• Go Direct CO₂ Gas
• Micro USB Cable
• 250 mL Nalgene Bottle w/Lid

Choose a platform below to see its compatibility requirements.

LabQuest

Interface	LabQuest App
LabQuest 3	Full support
LabQuest 2 (discontinued)	Full support 1
LabQuest (discontinued)	Incompatible

Compatibility Notes

1. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

Computers

	Software
Interface	Graphical Analysis
No interface required	Full support 1
LabQuest 3	Full support 2
LabQuest 2 (discontinued)	Full support 2 3

Compatibility Notes

1. For Bluetooth^® connectivity, only computers running Windows 10 or Mac OS X 10.10 or newer are supported. The computer must also have a compatible Bluetooth 4.0⁺ radio.
2. Connect this sensor directly to a computer or Chromebook via a USB or wireless Bluetooth^® connection for best results. Alternatively, this sensor is fully supported when used with LabQuest 2 or LabQuest 3 when the LabQuest is connected to a computer or Chromebook via Wireless Data Sharing.
3. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

Chromebook

	Software
Interface	Graphical Analysis
No interface required	Full support
LabQuest 3	Full support 1
LabQuest 2 (discontinued)	Full support 1 2

Compatibility Notes

1. Connect this sensor directly to a computer or Chromebook via a USB or wireless Bluetooth^® connection for best results. Alternatively, this sensor is fully supported when used with LabQuest 2 or LabQuest 3 when the LabQuest is connected to a computer or Chromebook via Wireless Data Sharing.
2. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

iOS

	Software
Interface	Graphical Analysis	Graphical Analysis GW
No interface required	Full support	Full support
LabQuest 3	Full support 1 2	Full support 1 2
LabQuest 2 (discontinued)	Full support 1 2 3	Full support 1 2 3

Compatibility Notes

1. Connect this sensor directly to a supported mobile device via a wireless Bluetooth^® connection for best results.
2. iOS and Android^™ devices can only connect to LabQuest 2 or LabQuest 3 via Wireless Data Sharing.
3. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

Android

	Software
Interface	Graphical Analysis	Graphical Analysis GW
No interface required	Full support	Incompatible
LabQuest 3	Full support 1 2	Full support 1
LabQuest 2 (discontinued)	Full support 1 2 3	Full support 1 3

Compatibility Notes

1. iOS and Android^™ devices can only connect to LabQuest 2 or LabQuest 3 via Wireless Data Sharing.
2. Connect this sensor directly to a supported mobile device via a wireless Bluetooth^® connection for best results.
3. Wireless connection of this sensor to a LabQuest 2 requires a Go Direct Bluetooth Adapter when used with some older LabQuest 2 models.

Python

	Software
Interface	Python
No interface required	Full support

Javascript

	Software
Interface	Javascript
No interface required	Full support 1

Compatibility Notes

1. A wireless Bluetooth^® connection can be made with Go Direct sensors on any platform running a browser with WebBluetooth support. However, only a few operating systems have been tested and testing has been limited.

LabVIEW

	Software
Interface	NI LabVIEW
No interface required	Full support 1

Compatibility Notes

1. For Bluetooth^® connectivity, only computers running Windows 10 or Mac OS X 10.10 or newer are supported. The computer must also have a compatible Bluetooth 4.0⁺ radio.

1. Charge your sensor for at least 2 hours before first use.
2. Turn on your sensor. The LED will blink red.
3. Launch Graphical Analysis, then click Sensor Data Collection.
4. Select your sensor from the list. The sensor ID is located on the sensor label near the bar code. Note: If you don’t see a list of available sensors, click WIRELESS. After selecting your sensor, click Pair.
5. This is a multi-channel sensor. Click SENSOR CHANNELS and select the channel(s) you want to use.
6. Click DONE. You are now ready to collect data.

Using other Vernier data-collection apps or want to connect via USB?

Visit www.vernier.com/start-go-direct

Note: This sensor also works with LabQuest 2 and LabQuest 3; it does not work with the original LabQuest.

Connect Go Direct CO₂ Gas to the included Micro USB Cable and any USB device for two hours.

You can also charge up to eight Go Direct CO₂ Gas Sensors using our Go Direct Charge Station, sold separately (order code: GDX-CRG). An LED on each Go Direct CO₂ Gas indicates charging status.

Charging	Blue LED on steady while sensor is connected to the Micro USB Cable or Charge Station.
Fully charged	Blue LED is off when charging is complete.

Turning on the sensor	Press button once. Red LED indicator flashes when unit is on.
Putting the sensor in sleep mode	Press and hold button for more than three seconds to put into sleep mode. Red LED indicator stops flashing when sleeping.

