Transcript Humidity Sensor

Humidity Sensor
Presented by:
Key Kai Wong
Outline
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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)
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 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 Sensirion
( SHT Series )
• 2 sensors for relative humidity & temperature
• Very easy-to-use due to calibration & digital 2wire 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 interface
Comparision..
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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.
Sensirion
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( 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
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