Vernier GDX-O2 User's Guide
®
Go Direct
O2Gas
(Order Code GDX-O2)
Go Direct O2Gas measures gaseous oxygen concentration and air temperature.
This sensor has a wide measurement range, which is ideal for studying human
and cellular respiration. A 250 mL Nalgene bottle is included for running
controlled experiments with small plants and animals.
Go Direct O2Gas can be used in a variety of experiments:
l Test catalase activity under various conditions.
l Measure oxygen consumption at rest and after exercise.
l Measure the change in O
l Compare the rates of cell respiration in germinating and non-germinating
peas.
Note: Vernier products are designed for educational use. Our products are not
designed nor are they recommended for any industrial, medical, or commercial
process such as life support, patient diagnosis, control of a manufacturing
process, or industrial testing of any kind.
What's Included
l Go Direct O
l Micro USBCable
l 250 mL Nalgene Bottle w/Lid
2
Gas
Compatible Software
See www.vernier.com/manuals/gdx-o2 for a list of software compatible with
GoDirectO2Gas.
Getting Started
Please see the following link for platform-specific connection information:
Bluetooth Connection USB Connection
1. Install Vernier Graphical
Analysis™ on your computer,
Chromebook™, or mobile device. If
using LabQuest®, make sure
LabQuest App is up to date. See
www.vernier.com/ga4 for Graphical
Analysis availability or
www.vernier.com/downloads to
update LabQuest App.
2. Charge your sensor for at least
2hours before first use.
gas produced during photosynthesis.
2
www.vernier.com/start/gdx- o2
1. If using a computer or
Chromebook, install Vernier
Graphical Analysis. If using
LabQuest, make sure LabQuest
App is up to date. See
www.vernier.com/ga4 for Graphical
Analysis availability or
www.vernier.com/downloads to
update LabQuest App.
2. Connect the sensor to the USB
port.
3. Turn on your sensor by pressing the
power button once. The LED will
blink red.
4. Launch Graphical Analysis or turn
on LabQuest.
5. If using Graphical Analysis, click
3. Launch Graphical Analysis or turn
on LabQuest. You are now ready to
collect data.
4. This is a multi-channel sensor. To
change the channel selections, see
www.vernier.com/start/gdx-o2
or tap Sensor Data Collection. If
using LabQuest, choose Wireless
Device Setup > Go Direct from the
Sensors menu.
6. Select your Go Direct sensor from
Note: This sensor does not work with
the original LabQuest. It works with
LabQuest 2 or LabQuest 3.
the list of Discovered Wireless
Devices. Your sensor's ID is located
near the barcode on the sensor. The
LED will blink green when it is
successfully connected.
7. Click or tap Done. You are now
ready to collect data.
8. This is a multi-channel sensor. To
change the channel selections, see
www.vernier.com/start/gdx-o2
Charging the Sensor
Connect Go Direct O2Gas to the included Micro USB Cable and any USB
device for two hours.
You can also charge up to eight Go Direct O2Gas Sensors using our Go Direct
Charge Station, sold separately (order code: GDX-CRG). An LED on each
GoDirectO2Gas 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.
Powering the Sensor
Turning on the sensor
Putting the sensor in sleep
mode
Press button once. Red LED indicator flashes
when unit is on.
Press and hold button for more than three
seconds to put into sleep mode. Red LED
indicator stops flashing when sleeping.
Connecting the Sensor
See the following link for up-to-date connection information:
1
www.vernier.com/start/gdx- o2
Connected and charging Blue and Green LED solid when sensor is con-
nected 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.
Identifying the Sensor
When two or more sensors are connected, the sensors can be identified by
tapping or clicking Identify in Sensor Information.
Using the Product
Connect the sensor following the steps in the Getting Started section of the user
manual.
Note: For best results, keep the sensor upright as much as possible during use.
Reading may drift if used in a horizontal position.
Channels
Go Direct O2Gas has three measurement channels:
l O
Gas
2
l O
Gas - rTC
2
l Temperature
O2Gas
This channel measures the oxygen concentration in the air. Units can be
changed from percent (%) to parts per thousand (ppt), parts per million (ppm), or
or mg/m3. See www.vernier.com/til/3846 for more information. There is built-in
temperature compensation on this channel that is most effective for slow
temperature changes. For rapid temperature changes, consider using the O2GasrTCchannel. O2Gas is the default channel that is active when the sensor is
connected.
O2Gas - rTC
This channel measures oxygen gas concentration, but in addition to the built-in
temperature compensation, it uses the on-board thermistor to apply a rapid
temperature correction to the oxygen gas reading. This channel should only be
used in experiments where starting conditions will be at room temperature and
where rapid changes in temperature are likely to occur. Units can be changed
from percent (%) to parts per thousand (ppt), parts per million (ppm), or mg/m3.
See www.vernier.com/til/3846 for more information. This channel is not active by
default when then the sensor is connected.
Temperature
This channel measures air temperature and is used for rapid temperature
compensation. Units can be changed from °C to °F or K. This channel is not
active by default when the sensor is connected.
Videos
View videos related to this product at www.vernier.com/gdx-o2
Calibrating the Sensor
O2Gas
The sensor is factory calibrated. For many experiments, it will not be necessary
to calibrate. However, for best accuracy, 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 this user manual. Once finished, the sensor should read
20.9% (or the value entered in the table).
O2Gas - rTC
The channel is factory calibrated. For many experiments, it will not be necessary
to calibrate the sensor when using this channel. However, for more accurate
measurements, the channel can be calibrated using the instructions in the
O2Gas section of this user manual.
Temperature
The temperature sensor is factory calibrated and cannot be calibrated by the
user.
Effect of Humidity
Because the oxygen concentration varies with the amount of water vapor in the
atmosphere, you may want to adjust your atmospheric oxygen calibration value
to improve accuracy when using the sensor. The accepted value of 20.9% for
atmospheric oxygen levels is calculated in dry air (0% relative humidity). If you
know the relative humidity of the location at which you are calibrating, you can
substitute one of the values in the table below in place of 20.9%. You can also
use the formula below to calculate the corrected oxygen level for calibration.
Oxygen concentration decreases linearly as humidity increases. The formula that
describes this relationship is
y = –0.008x + 20.9, where y = corrected oxygen concentration and x =
measured relative humidity.
Relative humidity (%) 0 25 50 75 100
Oxygen (%) 20.9 20.7 20.5 20.3 20.1
2
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