See the following link for up-to-date connection information:

www.vernier.com/start/gdx-co2

Connected and charging	Blue and Green LED solid when sensor is connected to Graphical Analysis via USB and unit is charging. (Green LED is obscured by the blue one.)
Connected, fully charged	Green LED solid when sensor is connected to Graphical Analysis via USB and the unit is fully charged.
Charging via USB, connected via Bluetooth	Blue LED is solid and green LED is flashing, but the green flashing LED looks white because it is overwhelmed by the blue.

When two or more sensors are connected, the sensors can be identified by tapping or clicking Identify in Sensor Information.

Connect the sensor following the steps in the Getting Started section of this user manual.

Channels

Go Direct CO₂ Gas has three measurement channels:

• CO₂ Gas
• Temperature
• Relative Humidity

CO₂ Gas

This channel measures the carbon dioxide concentration in the air. Units can be changed from parts per million (ppm) to parts per thousand (ppt), percent (%), or mg/m³. See www.vernier.com/til/3845 for more information. The readings are temperature compensated regardless of whether the temperature channel is activated. This is the default channel that is active when the sensor is connected.

Temperature

This channel measures air temperature inside the sensor. Units can be changed from °C to °F or K. This channel is not active by default when the sensor is connected.

Relative Humidity

This channel measures the relative humidity of the air. It is not used to compensate CO₂ gas readings. This channel is not active by default when the sensor is connected.

CO₂ Gas

The CO₂ Gas sensor is factory calibrated. For many experiments, it will not be necessary to calibrate this sensor when using this channel. However, for best accuracy, the sensor can be calibrated using a one-point calibration based on a sample of outside air. Atmospheric air typically has a carbon dioxide concentration of around 400 ppm. Actual levels in your area may be slightly higher due to localized influences such as automobile or industrial emissions of carbon dioxide. To calibrate Go Direct CO₂ Gas

1. Fill the 250 mL Nalgene bottle to the brim with water, take it outside, and dump the water to ensure it is then filled with fresh air. While still outdoors, insert the sensor into the gas sampling bottle that now contains fresh outside air. Take the bottle and sensor to where the calibration will be done.
2. Start the software and identify your sensor, if necessary. Let the sensor warm up for at least 180 seconds before continuing.
3. When the sensor has warmed up (readings should have stabilized), calibrate the sensor using a one-point calibration. Enter a value of 400 ppm for the sample of air collected. Once finished, the sensor should read very close to 400 ppm.

Temperature

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

Humidity

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

CO2 Sensor
Type	NDIR
Range	0–100,000 ppm
Accuracy	0 to 1,000 ppm ±100 ppm 1,000 to 10,000 ppm ±5% of reading +100 ppm 10,000 to 50,000 ppm ±10% of reading 50,000 to 100,000 ppm ±15% of reading
Resolution	1 ppm CO2
Warm-up time	180 seconds
Gas sampling mode	diffusion
Temperature Sensor
Type	IC
Accuracy	±1°C
Resolution	0.1°C
Relative Humidity Sensor
Type	IC
Range	0 to 100% (non-condensing)
Accuracy	±5% or better
Resolution	0.1%
USB specification	2.0
Wireless specification	Bluetooth 4.2
Maximum wireless range	30 m unobstructed
Battery	650 mA Li-Poly
Battery life (single full charge)	~8 hours
Battery life (long term)	~500 full charge cycles (several years depending on usage)
Normal operating temperature range	20 to 40°C
Operating humidity range	5 to 95% (non-condensing)
Dimensions	Sensor tube: 82 mm length, 28 mm OD; total length: 200 mm

Battery Information

Go Direct CO₂ Gas contains a small lithium-ion battery. The system is designed to consume very little power and not put heavy demands on the battery. Although the battery is warranted for one year, the expected battery life should be several years. Replacement batteries are available from Vernier (order code: GDX-BAT-650).

Storage and Maintenance

To store Go Direct CO₂ Gas for extended periods of time, put the device in sleep mode by holding the button down for at least three seconds. The red LED will stop flashing to show that the unit is in sleep mode. Over several months, the battery will discharge but will not be damaged. After such storage, charge the device for a few hours, and the unit will be ready to use.

Exposing the sensor to temperatures below –15°C or over 45°C will damage the sensor. Additionally, temperatures over 35°C (95°F) will reduce the battery's lifespan. If possible, store the device in an area that is not exposed to temperature extremes.

Note: It is recommended that you wash the Nalgene bottle by hand. Most dishwashers will melt plastic bottles.

Water Resistance

Important: Go Direct CO₂ Gas is neither waterproof, nor is it water resistant, and should never be immersed in water.

