Humidity Sensors

Sparkfun: Humidity and Temperature Sensor - SHT15 Breakout

• Digital 2-wire interface
• Precise dewpoint calculation possible
• Accuracy +/- 1.5% 
• Measurement range: 0-100% RH
• Absolute RH accuracy: +/- 2% RH (10...90% RH)
• Repeatability RH: +/- 0.1% RH
• Temp. accuracy: +/- 0.3°C @ 25°C
• Fast response time < 4 sec.
• Low power consumption (typ. 30 µW)
• $41.95
• Datasheet

SparkFun: Humidity Sensor - HIH-4030 Breakout

• Near linear, analog output
• 4-5.8VDC voltage supply
• All pins broken out to a 0.1" pitch header
• Laser trimmed interchangeability
• Accuracy +/- 3.5% 
• Low power design, typical current draw of only 200μA
• Enhanced accuracy
• Fast response time
• Stable, low drift performance
•  $16.95
• Datasheet

Liquidware: Humidity and Temperature Sensor SHT21

• Bidirectional communication over a single pin on I2C protocol
• Energy consumption: 80 uW (at 12 bit, 3V, 1 measurement/s)
• Relative Humidity operating range: 0-100% RH
• Relative Humidity resolution of 0.03%
• Relative Humidity Response Time of 8 sec (tau 63%)
• Accuracy +/- 1.5%
• Temperature operating range: -40 to +125°C
• Temperature resolution of 0.01 C
• 4 pins: +5V, GND, Clock (SCL), Data (SDA)
• Board is 5V tolerant, allowing sensor to run from a 5V supply on Arduino I/O pins
•  $39.93
• Datasheet

Adafruit: Sensiron Temperature/Humidity Sensor - SHT11

• Communication: Two-Wire Serial
• Provides a fully calibrated, digital output
• Measure temperature with a resolution of 0.01 degrees and within +/- 2 degree accuracy
• Measures relative humidity with a resolution of 0.03%and within +/- 3.5% accuracy
• Low power consumption (typically 30 μW)
• Power requirements: 2.4 to 5.5 VDC
• Dimensions: 0.43 x 0.49 in (11 x 12.5 mm)
• Operating temp range: -40 to +254.9 �F (-40 to +123.8 �C)
• $35
• Datasheet

Seeed Studio Electronic brick - Indoor Temp & Humidity sensor

• Accuracy +/- 5%
• $9.50
• Datasheet