In most cases it is not necessary to calibrate sensors; however, for optimum accuracy you may choose to perform a calibration.

To perform any calibration, you will need one or more external references for your sensor. For example, to do a two-point calibration for a pH sensor you will need two pH buffer solutions. Your calibration is only as good as your knowledge of the reference values. Note: For best results, the two calibration points should be widely separated and on either side of the readings you anticipate in your experiment.

A two-point calibration is always better than a one-point calibration, but sometimes it is more convenient to adjust the sensor reading to a single reference. A one-point calibration assumes that the slope for a sensor’s calibration is good and that only the intercept needs to be adjusted (these are all linear calibrations: y = mx + b). Some sensors (e.g., Go! Temp) will default to single-point calibration. Others will have single-point calibration available as an option in the calibration dialog.

Performing a Two-Point Calibration

1. Connect the sensor following the steps in the Getting Started section of the user manual or by going to www.vernier.com/start and selecting your sensor.
2. Start Logger Pro. The program will identify the sensor and load a default data-collection setup.
3. Choose Calibrate from the Experiment menu and then click the Calibrate Now button.
4. Place the sensor in the first known set of conditions (e.g., known suspended mass or known pH buffer). If using a wet sensor, remove the storage bottle from the sensor (if applicable), rinse the tip of the sensor with distilled water, and place the sensor in the first standard solution so the tip is immersed.
5. Type in the first known calibration value in the edit box. In the calibration dialog box, you will see the potential output of the sensor in volts. When the displayed voltage reading stabilizes, click Keep.
6. Move the sensor to the second set of known conditions. If using a wet sensor, rinse the sensor with distilled water and place it in the second standard solution. The potential (voltage) will change.
7. Enter the second known calibration value in the edit box. When the voltage reading stabilizes, click Keep.
8. (Optional) If you wish to store the calibration on the sensor itself, go to the Calibration Storage tab. Once stored, this new calibration will be used automatically, regardless of the interface to which the sensor is connected. If you wish to use the calibration only for the current experiment, proceed to Step 11.
9. Click Set Sensor Calibration. Make sure the Default Page corresponds to your new calibration. Click Set.
10. Click Done. You will be prompted by the message, “Warning: You are about to change information in your sensor. Configuration data stored on the sensor will be lost. Pressing ‘Write’ will apply your changes to the sensor.” Click Write.
11. Click Done to complete the calibration process.

Performing a One-Point Calibration

1. Connect the sensor following the steps in the Getting Started section of the user manual or by going to www.vernier.com/start and selecting your sensor.
2. Start Logger Pro. The program will identify the sensor and load a default data-collection setup.
3. Choose Calibrate from the Experiment menu and check the One Point Calibration box if it is not already checked.
4. Click the Calibrate Now button.
5. Place the sensor in a known environment (e.g., atmospheric pressure if calibrating a pressure sensor).
6. Type the known value in the edit box. In the calibration dialog box, you will see the potential output of the sensor in volts. When the displayed voltage reading stabilizes, click Keep.
7. (Optional) If you wish to store the calibration on the sensor itself, go to the Calibration Storage tab. Once stored, this new calibration will be used automatically, regardless of the interface to which the sensor is connected. If you wish to use the calibration only for the current experiment, proceed to Step 10.
8. Click Set Sensor Calibration. Make sure the Default Page corresponds to your new calibration. Click Set.
9. Click Done. You will be prompted by the message, “Warning: You are about to change information in your sensor. Configuration data stored on the sensor will be lost. Pressing ‘Write’ will apply your changes to the sensor.” Click Write.
10. Click Done to complete the calibration process.

You can reset the sensor to its factory calibration by following these steps. Note, however, that the factory calibration may no longer be a useful calibration if the sensor is not new.

1. Select Calibrate from the Experiment menu.
2. Click the Calibration Storage tab.
3. Click Set Sensor Factory Defaults.

RELATED TIL ENTRIES
Calibration in Other Data-Collection Programs:
How do I manually calibrate my sensor in Graphical Analysis and Graphical Analysis Pro?
How do I manually calibrate my sensor in LabQuest App?
How do I manually calibrate my Go Wireless pH or EA in Graphical Analysis GW for iPad or Android?
How do I store the calibration for my sensor using Logger Pro?

Specific Sensor Calibration Questions:
How do you calibrate an accelerometer?
Is there a way to calibrate a Motion Detector?
How do I save a custom calibration to my pH sensor?
I am using a third-party electrode with your Electrode Amplifier. How do I calibrate the electrode in Logger Pro 3?
Why does my pH sensor experience drift or calibration issues?
Can you calibrate a Stainless Steel Temperature Probe?
How do you calibrate a Go!Temp?
How do I calibrate a COL-DIN Colorimeter using the LabQuest App?
How do I calibrate my older Colorimeter?
Can I perform a two-point calibration for the Optical DO Probe?
Can I perform a custom calibration of a Vernier spirometer?
Do I need to calibrate the Goniometer?
Do I need to calibrate Vernier ethanol sensors?
Can I calibrate my PAR Sensor using the clear sky calculator