If any liquid gets into the device, immediately power the unit down (press and hold the power button for more than three seconds). Disconnect the sensor and charging cable, and remove the battery. Allow the device to dry thoroughly before attempting to use the device again. Do not attempt to dry using an external heat source.

Note: Damage due to liquid is not covered under warranty.

Go Direct CO₂ Gas measures gaseous carbon dioxide levels in the range of 0 to 100,000 ppm by monitoring the amount of infrared radiation absorbed by carbon dioxide molecules. Carbon dioxide gas moves in and out of the sensor tube by diffusion through the vent holes in the sensor tube. The sensor uses a small light to generate infrared radiation (IR). The IR source is located at one end of the sensor’s shaft. At the other end of the shaft is an infrared sensor that measures how much radiation gets through the sample without being absorbed by the carbon dioxide molecules. The detector measures infrared radiation in the narrow band centered at 4260 nm. The greater the concentration of the CO₂ gas in the sampling tube, the less radiation will make it from the source through the sensor tube to the IR detector.

The sensor also measures air temperature in the sensor shaft using a thermistor in an integrated circuit. When the temperature increases, the resistance of the thermistor decreases. The circuit measures the resistance value at a particular temperature and converts this to a digital signal.

Relative humidity is measured in the sensor shaft using an integrated circuit that uses a capacitive polymer to sense humidity. The circuit produces a signal which varies with relative humidity.

• Very important: Do not place the sensor into any liquid. The sensor is intended only for measuring gaseous, not aqueous, CO₂ concentration.
• Allow the sensor to warm up for at least 180 seconds before use. The warm-up process begins when the sensor is charging, connected to a USB port, or connected to software via Bluetooth wireless technology.
• The sensor is sensitive to high humidity. Do not use in a condensing environment.
• The sensor has built-in temperature compensation but the sensor can still be sensitive to rapid and/or large changes in temperature. The sensor is designed to operate best between 20 and 40°C. This does not prohibit the sensor from being used in temperatures outside this range. Just allow enough time for the sensor to stabilize at the desired air temperature. For more accurate results, the sensor can be calibrated at the temperature used.
• The recommended sampling rate is 0.5 samples per second or slower for this sensor. This allows the sensor to average a set of measurements before reporting a value. Gas must diffuse through the holes in the sensor tube before the sensor detects any changes in concentration. Because diffusion of gases is a slow process, there can be a delay in response time.
• To collect data in a controlled environment, it is recommended that you use the 250 mL Nalgene bottle that is included with this sensor.
• To collect data simultaneously with Go Direct CO₂ Gas and Go Direct O₂ Gas, it is recommended that you purchase either the BioChamber 250 (250 mL capacity) or the BioChamber 2000 (2 L capacity). Each BioChamber has a second opening with a grommet so that you can insert two probes at once.
• Because the sensor operates on the basis of reading IR radiation, you should avoid using the sensor in direct sunlight as much as possible. Even though the IR detector is shielded, it is best to avoid the possibility of reflected light affecting the readings by keeping the sensor in the shade when used outdoors.
• If the reported CO₂ gas concentration appears to be incorrect (after the 180 second warm up), calibrate the sensor as described in the Calibration section. Keep in mind that indoor CO₂ gas concentration can vary a great deal and that there can be unit to unit variability of up to 200 ppm CO₂ between sensors.
• If the sensor is reading at or near the maximum range of the sensor, the CO₂ concentration may be exceeding the maximum range of the sensor. Place the sensor in outside air or in ambient room air and wait for the readings to decrease.
• If there is no change in CO₂ gas concentration during an experiment, it may be the experiment and not the sensor. Test the sensor by removing it from the reaction chamber and gently blowing on the shaft to see if it responds to exhaled air.

For more troubleshooting and FAQs, see www.vernier.com/til/4128

If you have followed the troubleshooting steps and are still having trouble with your Go Direct CO₂ Gas, contact Vernier Technical Support at support@vernier.com or call 888-837-6437. Support specialists will work with you to determine if the unit needs to be sent in for repair. At that time, a Return Merchandise Authorization (RMA) number will be issued and instructions will be communicated on how to return the unit for repair.

Item	Order Code
BioChamber 250	BC-250
BioChamber 2000	BC-2000
250 mL Nalgene Bottle w/Lid	CO2-BTL
Micro USB Cable	CB-USB-MICRO
USB-C to Micro USB Cable	CB-USB-C-MICRO
Go Direct 650 mAh Replacement Battery	GDX-BAT-650

Warranty information for this product can be found on the Support tab at www.vernier.com/gdx-co2/#support

General warranty information can be found at www.vernier.com/warranty