Go Direct^® O₂ Gas Sensor (GDX-O2)

• Specifications and User Guide
• Which Oxygen Gas Sensor do I have?

Note: This information is for the Go Direct O₂ Gas Sensor. For information about O₂ Gas Sensor (O2-BTA) see O₂ Gas Sensor Troubleshooting and FAQs.

Troubleshooting

General: Press the power button on the sensor to turn it on. Connect your sensor as described in the Getting Started instructions for your device. (The green LED will flash to indicate the sensor is connected.)

• Primary Test: Blow on the sensor. Do you see a decrease in the Oxygen Gas reading? This tells you that the sensor is responding.

Tips

Here are some things to consider

1. Has the sensor been stored upright? The O2 Gas Sensor must be stored upright when not being used. This is necessary to maintain the sensor. Failure to store upright will reduce the life of the sensor.
2. Is your data-collection period too short? Diffusion of gases is a fairly slow process; there can be some delay in readings.
3. Are you collecting data in a controlled environment? To collect data in a controlled environment, use the 250 mL Nalgene collection bottle that is included with the sensor.

Please see extended troubleshooting tips in the Specifications and User Guide.

Additional Troubleshooting

• How do I calibrate the Go Direct O2 Gas?
• Can my Go Direct O2 Gas Sensor be repaired?
• Do any of your sensors require special storage?
• Can I use a dishwasher to wash the Nalgene bottle that shipped with my O2 or CO2 Gas Sensor?
• How can I insert a CO2 Gas Sensor or O2 Gas Sensor into my own container?
• Can O₂ gas concentration be expressed in units of mg/m³?
• What is the volume of gas displaced by the shaft of the CO₂ and O₂ Gas Sensor? What is the total volume of the Large and Small BioChambers?

Specifications

O2 Gas Sensor Specifications

• Type: Electrochemical cell
• Range: 0-100% (0-1000 ppt) O2
• Accuracy: (at standard pressure 760 mm Hg) ±1% volume O2
• Typical resolution: 0.01% O2
• Response time: ~12 seconds to 90% of final value
• Warm-up time: Less than 5 seconds to 90% of final value
• Pressure effect: Directly proportional
• Pressure range: 0.5 atm to 1.5 atm
• Gas sampling mode: Diffusion
• Normal operating temperature range: 10 to 40°C
• Operating humidity range: 0 to 95% RH

Temperature Sensor Specifications

• Type: Thermistor
• Range: -25 to 125°C
• Accuracy: ±0.5°C
• Resolution: 0.1°C
• Response time: Less than 5 seconds to 90% of final value
• Storage temperature range: -5 to +50°C
• Dimensions: Sensor tube: 38 mm length, 28 mm OD; total length: 155 mm
• Connections:
  ⚬ Wireless: Bluetooth^® v4.2 (wireless range 30 m unobstructed)
  ⚬ Wired: USB 2.0 full speed
• Battery: 650 mA Li-Poly
  ⚬ Battery Life (single, full charge): ~24 hours continuous data collection
  ⚬ Battery Life (lifetime): 2 – 5 years (typical)

Calibration

O₂ GAS

The sensor is factory calibrated. For many experiments, it will not be necessary to calibrate. However, for more accurate measurements, the sensor can be calibrated using a one-point calibration using a known concentration of atmospheric oxygen. Enter a value of 20.9% oxygen or a corrected value from the table in the Effect of Humidity section of the user manual for air. Once finished, the sensor should read 20.9% (or the value entered in the table).

O₂ GAS – w TC

This sensor channel does not allow calibration since it provides temperature compensated readings based on the O₂ and Temperature sensors. To calibrate the O₂ sensor channel, see the instructions above.

TEMPERATURE

The sensor is factory calibrated and cannot be calibrated by the user.

Battery Troubleshooting

1. If the sensor can be turned on when connected by USB but not when disconnected from USB, the battery either needs charging or has reached its end of life and can no longer hold a charge.
   ⚬ Try charging the sensor for several hours.
2. If the sensor still won’t turn on when disconnected from USB, try swapping the battery with a working sensor to see if the problem follows the battery or stays with the sensor.
   ⚬ If the problem stays with the sensor, the battery is probably not the issue.
   ⚬ If the problem follows the battery, the battery has likely reached its end of life.
3. If you intend to use this sensor wirelessly, its battery will need replacing. Go Direct® 650 mAh Replacement Battery (GDX-BAT-650)
4. See How do I replace the battery in a Go Direct Wand-Type Sensor? for more information (including a video).

Rechargeable batteries are covered by a one-year warranty.
Batteries should last two to five years in typical use.