 v • Cost $18 - $24 per unit price

Series interface

Comparision. . • • • Honeywell ( HIH series ) Response time -15 sec in slowly moving air at 25 °C Low power design – 200 micro. A @ 5 Vdc Operating volatge 4 – 5. 8 v $35 - $40 per unit price On-chip signal processing ensures linear voltage output versus %RH. Sensirion • • ( SHT Series ) Fast response time < 4 sec. Low power consumption (typ. 30 µW) Operating Voltage 2. 8 - 5. 5 v Cost $18 - $24 per unit price 2 sensors for relative humidity & temperature Very easy-to-use due to calibration & digital 2 -wire interface Calibrated & digital output (2 -wire interface) Temp. accuracy: +/- 0. 5°C @ 25 °C

Conclusion After considering the aspect of the operating voltage, cost, response time and the output of the sensor. Sensor SHT series is more suitable for our application.

References • Honeywell http: //content. honeywell. com/sensing/prodinfo/humiditymoisture/#applications • Sensirion http: //www. sensirion. com/en/sensors/humidity/default. htm • USToday http: //www. usatoday. com/weather/wrelhum. htm