1. Humidity Sensor Presented by: Key Kai Wong

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

3. 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%

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

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

6. 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 microA @ 5 Vdc Operating volatge 4 – 5.8 v On-chip signal processing ensures linear voltage output versus %RH. $35 - $40 per unit price

8. HIH-3610 Series

9. 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 - 5.5v Cost $18 - $24 per unit price

11. Series interface

13. Comparision.. Sensirion ( SHT Series ) Fast response time < 4 sec. Low power consumption (typ. 30 µW) Operating Voltage 2.8 - 5.5v 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 Honeywell ( HIH series ) Response time -15 sec in slowly moving air at 25 °C Low power design – 200 microA @ 5 Vdc Operating volatge 4 – 5.8 v $35 - $40 per unit price On-chip signal processing ensures linear voltage output versus %RH.

14. 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.

15. References Honeywell http://content.honeywell.com/sensing/prodinfo/humiditymoisture/#applications 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