Humidity SensorHumidity Sensor

Presented by:Presented by:

Key Kai WongKey Kai Wong

OutlineOutline

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

What is Relative Humidity (RH)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 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

.

Manufacturers of Humidity Sensor Manufacturers of Humidity Sensor

Honeywell ( HIH series )

Sensirion ( SHT Series )

Humidity Sensor from HoneywellHumidity Sensor from Honeywell ( HIH series) ( 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

HIH-3610 Series

Humidity Sensor from SensirionHumidity Sensor from Sensirion( SHT Series )( 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

Series interfaceSeries interface

Comparision..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.

ConclusionConclusion

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.

ReferencesReferences

• 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