More Sensor Research

Base system:

• Dust sensor
• Gas sensor (VOC?)
• Relative humidity sensor

Notes on humidity

• Output of the sensors depends on humidity
• When humid, dust sensors detect water as small particles
• Gas sensors are also coupled to humidity
• Sensors not water proof (need rain-proofing)

Dust sensors on DigiKey

1. GP2Y1010AU0F Datasheet
2. GP2Y1023AU0F Datasheet
3. DN7C3CA006 Datasheet
4. SM-PWM-01A Datasheet

Notes on DigiKey sensors

• Sensors 1-3 output PWM/Analog, approximately proportional to dust density and have a lower operating current
• Sensor 4 has two outputs, one for PM2.5 and one for PM10.
  Output is a waveform (page 10 of the datasheet) that shows whenever the sensor has been obstructed by a particle.
  This sensor has a longer acquisition time because it uses a moving average to smooth out the data
• Need to find a way to calibrate the sensors

Gas sensors

• VOC sensor
• MQ-135
• These sensors have an internal heating element that needs to be preheated to a certain temperature in order to operate properly.
  
  • MQ-135 preheat time is approximately 24 hours
  • VOC sensor preheat time not listed, but the target temperature is 320 C
• Gas sensors do not measure precise concentrations
• Should investigate EPA standards on hazardous gases
• May need to contact Civil and Environmental Engineering department for calibration help